Nutritional Requirements of Animals

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Chapter 41 Animal Nutrition

Mariya

& Julia

Nutritional Requirements of Animals

1.

The three nutritional needs that must be met are: chemical energy for the cellular work of the body, the
organic raw materials animals use for biosynthesis, and
essential nutrients (substances the animal can't
form itself).

2.

Undernourishment is due to a lack of calories, the body starts to break down its glycogen, fat and protein
to make up for the difference; on the other hand, overnourishment is due to excessive
calorie intake,
excess fat is stored. An animal is malnourished when it missing one or more essential nutrients (the four
essential nutrients are amino acids, fatty acids, vitamins and minerals).

3.

Fat hoarding may have provided a fitness advantage to our an
cestors because this would make them less
at a chance for malnourishment and raise their fitness because they were able to produce healthy
offspring.

4.

Essential nutrients are substances that animals cannot make for themselves from any raw materials and
has
to take it in its pre
-
made form. The four classes of essential nutrients are amino acids (animals
require 20 amino acids to make proteins), fatty acids (animals cannot make some unsaturated fatty
acids), vitamins (only needed in small amounts, only 13), an
d minerals (simple inorganic nutrients also
required in small amounts: Ca, Fe and P).

5.

Water soluble vitamins include B which works as coenzymes and C is used for connective tissue. Excess
water soluble vitamins are lost through urination. Fat soluble vitam
ins include A for vision, D for
calcium absorption, E, and K for blood clotting. Excess fat soluble vitamins are stored in body fat.

6.

The four main stages of food processing are ingestion, digestion, absorption, and elimination. Ingestion
is the actual eati
ng. Digestion is when food is broken down into small enough molecules for absorption
(digestion uses hydrolysis to break down the macromolecules). Absorption happens when the broken
down molecules are taken into cells. Elimination is when the undigested ma
terial leaves the body as
waste.

7.

Intracellular digestion occurs inside the cell such as food vacuoles in protists, which take in the food by
pinocytosis or phagocytosis, then the food vacuoles are helped by lysosomes (which provide the
digestive enzymes),
the animals that also do this are sponges. Extracellular digestion happens in most
animals, hydrolysis occurs, and this allows the animal to devour large prey that wouldn't have been
possible if animals just phagocytized.


8. Digestion breaks down
molecule
s small enough for the body to absorb.
It
consists of the alimentary canal and various
accessory glands

including the salivary glands, pancreas, liver, and
gallbladder that secrete digestive juic
es into the
canal through ducts
.

After chewing is completed
, food is swallowed and goes down the esophagus, which takes 5 to 10
seconds until it reaches the stomach, where it remains for 2 to 6 hours being partially digested. Then, final digestion and
nutrient absorption occurs in the small intestine for a period
of about 5 to 6 hours. After
12 to 24 hours
, any undigested
material

goes through the
large intestine and wastes exit the body through the anus.

9. Saliva contains mucin, which protects the soft lining of the mouth from abrasion and lubricates the food fo
r easier
swallowing. It also contains buffers that prevent tooth decay. Saliva also has antibacterial agents
that kill many bacteria
found in food. Salivary amylase is an enzyme in saliva that hydrolyzes starch and glycogen.

10.
Macromolecules are mostly

digested in the small intestine.
Digestion breaks down macromolecules into monomers
by the enzymatic process of hydrolysis so that the animal can make its own molecules or use it as fuel for ATP
production.

After digestion is completed, absorption occurs
in which the animal's cells take up the monomers formed by
digestion.

11. Pepsin does not digest the stomach lining because
the stomach has a line of defense, which is a coating of mucus
that protects the stomach lining from self digestion
.

12.
Most of
digestion and absorption of macromolecules occurs in the small intestine. The first part of the small
intestine is the duodenum, where acid chyme from the stomach mixes with digestive juices from the pancreas, liver, gall
bladder, and gland cells of the in
testinal wall. This is where most of digestion occurs. The epithelial lining of the
duodenum produces several enzymes used in digestion. The liver produces bile which contains bile salts that act as
detergents necessary in aiding in digestion and absorpti
on of fats. The other two regions of the small intestine are the
jejunum and ileum, both of which function in absorption of nutrients and water. The nutrients are mostly absorbed
across the large surface of the intestinal walls and the across the unicellul
ar epithelium of capillaries or lacteals.

13. One of the major functions of the large intestine is recovering water that has entered the alimentary canal as the
solvent to various digestive juices
. Also, numerous types of harmless bacteria live in the larg
e intestine. Most of these
bacteria, such as
Escherichia coli

generate gases, including methane and hydrogen sulfide

as a byproduct of their
metabolism.

Some bacteria produce vitamins,
which include

biotin, folic acid, vitamin
K, and B vitamins, that

add
on

to
our dietary intake of vitamins.

Feces (digestive wastes) move along the large intestine and contain many undigested
materials including cellulose, which helps move food along the digestive tract.

14.
Herbivores' dentition involves flat teeth, which
allow them to grind their food before swallowing it.
They have
bacteria in their intestines that produce enzymes that can break down cellulose
. Herbivores also have a long alimentary
canal relative to their body size, which pr
ovides more time for digestion

and a larger surface area for absorption of
nutrients in their diet. Carnivores' dentition involves extremely sharp pointed teeth for the purpose of grasping their
prey and tearing through its flesh, which is then swallowed whole. They have a much shorter

intestinal tract and a
relatively large and expandable stomach for holding large body parts of their prey. The omnivores posses aspects of the
dentition and digestive tract of both herbivores and carnivores. They have a variety of flat teeth (molars) and
sharp
teeth (
canines
). In addition th
ey also have a relatively long digestive tract relative to their body size. While they do eat
vegetable matter, they cannot eat particular grains and plants that can only be consumed by herbivores

because they
lack some

of the bacteria important for breaking down cellulose
.

15. Many vertebrates have large populations of symbiotic bacteria
and protists in special fermentation chambers in their
alimentary canals

in order to produce enzymes that hydrolyze cellulose into si
mple sugars that the vertebrate can then
digest and absorb.










Chapter 42 Respiration

Gas exchange in Animals

Julia

1.

Gas exchange is the uptake of O2 and the release of CO2. Gas is exchanged between respiratory
medium and body
fluids through diffusion across a respiratory surface.

2.

O2 diffuses across a respiratory surface
,

so surface area and distance is important. The structure of a
respiratory surface on the organism's rate of metabolism and the size of the actual organism. Som
e
respiratory organs include skin (earthworms); gills, trachae, and lungs which are more common for
bigger animals.

3.

The respiratory adaptations of aquatic animals are gills, foldings of the body surface that are suspended
in the water. Ventilation helps mo
ve H20 through the gills, which uses energy. Fish use concurrent
exchange to ensure a diffusion gradient.

4.

The disadvantages of water as a respiratory medium are that it holds a low concentration of air and has a
lower diffusion rate than air; the advantage

of water is that the simplest mode of respiration is through
diffusion.

5.

In countercurrent exchange, blood flows the opposite direction when H20 flows over the gills (in fish),
this maintains a constant concentration gradient for O2 between H20 and blood p
assing over the gills.
As an end result, this removes 80% of O2 dissolved in H20. Concurrent flow (blood and O2 move in the
same direction) results in a drop to <50% removal.

6.

Air has a higher concentration of O2 than H20 and its low density helps it diffus
e faster and makes it
easier to move through. Water is conserved by the folded respiratory tissue in the body. The
disadvantage of air as a medium is its complexity (it’s not as simple as it would be through a water
medium). Tracheal systems are used by in
sects and it is made up by tubes throughout their bodies. The
contraction of flight muscles helps move the air throughout the tracheal system (rapid diffusion, high 02
concentration).

7.

Mammals use negative pressure breathing to pull air into the lungs. The
diaphragm contracts and the
ribs rotate upward (increases volume of thoracic cavity and releases pressure the internal pressure) , the
lungs fill with air. Then, during exhalation, the rib muscles and the diaphragm muscles relax (reduces
volume). The lungs

are surrounded by a double
-
walled sac with a thin fluid filled space in between

(this
allows movement of the lu
ngs in the chest.

8.

Positive pressure breathing is exhibited in frogs; it is when an organism expands its mouth tissue
to push air down into its l
ungs. Negative pressure breathing occurs when a change in volume
occurs that draws air into the lungs. In humans, air is drawn in when the diaphragm contracts,
allowing the lungs to expand and increasing their volume. Air is exhaled when the diaphragm
rela
xes, lessening the volume of the lungs and forcing the air back out.

9.

Tidal volume is the total volume of air inhaled and exhaled with each breath. Vital capacity is the
maximum tidal volume during forced breathing. It is impossible to exhale all of the air

in the lungs,
since that would require totally collapsing the alveoli. Therefore, residual volume is the amount of
air left in the lungs even after as much air as possible is forcefully exhaled.

10.

While mammals rely only on lungs for their respiration, bir
ds have a more complicated system.
Birds have air sacs, in addition to thoracic lungs, throughout their bodies which contract to draw
air in, then expand to push it out. The whole system is connected in a linear fashion; air passes
through in one direction

regardless of inhalation or exhalation. Gas exchange is accomplished in
vascular bodies called parabronchi, which do not bottleneck off as alveoli do. So, a bird can
exchange the air in its lungs with every breath, making its maximum lung oxygen concentra
tion
higher than that of a mammal.

11.

Breathing in humans is controlled by two brain regions: the pons, and the medulla oblongata. The
breathing control center in the oblongata senses stretch
-
signal nerves that prevent the lungs from
overexpanding during inh
alation. The Medulla sets the pace for breathing in this way. The Medulla
also controls breathing by monitoring pH; when CO2 in the lungs becomes abundant, it reacts with
water to form carbonic acid. The Medulla detects this change in pH and causes breathi
ng to
deepen and quicken in order to expel excess CO2.

12.

Partial pressure is the pressure that a specific part of the atmosphere exerts. Gas diffuses down
from a region of higher partial pressure. The blood that travels to the lungs has a lower partial
press
ure for oxygen and a higher partial pressure for CO2 than the air in the alveoli. Therefore,
CO2 diffuses out of the blood and O2 diffuses in. Partial pressure also supplies O2 in the
capillaries, with CO2 diffusing into the interstitial fluid and O2 diffu
sing in from the fluid.

13.

Respiratory pigments are advantageous because they enable blood cells to carry acceptable and
realistic amounts of oxygen at a given time, reducing the need for excess cardiac pumping.
Hemocyanin is common to mollusks and arthropods
, is copper
-
based, and gives the blood a blue
hue. Hemoglobin is the most common oxygen
-
binding component in vertebrates, and is built with
4 heme subunits attached to an iron atom, which actually holds the O2. A hemoglobin molecule
can carry 4 O2 molecule
s, as a result of the 4 subunits. It colors blood red.

14.

The saturation of O2 in hemoglobin increases as the partial pressure increases, however the
saturation tops off at 100% and at that point can be used as O2 reserves for active
-
metabolizing
cells. Affin
ity for O2 drops as the % saturation of hemoglobin increases.


15.

Carbon Dioxide has three ways of getting from the cells back to the lungs: transport by
hemoglobin, going in solution with plasma, or being transported as bicarbonate ions. CO2 is
converted to

carbonic acid by carbonic anhydrase, and it dissociates into a hydrogen ion (which
attaches to hemoglobin) and bicarbonate ion, which diffuses into the plasma. The process is
regressed more quickly once the lungs are reached, with the bicarbonate reformin
g as CO2 and
diffusing out of the lungs.

16.

Air breathing diving animals, like whales and seals, adapted to store less oxygen in their lungs and
much more in their blood and muscle, which is enabled due to a high amount of the oxygen
-
storing protein myoglobin
. Additionally, during a dive, these organisms take measures to minimize
oxygen consumption: heart rate slows, blood is routed to the most essential locations (brain,
sensory organs, etc), and blood supply to the muscles may be shut off during long dives.
Instead,
these organisms effortlessly glide using buoyancy changes, and can resort to fermentation to
power their muscles if the myoglobin runs out.

Chapter 42 Circulation

Lauren and Nonye


1.
Describe the need for circulatory & respiratory systems due
to increasing animal body size.


Unlike large animals, small animals may not need a circulatory system because their interior cells are closer
together which allows oxygen to be absorbed more easily. Due to a high surface
-
to
-
volume ration, small flat or po
rous
animals do not need circulatory systems.


2.
Explain how a gastrovascular cavity functions in part as a circulatory system.


Such cavities provide inner cells with direct exposure to water. Organisms such as cnidarians and flatworms are
only two cell
layers thick allowing for all cells to be exposed to water for nutrients and gas exchange.


3.
Distinguish between open & closed circulatory systems. List the 3 basic components common to both systems.


In an open circulatory system, blood is blood is pu
mped from the heart through blood vessels but then it leaves
the blood vessels and enters different body cavities where the organs are bathed in blood. Within an open circulatory
system, blood flows slowly because there is no blood pressure after the blood

leaves the vessels.


On the other hand, in a closed system blood remains within the blood vessels, pressure is high, and as result blood
is pumped faster.

3 basic components



Circulatory fluid (blood)



Set of tubes (blood vessels)



Muscular pump (heart)


4.
List the structural components of a vertebrate circulatory system and relate their structure to their functions.



Blood
: used to carry dissolved materials and cells



Blood vessels
: carries materials and allows for exchange through the body



Heart
:

musc
le that moves blood in a distinct direction


5.
Using diagrams, compare and contrast the circulatory systems of fish, amphibians, non
-
bird reptiles, and mammals or
birds.


In three of the diagrams, red symbolizes oxygen
-
rich blood and blue symbolizes oxyge
n
-
poor blood.



















Fish have a two
-
chambered
heart and a single circuit of
blood flow

Amphibians have a three
-
chambered heart
and two circuits of blood flow:
pulmocutaneous

and
systemic.
With
double circulation, blood is delivered to
systemic organs under high pressure. There
is some mixing of oxygen
-
rich and
oxygen
-
poor blood within the si
ngle
ventricle.

Mammals have a four
-
chambered hear
t and double
circulation. Inside of the
heart, oxygen
-
rich blood is
kept separated from oxygen
-
poor blood.

6.
Distinguish between pulmonary and systemic circuits and explain the functions of each.


The pulmonary circuits lead to capillaries in the gas
-
exchange organs where blood picks up oxygen and releases
carbon dioxide before returning to the heart’s left atrium.


Most of the returning oxygen
-
rich blood is pumped into the syst
emic circulation that supplies all body organs and
then returns oxygen
-
poor blood to the right atrium through the veins.


7.
Explain the advantage of double circulation over a single circuit.

In

a

double circulation system there is no mixing of the oxyge
nated and deoxygenated blood so the blood is pumped to the
rest of the body with a higher concentration of oxygen than it would otherwise and at a higher pressure
.


8.
Define a cardiac cycle, distinguish between systole and diastole, and explain what cause
s the first and second heart
sounds.

Cardiac cycle
: the alternating contractions and relaxations of the heart


Systole is the stage of the heart cycle when the heart muscle contracts and the chambers pump blood but the diastole is
when the heart is relaxed

which allows the chambers to fill with blood.


The first sound is from when the blood recoils against a closed atrioventricular valve (AV) and the second sound is
when the blood recoils against the closed semilunar valves.


9.
Define cardiac outpu
t and describe two factors that influence it.

Cardiac output
: the volume of blood pumped per minute by the left ventricle of the heart


2 Factors

Heart rate

Stroke volume


10.
List the 4 heart valves, describe their location, and explain their functio
ns.

4 Heart valves

Bicuspid

between left atrium and left

ventricle

works as a trap door opening when
the oxygented blood needs to pass to
the left ventricle


Tricuspid

between right atrium and right

ventricle

anchored by strong fibers that

prevent

it from turning inside out.
Pressure generated by contractions

of ventricles close the AV valves,

keeping blood from flowing back

into the atria

Pulmonary semilunar

between right ventricle and

pulmonary trunk

prevents the back flow of blood

as it is pumped from the right

ventricle to the pulmonary artery

Aortic semilunar

between left ventricle and aorta

opens to let blood flow into the

aorta

and then closes to stop blood

from flowing back into the heart


11.
Define heart murmur and
explain its cause.

Heart murmur
:
an abnormal sound of the heart; sometimes a sign of abnormal function of the heart valves


Heart murmurs are usually caused by
new
development

of the heart
, infection,

or

wear
-
and
-
tear

of the muscle.




12.
Define sinoat
rial (SA) node and describe its location in the heart.

Sinoatrial node
:
a

small body of specialized muscle tissue
located
in the wall of the right atrium of the heart that acts as a
pacemaker by producing a contractile signal at regular intervals

13.
Explain how the pace of the SA node can be modulated by nerves, hormones, body temperature, and exercise.

Heart rate is a compromise regulated by the opposing actions of two sets of nerves. One speeds up the pacemaker and the
other slows it down.

-

As ne
rves become more sympathetic, heart rate goes up and when it becomes parasympathetic the
heart rate goes

-
Hormones secreted into the blood by glands influence the pacemaker like epinephrine (“fight
-
or
-
flight” hormone from the adrenal glands) which increas
es heart rate

-
As temperature increases, the rate of the pacemaker also increases and vise versa

-
Exercise increases heart rate, an adaptation which allows the circulatory system to provide extra
oxygen needed by the muscles hard at work


14.
Relate the st
ructures of capillaries, arteries, and veins to their functions.



Structure

Function

Capillaries

Thin walled

Easy for exchange

Arteries

Thick walled

To contain and control high

pressure

Veins

Thin and valved walls

To keep low
-
pressure blood flowing
towards
the heart


17. Blood flows more slowly through capillaries then through arteries and veins because capillaries provided more room
for blood to flow through. The surface area of a capillary is much larger than that of an artery or vein. Blood generally
flows at the sa
me rate throughout the body, so the greater the canal for the blood to flow through, the slower the fluid
moves.


18. Blood Pressure: the force of blood against arteries. Blood Pressure is measured in two numbers. Ex: 120/80

Systolic: the top number.
Generally the larger of the two numbers; measures the pressure in the heart when it contracts

Diastolic: bottom number. Generally the lower number; measures the pressure in the heart between each heartbeat.


19. Blood returns to the heart from lower extrem
ities against gravity with the assistance of movement; Skeletal muscles
contract, allowing blood to move upward (against gravity) through our veins. When we stop moving,

valves in our veins close, disabling blood to pour downward.


20. Capillary beds are
regulated by precapillary sphincters, which are bands of flat muscle that wrap around arterioles,
control the total amount of blood flowing in a particular capillary bed. Contraction of the sphincter shuts off blood flow
to a capillary bed, while relaxatio
n of the sphincter permits blood to flow.


21. Lymph is a clear, colorless liquid with a composition similar to blood plasma.

The lymphatic system aids the immune system in destroying pathogens and filtering waste so that the lymph can be
safely returned t
o the circulatory system. To remove excess fluid, waste, debris, dead blood cells, pathogens, cancer
cells, and toxins from these cells and the tissue spaces between them. The lymphatic system also works with the
circulatory system to deliver nutrients, o
xygen, and hormones from the blood to the cells that make up the tissues of the
body.

When it comes to defending the body, lymph nodes act as trap of unfamiliar particles.


22. Plasma is actually a yellow color and, while mostly composed of water, contains

other things such as proteins, salts,
lipids and glucose.


Plasma helps to regulate osmotic body pressure of liquids and it keeps pH at a constant level. It transports nourishing
substances, oxygen, carbon dioxide, and even damaging products of nitric com
pounds metabolism.


23. Erythrocytes: red blood cell; corpuscle; In humans, the mature form is a non
-
nucleated, yellowish, biconcave disk,
containing hemoglobin and carrying oxygen. The primary function of red blood cells is to carry oxygen from the lungs
to
the tissues around your body. As a secondary function, they are also a key player in getting waste carbon dioxide from
your tissues to your lungs, where it can be breathed out. RBC’s Flexible shape allow for easy maneuvering in and out of
capillaries an
d veins.


24. 5 Main Types of White Blood Cells:


NEUTROPHILS: defenders against bacterial and fungal infection and are present in large numbers in any
inflammatory reaction. They are capable of engulfing an invader by phagocytosis. Neutr
ophils are

attracted to the site of an injury or an invader within moments and are the primary component of inflammation.




EOSINOPHILS: primarily responsible for allergic reactions, making them a main component of asthma

reactions. They a
lso are also involved in the defense against outsized parasites that enter the body.


BASOPHILS: They are heavily involved in asthma attacks. During an allergic reaction, basophils will

migrate to the source of the reaction and may leave th
e blood and enter the tissues to perform their duty.


LYMPHOCYTE: T here are two common types of lymphocytes with somewhat different functions. B cells are
responsible for being modulated by antibodies. T cells, attack invaders by using what
is called cell

mediated immunity. Lymphocytes play a key role in the body's immune esponse by providing very specific defenses
against infection.

MONOCYTE: perform phagocytosis in a similar way that Neutrophils do. Second, they also function in harmony
with the T cells to identify and destroy pathogens.

25. Platelets Structure: fragments of cells, protein layer outside to stick tears in blood ves
sels, their granules emit other
protein to form a seal over the blood vessel, also made up of another protein in found in muscle tissue to help them
change shape when they are sticky.


26. LIFE CYCLE OF THE ERYTHROCYTE : Production of New RBC's
-

Erythrop
oiesis (takes 4 days)



1. Hemocytoblasts
-

Stem cells in the bone marrow from which all blood cells form.



2. Proerythroblasts
-

are produced by the division and differentiation of stem cells.



3. Basophilic (ea
rly) erythroblasts
-

During this stage in erythropoiesis hemoglobin synthesis begins.



4. Intermediate erythroblasts
-

At this time, we see the accretion of hemoglobin due to its continued
synthesis.




5. Late erythroblasts
-

During this stage the nucleus is extruded from the cell.



6. Reticulocyte
-

These cells exhibit a net
-
like form or reticulum in their cytoplasm when stained. A little
number of reticulocytes are foun
d in the circulation.


7. Mature erythrocytes
-

At this final stage of maturation there is a loss of ribosomes. These cells enter the
circulation.


The Breakdown By Phagocytotsis:


* The chemical components of the RBC ar
e broken down within vacuoles of the macrophages due to the
action of lysosomal enzymes. The hemoglobin of these cells is degraded into:***


* a. Globin which is further digested down to amino acids. These amino acids can then be utili
zed by the
phagocytes for protein synthesis or released into the blood.***


* b. Heme molecules go through a series of changes. The macrophages convert heme into biliverdin

and
then bilirubin.

Bilirubin is released into the bl
ood where it forms a complex with blood albumin (bound bilirubin). *


* c. Iron is removed from heme molecules in the phagocytes. The macrophages can store iron or

release it to the blood. *

http://faculty.ucc.edu/biology
-
potter/life_cycle_of_the_erythrocyte.htm**




27. Erythrocyte is produced when oxygen levels are decreased. The kidneys detect this and therefore secrete the
hormone erythropoietin. This hormone ultimately produc
ed more red blood cells.


28. A heart attack occurs when blood supply is cut off to the heart, possibly from a blood clot. Persons who have a heart
attack may have symptoms of chest pain, or breathlessness. A stroke is when blood supply is cut off to t
he brain.
Persons having a stroke, generally feel no pain.



29. Low
-
Density Lipoproteins (LDLs): When too much LDL (bad) cholesterol circulates in the blood, it can slowly build up
in the inner walls of the arteries that feed the heart and brain. It can

form plaque, a thick, rigid

deposit that can narrow the arteries and make them less flexible. This condition is known as atherosclerosis. High
-
Density Lipoproteins (HDL): The good" cholesterol, because high levels of HDL seem to shield from heart attack.

Low
levels of HDL also increase the risk of heart disease. Doctors think that HDL tends to carry cholesterol away from the
arteries and back to the liver, where it's passed from the body. Some experts believe that

HDL removes extra cholesterol from arter
ial plaque, slowing its buildup.


30. Here are several risk factors that have been correlated with heart disease; some are controllable, others are not.
Uncontrollable risk factors include:


-

Male sex


-

Older age


-

Family history of heart disea
se


-

Post
-
menopausal


-

Race (African Americans, American Indians, and Mexican Americans are


more likely to have heart disease than Caucasians)


Still, there are many heart disease risk factors that can be controlled. By making changes in your lif
estyle, you can
actually reduce your risk for heart disease. Controllable risk factors include:



-

Smoking.


-

High LDL, or "bad" cholesterol and low HDL, or "good" cholesterol.


-

Uncontrolled hypertension (high blood pressure).


-

Physical inact
ivity.


-

Obesity (more than 20% over one's ideal body weight).


-

Uncontrolled diabetes.


-

High C
-
reactive protein.


-

Uncontrolled stress and anger.









































Rebecca Ast, Corey Forman, & Sydney Saltzman Present:

Chapter 43: The Body’s Defenses

Nonspecific Defenses Against Infection

1.

Nonspecific defense does not distinguish between infectious agents. Lines of nonspecific defense
include: skin and mucous membranes and their secretions, phagocytic white blood cells, a
ntimicrobial
proteins and the inflammatory response.


2.

A)

Innate immunity

is nonspecific, and is with organisms from birth. It involves protective barriers such
as skin and mucous membranes.
Acquired immunity

develops in an organism after they are exposed t
o a
pathogen (either via vaccination or infection). White blood cells called lymphocytes create defensive
proteins called antibodies which allow lymphocytes to recognize and quickly eliminate the pathogen
should it enter the body again. Both types of immun
ity are life
-
long.

B
) Humoral immunity

involves the production of antibodies present in blood plasma a
nd lymph, and the
activation of B cells.
Cell
-
mediated response

involves T cells and their ability to provide immunity to
infection when transferred among individuals.


3.

The physical barrier of the skin is enforced by several chemical defenses. Human sweat
glands secrete
chemicals that give the skin a pH level between 3 and 5 to inhibit microbial colonization on skin. Saliva
and tears also work to wash away microbes from skin, they contain an antimicrobial protein called
lysozyme, which digests the cell wall
s of bacteria, thus destroying the bacteria and preventing it from
entering the body. Mucus (found in mucous membranes) traps microbes and also prevents them from
entering vital organs such as the lungs


4.

Phagocytosis

is the ingestion of invading pathogens
by certain types of white blood cells, or leukocytes.
The four types of leukocytes responsible for phagocytosis are:
neutrophils

(which make up between 60
% to 70% of white blood cells, and self destruct as they destroy pathogens),
monocytes
(which circula
te
the blood until they move into tissues),
macrophages
(the largest phagocytic cells), and
eosinophils

(which defend against large parasitic invaders).


5.

Interferons

are proteins secreted by cells that are infected with a virus. These proteins alert neigh
boring
cells to produce chemicals that inhibit viral reproduction, which prevents the other cells from becoming
infected with the virus.


6.

The inflammation response is triggered by an injury such as an open cut, or by the entry of foreign
microbes into the body. Chemical signals that arise from surrounding cells, or the invader itself initiate
inflammation signaling for the dilation and incre
ased permeability of surrounding capalaries.This causes
increased blood flow to the injury. The increased blood flow allows for clotting agents to reach the
injury in order for healing to begin.


7.

The increased blood flow that occurs at the injury site duri
ng the inflammatory response allows for
phagocytic white blood cells to reach the damaged tissues. The phagocytic cells are attracted to the
injury site by chemical signals released by infecting bacteria, as well as by chemokines, which are
secreted by mon
ocytes and blood vessel endothelial cells. Once they reach the injury site, phagocytic
cells consume and destroy the pathogens and their products, and “clean up” damaged cells.


8.

Natural killer cells

destroy body cells that are infected by a virus. They do
not phagocytose, or ingest
infected cells as phagocytes do. Instead, natural killer cells attack the infected cell’s membrane and
cause the cell to lyse, or split open.


9.

Septic shock

occurs when a pathogen causes a severe inflammatory reaction from white b
lood cells.
Leukocytes release an excess of pyrogens (chemicals that raises the body temperature in order to inhibit
the growth of microbes), which causes a (deadly) high fever. Increased blood flow to the infection
results in low blood pressure, until blo
od in unable to circulate through the body. Septic shock results in
death in 50% of cases.


How Specific Immunity Arises

10.


An

antigen

is a foreign molecule that causes a response from lymphocytes, usually found on the surface
of foreign invaders.

Antibodies

are proteins secreted by B lymphocytes in order to signal an immune
response and recognize antigens.


11.

An
epitope

is found on the surface of an
antigen
, and is the region of the antigen that is chemically
recognized by antibodies


12.


The antigen receptors o
n lymphocytes are very specific as to the antigens they recognize. The specific
receptors present on each lymphocyte are determined by segments of antibody genes and receptor genes
that recombine to form a single functional gene that responds to a polypept
ide of an antibody, so each
receptor has a single specific antibody it recognizes. This process occurs early in the lymphocyte’s
development, before the lymphocyte differentiates into a B or T cell.


13.


The
primary immune response

occurs the first time the b
ody is exposed to a specific antigen. The
primary immune response takes 10 to 17 days and involves the differentiation to lymphocytes to respond
to a specific antigen. The lymphocytes generate plasma cells which produce antibodies which recognize
the antig
en and remove it from the body. The
secondary immune response

occurs when the body is
exposed to the same antigen for a second time. This time more of the antibodies are generated faster.
The antibodies produced by the secondary immune response are also mo
re effective at tracking and
terminating the antigen than then the primary response antibodies.


14.

Immunological memory
, or the immune system’s ability to generate the secondary immune response,
occurs because a lymphocyte undergoes division when in is acti
vated by an antigen. The lymphocyte
divides and differentiates into
effector cells
, which attack the specific antigen during the current
infection, and
memory cells

which bear receptors for the specific antigen. The memory cells are able to
recognize and c
ombat the antigen should it invade the body again in the future.


15.

The major
histocompatibility complex
, or MHC, are genes that code for cell surface glycoproteins
present on cells native to the body. Each individual human being has a unique set of genes en
coding
their MHC glycoproteins. The MHC is the cause of tissue rejection in organ transplants. The MHC
molecules are responsible for presenting antigens to T cells, so if they do not recognize foreign markers
on transplant tissue cells, the transplant tiss
ue will be targeted for immune response. The variation of
MHC genes among humans insures that there will be some members of a population than will survive an
epidemic because their MHC genes will recognize the pathogen antibodies and initiate an immune
res
ponse.


16.

Cytotoxic T cells

respond to class I MHC molecules and kill the infected cells.
Helper T
-
Cells
respond to
class II MHC molecule production and are involved in antibody production.


17.

Class I MHC molecules

are present in all types of cells and presen
t fragments made by infectious
microbes such as viruses to cytotoxic T cells.
Class II MHC molecules

are made by macrophages and B
cells, and ingest and destroy pathogens then present their remains to helper T cells. Helper T cells
release chemicals that s
ignal for other cells to fight the pathogen.

Immune Responses

18.


Humoral immunity deals with infection in the blood and body tissues. Cell
-
mediated immunity deals
with already
-
infected body cells. Humoral immunity mostly involves B cells, while cell
-
mediated

immunity is mostly T cells.


19.

Humoral immunity deals with infection in the blood and body tissues. Cell
-
mediated immunity deals
with already
-
infected body cells. Humoral immunity mostly involves B cells, while cell
-
mediated
immunity is mostly T cells.


20.

CD4

is a T cell surface protein. In helper T cells, it binds to the class II MHC protein that a phagocyte
presents. This link between the two cells helps keep them joined while the helper T cell activates. CD8
is a protein present on the surface of cytotoxic
T cells. It binds to the class I MHC protein that an
infected or abnormal cell presents. This link helps keep the two cells joined while the cytotoxic T cell
activates.


21.


Because tumor cells are abnormal, they can be identified as foreign by their class I
MHC proteins. In
this case, the class I MHC proteins are presenting fragments of tumor antigen. In this way, cytotoxic T
cells destroy tumor cells just as they would any other infected or abnormal cell. However, some cancers
and viruses, like the Epstein
-
B
arr virus, reduce the amount of class I MHC proteins that the cell shows
in order to avoid detection. In this case, natural killer cells lyse the tumor cells. Because natural killer
cells are part of the body’s nonspecific defense system, they don’t need t
o recognize class I MHC
proteins.


22.

In primary response, the phagocytes recognize foreign cells and devour them. They then present the
foreign proteins for the helper T cells to recognize. In secondary response, the antigen is recognized by
memory helper T
cells, which stimulate memory B cells. The memory B cells then portray the protein so
that plasma cells know what kind of antibody to secrete.


23.

Antibodies have two identical antigen
-
binding sites, specific for the epitope that stimulated its
production. A
n epitope is a specific protein formed by specific antigens. Most bacteria have multiple
kinds, so multiple kinds of antibodies need to be employed. Antibodies can destroy or disactivate
antigens through neutralization, opsonization, and aggultination.

24.













The variable portion of antibodies varies depending on what antigen they are designed to link with. They
are the antigen
-
bonding sites. The constant portion is more or less the same amino acid sequence for
every antibody. This is so that all phag
ocytes can easily bond to them.


25.

A monoclonal antibody culture is a culture of antibodies produced in a lab by a single B cell clone.
Since all of the antibodies in a monoclonal culture are identical, they are all specific for the same epitope
on an antige
n. Because of this, they can be used to tag antigens.


26.

Neutralization is when an antibody simply binds to an antigen to block its activity. For example, an
antibody may neutralize a virus by attaching to the molecules that the virus uses to infect its host

cell. In
opsonization, bound antibodies make it easier for macrophages to attach, and thus easier to devour,
microbes. In agglutanation, the two antigen
-
bonding sites on an antibody are attached to two different
microbes. This makes chains and clumps all
of the microbes into one spot. This makes it easy for
macrophages to take out many microbes at once. All of these processes involve antibody attachment and
macrophage devouring.

Immunity in Health and Disease

27.


Active immunity is when the immune system depends on the response of the infected person’s own
immune system. Active immunity can be acquired naturally or artificially (vaccines) an example of
active immunity is when somebody requires chicken pox, or gets

the vaccine.

Passive immunity is when antibodies are transferred from one individual to another. This occurs
naturally when IgG antibodies of a pregnant woman cross the placenta to her fetus. Also, IgA antibodies
are passed from mother to nursing infant i
n breast milk.


28.

Because the blood group antigens are polysaccharides they induce T
-
independent responses, which elicit
no memory cells. As a result, each response is like a primary response and generates IgM anti
-
blood
-
group antibodies. W
ith the Rh factor, if the positive and negative Rh factors are crossed the outcome
will be deadly.


29.

The Rh factor is able to cause trouble because antibodies produced to it are of the IgG class. This means
that if a mother is Rh
-
negative but has a fetus wh
o is Rh
-
positive, or the other way around, it could be
potentially dangerous. If their blood is crossed through the placenta than the mothers immune system
may attack the fetus’s blood therefore killing the fetus. To prevent this, the mother is injected wi
th anti
Rh bodies after delivering first Rh
-
positive baby, this is passively immunized to eliminate Rh antigen
before her own response system responds and generates.

30.

To minimize rejection, attempts are made to match the MHC of the tissue donor and recipie
nt as closely
as possible. Usually siblings are the closest matches. In addition to a close match, various medicines are
necessary to suppress the immune response to the transplant. In bone marrow transplants it’s the same as
the other transplant except th
e recipient is typically treated with irradiation to eliminate his or her own
marrow cells. This leaves little chance to graft rejection


31.

When the plasma cells secrete IgE specific for pollen allergies. Some of the IgE antibodies attach by
their tails to m
ast cells present in connective tissues. Later, when pollen grains enter the body, they
attach to the antigen
-
binding sites of mast cell
-
associated IgE crosslinking, adjacent antibody molecules.
His event induces the mast cell to degranulate
-

That is to re
lease histamine and other inflammatory
agents from vesicles called granules. Histamines cause dilation and increased permeability of small
blood cells. These inflammatory events lead to typical allergy symptoms.


32.

Occurs when widespread mast cell degradnula
tion triggers abrupt dilation of peripheral blood vessels,
causing precipitous drop in blood pressure. People with severe hypersensitivities carry syringes
containing the hormone epiphrine, which counteracts this allergic response.


33.

Systemic lupus erythema
tosus, Rheumatoid arthritis, and insulin
-
dependent diabetes mellitus.
Mechanisms that lead to autoimmunity are not fully understood. Autoimmune disease likely arises from
some failure in immune regulations. Once thought it was self
-
reactive lymph nodes, no
t true because
even healthy individuals have self
-
reacting lymph nodes. One intriguing finding is that the inheritance of
particular MHC alleles is associated with susceptibility to certain autoimmune diseases.


34.

Many inborn deficiencies affect the function

of either humoral or cell mediated immune defenses.
Inborn is when you are born with the autoimmune deficiency. Acquired is when the problem is
developed over time.


35.

A retrovirus called human immunodeficiency virus (HIV) causes AIDS. Two strains HIV
-
1 and

HIV
-
2,
HIV
-
1 is the more widespread strains that are more virulent. Both strains infect cells that bear surface
CD4 molecules, CD4 cells are located on help T cells and enhance the binding between those cells and
class 11 MHC
-
bearing antigen
-
presenting ce
lls. Entry of virus requires CD4 on surface of susceptible
cell and second protein molecule, a coreptor.
















Chapter 44


Controlling the Internal Environment Objectives



Rachel Jacob

Daniel Nagrundy

1.)
Define osmoregulation and excretion

Osmoregulation
-

How animals regulate solute balance and the gain and loss of water

Excretion
-

How animals get rid of the nitrogen
-
containing waste products of metabolism such as urea


2.)
Distinguish between osmoregulators and osmoconformers. Explain why o
smoregulation has an energy cost.

An osmoregulator is an animal that must control its internal osmolarity, because its body fluids are not isosmotic with
the outside environment. Osmoregulation helps and animal maintain a constant concentration of solutes
in its body. Its
internal osmolarity is equal to that of its environment so there is no tendency to gain or lose water. On the other hand,
animals can be conformers. OsmoConformers are animals that do not actively adjust its internal osmolarity to its
sur
roundings. An example of this is osmoconformers. Marine invertebrates, such as spider crabs, are osmoconformers.
It discharges excess water if it lives in a hypoosmotic environment or takes in water to offset osmotic loss if it inhabits a

hyperosmotic env
ironment. The energy cost depends on the difference in osmolarity from the organisms surroundings,
how easily water and solutes can move across the animal’s surface, and on how much membrane
-
transport work is
required to pump solute.


3.)
Discuss the osmo
regulatory strategies of marine animals.


Because some marine animals spend part of their loves in salt water and fresh water, the osmoregulatory strategies of
marine animals is to use mechanisms of osmoregulation to maintain a constant concentration of so
lutes in its blood and
interstitial fluid. They do this throughout the change in “osmotic environment.”

4.) Explain how the osmoregulatory problems of freshwater animals differ from those of marine animals.

Fresh water animals


-
constant gain in water (os
mosis) and lose salts (diffusion) because osmolarity of internal fluids are much greater
than surroundings


-
contractile vacuoles that pump out excess water


-
maintain water balance by excreting large dilute urine and manage salt by regaining lost salt in
food and active
uptake of surrounding


5.)
Describe anhydrobiosis as an adaption that helps tardigrades and nematodes to survive periods of dehydration

Anhydrobiosis
-

aquatic invertebrates that live in temporary ponds and films of water around soil particl
es lose almost all
their body water and survive in dormant state when their habitats dry up. These animals are not doomed due to
dehydration.

Tardigrades, otherwise known as water bears, normally contain 85% water weight but when it reaches its dehydrated

state, it can have less than 2% water, in its dehydrated state; it will survive as inactive and dry for decades. When water
is added at this state, the tardigrades become active once again.

Anhyydrobiatic

round worms, otherwise known as nematode, keep their cell membranes intact by containing large
amounts of sugar called Trehalose
-

protects cell by replacing water associated with proteins and membranes.


6.)
Describe some adaptations that reduce water los
s in terrestrial animals

An adaptation that reduces water loss in terrestrial animals is that they have body coverings that help prevent
dehydration (shell
-
snails; waxy layer
-
insects.) another adaptation is that these animals are nocturnal. This reduces
ev
aporative water loss when animal take advantage of low temperatures and higher relative humidity of night air.







7.)
Describe the ultimate function of osmoregulation.

The ultimate function of osmoregulators is for an animal to control its internal envi
ronment because bodily fluids are
not isoosmotic with the outside environment. If they live in hypoosmotic environment, animals must discharge excess
water. If in hyperosmotic environment, must take in water to offset osmotic loss. It allows animals to liv
e in
uninhabitable environment for osmoconformers and maintain internal osmolarities different from seawater.



8.)
Explain the role of transport epithelia in osmoregulation and excretion.

Transport epithelia
-

layer(s) of specialized epithelial cells that

regulate solute movement. *most important feature of all
transport epithelial is its ability to move specific solutes in controlled amounts in a particular direction.



9.)
Describe the production and elimination of ammonia
.

Ammonia is a very small toxic
molecule. Animals release ammonia when nucleic acids and proteins broken apart for
energy or converted to carbohydrates or fats, enzymes remove nitrogen in the form of ammonia. Ammonia excretion is
common to aquatic species because animals that do this nee
d access to a lot of water because ammonia is very soluble
but can only be tolerated at very low concentration.


10.)
Compare strategies to eliminate waste as ammonia, urea, and uric acid.

Ammonia
-

most aquatic animals, many fish; soluble in water

Urea
-

m
ammals, most amphibians, sharks, some bony fish, turtles and marine fish; low toxicity because ammonia stored
with carbon dioxide; can transport and store at high concentrations and reduce amount of water needed

Uric acid
-

birds, insects, many reptiles, la
nd snails; very litter water loss therefore great advantage for animals with little
access to water


11.)
Compare the amounts of nitrogenous waste produced by endotherms and ectotherms and by predators and
herbivores
.

Endotherms eat more food therefore pro
ducing more nitrogenous wastes than ectotherms. Predators excrete more
nitrogenous waste than herbivores because predators extract their protein from meat whereas herbivores extract their
proteins from plants. Plants contain lipids and carbohydrates for pr
otein which does not provide an excessive amount of
nitrogenous waste.


12.) Describe the key steps in the process of urine production.

Nearly all excretory systems produce urine by a two
-
step process. The first step is where body fluid such as blood and
hemolymph is collected and then the fluid is adjusted by the
secretion

of solutes. Initially, fluid collection goes through
the process of filtration through a selectively permeable membrane. Then certain molecules such as salts, sugars, amino
acids, and n
itrogenous wastes are forced into the system by hydrostatic pressure. Eventually, the fluid is combined and
is known as the
filtrate
.


13.)
Describe how a flame
-
bulb (protonephridial) excretory system functions.


Unlike any other species, Flatworms have a
specific excretory system called
protonephridia
, which is a network of dead
-
end tubules lacking internal openings. A special unit called the flame bulb closes of these branches of tubules and the
flame bulb’s main function is to beat its cilia that project
s into these tubules. As a result, the beating of cilia draws water
and solutes and moves the fluid into the tubule system. The excretion of this fluid comes next with the urine exiting
through pores called
nephridiospores
.





14.)
Explain how the metanep
hridial excretory tubule of annelids functions. Compare the structure to the protonephridial
system.

Annelids such as earthworms have an excretory system called the
metanephridium

which has internal openings that
collect body fluids. An earthworm is split
into segments with each segment containing a pair of metanephridia, which
collects body fluids. The fluid then empties through a coiled collecting tubule called a nephridiopore. A reason why
earthworms need a great amount of water is because their urine is

very dilute which means it is mainly composed of
water. Thus, most of their water absorption comes from the water in the soil.



15.)
Describe the Malpighian tubule excretory system of insects.


Insects have specific organs called
Malpighian tubules

that
open in the digestive tract so that the transport of outer
fluids combine with circulatory fluid called
hemolymph
. Most of the solutes that are in the tubules flows with water into
the rectum where the nitrogenous wastes are passed through the rectum and t
he water and solutes are recycled.


16.)
Using a diagram, identify and give the function of each structure in the mammalian excretory system.

The
inferior vena cava

is a large vein that carries deoxygenated blood from the bottom half of the body into the h
eart.
The aorta then pumps oxygenated blood throughout the body. The inferior vena cava is one of the veins that supplies
blood directly to the kidneys by the
renal vein
. This occurs so that the kidneys (filtration organs) will remove byproducts
such as
am
monium

and
urea
. The byproducts then move into a duct called the
ureter
, which transfers the byproducts to
the urinary bladder. Thus, urine is formed and it exits the body through the
urethra

tube.






























17.)
Using the diagram,
identify and describe the function of each region of the nephron.

The
nephron

is the main functional unit of the kidney. It is made up of capillary veins called the
glomerulus

and a single
long tubule. The swelling of the Bowman’s capsule occurs when the t
ubule swells into a cup
-
shape around the
glomerulus. The fluid is forced into the Bowman’s capsule and cells on the capsule are porous only to water and solutes.
The filtrate of fluid then goes through a long course by passing through the proximal tubule,
the
loop of Henle
, and the
distal tubule
. Then the filtrate empties into the
collecting duct

where it is excreted in the form of urine.


























18.)
Describe and explain the relationship among the processes of filtration, readsorption,
and secretion in the
mammalian kidney.


First of all, there are many relationships between filtration, reabsorption, and secretion in the mammalian kidney.
Filtration of the blood passes through the nephron while containing salts, glucose, and water. The
e
pithelium

which
lines the tubes in the nephron processes the filtrate as it passes through. Most if not all the nutrients, sugar, and water i
s
absorbed into the blood and byproducts are then secreted by the kidneys.


19.)
Distinguish between cortical and j
uxtamedullary nephrons. Explain the significance of the juxtamedullary nephrons
of birds and mammals.


Cortical nephrons

make up most of the kidney’s nephrons and unlike
juxtamedullary nephrons
, cortical nephrons have
shorter loops of Henle and are found o
n only the outer region of the kidney, which is called the renal cortex.
Juxtamedullary nephrons are found in the renal medulla, which is the inner region of the kidney and they are longer.
Only mammals and birds have juxtamedullary nephrons; they serve as

a water regulator in order to conserve the most
amount of water.


20.)
Explain how the loop of Henle enhances water conservation by the kidney.

The Reabsorption of water continues as the filtrate passes through the loop of Henle. The loop of Henle is ver
y
permeable to water, and a lot less permeable to other solutes. Thus, the kidney reabsorbs the water from the filtrate.


21.)
Explain how the loop of Henle functions as a countercurrent multiplier system.

As the filtrate moves from the descending limb t
o the ascending limb, the epithelium collects salt from the filtrate
because it is very permeable to solutes. As the filtrate ascends, the salt that is collected in the descending limb slowly
diffuses out and the filtrate is hypotonic to the fluid.


22.)
D
escribe the nervous and hormonal controls involved in the regulation of the kidney.


When the body loses a lot of water, large amounts of
antiduretic hormone

or ADH is released into the bloodstream.
ADH is a hormone that regulates water balance. The rennin
-
angiotensin
-
aldosterone system or
RAAS

also regulates
water balance. A specialized tissue called juxtaglomerular apparatus or
JGA

regulates blood pressure levels by releasing
an enzyme called rennin. This enzyme converts certain proteins into a hormone ca
lled angiotensin II, which causes a
higher absorption of salt and water. Thus, the salt and water raises blood pressure.
Aldosterone

is another hormone
that increases salt and water absorption

in order to increase blood pressure. When blood pressure is abo
ve normal
levels, a hormone called
atrial natriuretic

shuts down RAAS and aldosterone in order to regulate the BP levels.



23.)
Describe the structural and physiological adaptions in the kidneys of nonmammalian species that allow them to
osmoregulate

in different environments.

Birds are an example nonmammalian species that cannot concentrate their urine to the extent that mammals can since
their loops of Henle are much shorter. Another adaptation is found in beavers which have very dilute urine becaus
e they
spend a lot of time in water. That means that the water they take in is not reabsorbed. Reptiles also have dilute urine
since they only have cortical nephrons, which means that they have short loops of henle. Freshwater fish on the other
hand excret
e large amounts of water since they are hypertonic to their environment. Since Salt water fish are hypotonic
to their environments, the produce very little urine and only excrete the urine when they have a large amount of salt
build up in their bodies.















Jeremy Applebaum and Emilie Doyle

Chapter 45: Hormones and the Endocrine System

1.

The nervous system conveys high
-
speed signals along specialized cells called neurons. These rapid
messages function in such activities as the movement of body parts

in response to sudden environmental
changes like jerking your hand away from a flame, for example. The endocrine system conveys slower
means of communication that regulate other biological processes, such as the maturation of a butterfly.
This kind of inf
ormation is relayed by hormones.

2.

Neurosecretory cells are specialized nerve cells that secrete chemicals. The chemicals function as
hormones in the endocrine system and signals in the nervous system, integrating the endocrine and
nervous systems together.

One hormone, epinephrine, is the “fight or flight” hormone in the endocrine
system, but also a neurotransmitter that conveys messages between neurons in the nervous system.

3.

A receptor, or sensor, detects a stimulus and sends information to a control cent
er. After comparing the
incoming information to a set point, the control center sends out a signal that directs an effector to cause
the body’s response. In endocrine and neuroendocrine pathways, this outgoing signal, called an efferent
system, is a hormon
e or neurohormone, which acts on particular effector tissues and brings about
specific physiological or developmental changes. The three types of simple hormonal pathways

simple
endocrine pathway, simple neurohormone pathway, and simple neuroendocrine path
way

include these
basic functional components. In a simple endocrine pathway, a stimulus informs a receptor protein of a
change in an internal or external variable, which then alerts an endocrine cell which releases a hormone
into the bloodstream as an eff
erent signal that elicits a response from the target effectors.

4.

The constant concentration of calcium ions in the blood is an example of negative feedback that
maintains homeostasis. This feedback loop is controlled by the antagonistic (opposite) actions
of two
hormones, calcitonin and parathyroid hormone (PTH). Excess calcium in the blood triggers the secretion
of calcitonin, which decreases the calcium level. When the calcium level gets too low, secretion of PTH
causes it to rise.

5.

The production of milk
by a nursing mother is an example of positive feedback, namely a loop in which
the output of a mechanism enhances the input of a mechanism, therefore producing more of the output.
In the case of milk production, the sucking on the nipple causes a nervous s
ignal called the
hypothalamus trigger to release the hormone oxytocin from the pituitary gland which ultimately
produces milk.

6.

The three major classes of molecules that function as hormones in vertebrates are proteins and peptides,
amines derived from
amino acids, and steroids, a type of lipid.

7.

The three key events involved in signaling by vertebrate hormones are reception (signal molecule binds
to a specific receptor protein), signal transduction (the activation of a specific receptor and alteration in

molecules to elicit a chemical response), and response (change in cell’s behavior).

8.

Depending on the signal molecule and the molecules present in a target cell, a signal
-
transduction
pathway may lead to responses in either the cytoplasm (the activation o
f an enzyme, for instance) or the
nucleus (usually involving the regulation of specific genes).

9.

Because different types of cells have different collections of molecules (especially proteins), the same
signal can bring about different responses in differen
t target cells. A single type of molecule, for
example the neurotransmitter called acetylcholine, can produce different responses in different target
cells. Different responses may result because the receptors are different or because signal
-
transduction
p
athways within the target cell are different.

10.

Intracellular receptors usually perform the entire task of transducing the signal within the target cell. A
chemical signal activates the intercellular receptor, which directly trigger’s the cell’s response. In

almost
every case, the intracellular receptor activated by a lipid (cell membrane)
-
soluble hormone is a
transcription factor, and the response is a change in gene expression. Most intracellular receptors are
located in the nucleus. The hormone
-
receptor co
mplexes bind to specific sites in the cell’s DNA and
stimulate the transcription of specific genes.

11.

Local regulators convey messages between neighboring cells, a process referred to as paracrine
signaling. Local regulators can act on nearby target cells w
ithin seconds or milliseconds, eliciting
responses more quickly than hormones can. Some local regulators have cell
-
surface receptors; others
have intracellular receptors. Binding of local regulators to their receptors triggers events within target
cells si
milar to those elicited by hormones. Among peptide/protein local regulators are cytokines, which
play a role in immune responses, and most growth factors, which stimulate cell abundance and
differentiation. Another important local regulator is the gas nitr
ic oxide (NO). When blood oxygen level
falls, endothelial cells synthesize and release NO. NO activates an enzyme that relaxes neighboring
smooth muscle cells, dilating the walls of blood vessels and improving blood flow to tissues. Local
regulators called

prostaglandins (PGs) are modified fatty acids derived from lipids in the plasma
membrane. In semen that reaches the female reproductive tract, PGs trigger the contraction of the
smooth muscles of the uterine wall, helping sperm to reach the egg. PGs secre
ted by the placenta cause
the uterine muscles to become more excitable, helping to induce uterine contractions during childbirth.
Other PGs help induce fever and inflammation, and intensify the sensation of pain. PGs also help
regulate the aggregation of p
latelets, an early stage in the formation of blood clots. In the respiratory
system, two prostaglandins have opposite effects on the smooth muscle cells in the walls of blood
vessels serving the lungs. Prostaglandin E signals the muscle cells to relax, dil
ating the blood vessels
and promoting oxygenation of the blood. Prostaglandin F signals the muscle cells to contract,
constricting the vessels and reducing blood flow through the lungs.

12.

The hypothalamus integrates vertebrate endocrine and nervous function
. This region of the lower brain
receives information from nerves throughout the body and from other parts of the brain and then initiates
endocrine signals appropriate to environmental conditions. The hypothalamus contains two sets of
neurosecretory cells

whose hormonal secretions are stored in or regulate the activity of the pituitary
gland.

13.

The pituitary gland is located
at the base of the hypothalamus. The posterior pituitary stores and secretes
two hormones produced by the hypothalamus. The long axons

of these cells carry the hormones to the
posterior pituitary. The anterior pituitary consists of endocrine cells that synthesize and secrete at least
six different hormones directly into the blood.

14.

Several of the hormones that are secreted by the anterior

pituitary hormones other endocrine glands as
their targets. Hormones that regulate the function of endocrine glands are called tropic hormones. They
are particularly important in coordinating endocrine signaling throughout the body. The anterior
pituitary

itself is regulated by tropic hormones produced by a set of neurosecretory cells in the
hypothalamus. Some hypothalamic tropic hormones (releasing hormones) stimulate the anterior pituitary
to release its hormones. Others (inhibiting hormones) inhibit hor
mone secretion.

15.

The thyroid gland produces two very similar hormones derived from the amino acid tyrosine:
triiodothyronine (T3), which contains three iodine atoms, and thyroxin (T4), which contains four iodine
atoms. In mammals, the thyroid secretes main
ly T4, but target cells convert most of it to T3 by removing
one iodine atom. Although the same receptor molecule in the cell nucleus binds both hormones, the
receptor has greater affinity for T3 than for T4. It is primarily T3 that brings about responses
in target
cells. The thyroid plays a crucial role in vertebrate development and maturation. The thyroid is equally
important in human development. The thyroid gland has important homeostatic functions. In adult
mammals, thyroid hormones help to maintain no
rmal blood pressure, heart rate, muscle tone, digestion,
and reproductive functions. Throughout the body, T3 and T4 are important in increasing the rate of
oxygen consumption and cellular metabolism. Too much or too little of these hormones can cause
serio
us metabolic disorders. Hyperthyroidism is the excessive secretion of thyroid hormones, leading to
high body temperature, profuse sweating, weight loss, irritability, and high blood pressure. An
insufficient amount of thyroid hormones is known as hypothyro
idism. This condition can cause
cretinism (hindered skeletal growth and mental development) in infants. Adult symptoms include weight
gain, lethargy, and cold intolerance. A deficiency of iodine in the diet can result in goiter, an
enlargement of the thyro
id gland. Without sufficient iodine, the thyroid gland cannot synthesize
adequate amounts of T3 and T4. In addition to cells that produce T3 and T4, the mammalian thyroid
gland produces calcitonin. This hormone acts to maintain calcium homeostasis.

16.

Rigoro
us homeostatic control of blood calcium level is critical because calcium ions (Ca2+) are essential
to the normal functioning of all cells. If blood Ca2+ falls substantially, skeletal muscles begin to contract
convulsively, a potentially fatal condition ca
lled tetany. In mammals, parathyroid hormone and
calcitonin play a major role in maintaining the calcium ion concentration in blood.When blood Ca2+
falls below the set point, parathyroid hormone (PTH) is released from four small structures, the
parathyroid

glands, embedded on the surface of the thyroid. In bone, PTH induces specialized cells
called osteoclasts to decompose the mineralized matrix of bone and release Ca2+ into the blood. In the
kidneys, it promotes the conversion of vitamin D to its active ho
rmonal form, which stimulates the
uptake of Ca2+ from food. A rise in blood Ca2+ above the set point promotes release of calcitonin from
the thyroid gland. Calcitonin exerts effects on bone and kidneys opposite those of PTH and thus lowers
blood Ca2+ level
s.

17.

Clusters of endocrine cells, the islets of Langerhans, are scattered throughout the exocrine tissues of the
pancreas. Each islet has a population of alpha cells, which produce the hormone glucagon, and a
population of beta cells, which produce the horm
one insulin. Both hormones are secreted directly into
the circulatory system. Insulin and glucagon are antagonistic hormones that regulate the concentration of
glucose in the blood. When blood glucose exceeds the necessary level, insulin is released and lo
wers
blood glucose. When blood glucose falls below this level, glucagon is released and its effects increase
blood glucose concentration. Insulin lowers blood glucose levels by stimulating all body cells to take up
glucose from the blood. Insulin also decr
eases blood glucose by slowing glycogen breakdown in the
liver and inhibiting the conversion of amino acids and glycerol to glucose.

18.

Diabetes mellitus is perhaps the best
-
known endocrine disorder. It is caused by a deficiency of insulin or
a depressed res
ponse to insulin in target tissues. There are two types of diabetes mellitus with very
different causes, but each is marked by high blood glucose. Type I diabetes mellitus (insulin
-
dependent
diabetes) is an autoimmune disorder in which the immune system de
stroys the beta cells of the pancreas.
Type I diabetes usually appears in childhood and destroys the person’s ability to produce insulin. The
treatment is insulin injections, usually several times a day. Type II diabetes mellitus (non
-
insulin
-
dependent dia
betes) is characterized by deficiency of insulin or, more commonly, by a decreased
responsiveness to insulin in target cells, due to some change in insulin receptors. This form of diabetes
occurs usually after age 40, and the risk increases with age and ex
cess body weight.

19.

The adrenal glands are located adjacent to the kidneys. The adrenal cortex is the outer portion, and the
adrenal medulla is the central portion. The adrenal medulla produces two hormones, epinephrine
(adrenaline) and norepinephrine (nora
drenaline). Both are also neurotransmitters in the nervous system.
Either positive or negative stress stimulates secretion of epinephrine and norepinephrine from the
adrenal medulla. They increase the rate of glycogen breakdown in the liver and skeletal mu
scles,
promote glucose release into the blood by liver cells, and stimulate the release of fatty acids from fat
cells. Epinephrine and norepinephrine also exert profound effects on the cardiovascular and respiratory
systems. They increase heart rate and st
roke volume of the heartbeat and dilate the bronchioles in the
lungs to increase the rate of oxygen delivery to body cells. They also act to shunt blood away from skin,
digestive organs, and kidneys, and increase blood supply to the heart, brain, and skele
tal muscles.
Epinephrine generally has a greater effect on heart and metabolic rates, while the primary role of
norepinephrine is in sustaining blood pressure. Secretion of these hormones by the adrenal medulla is
stimulated by nerve signals carried from t
he brain via the sympathetic division of the autonomic nervous
system. In response to a stressful situation, nerve impulses from the hypothalamus travel to the adrenal
medulla, where they trigger the release of epinephrine. Norepinephrine is released indep
endently.

20.

The two main types hormones secreted by the adrenal cortex in humans are the glucocorticoids and the
mineralocorticoids. Both hormones help maintain homeostasis when stress is experienced over a long
period of time. Glucocorticoids make more glu
cose available as fuel. They act on skeletal muscle,
causing a breakdown of muscle proteins. Glucocorticoids, having an anti
-
inflammatory effect, also
suppress certain components of the body’s immune system. Mineralocorticoids act principally on salt
and w
ater balance. They stimulate cells in the kidneys to reabsorb Na+ and water from filtrate, raising
blood pressure and volume. They also promote the excretion of K+ in the kidneys.

21.

The gonads are the primary source of the sex hormones. The gonads produce an
d secrete three major
categories of steroid hormones: androgens, estrogens, and progestins. All three types are found in males
and females but in different proportions. The testes primarily synthesize androgens, the main one being
testosterone. Androgens p
romote development and maintenance of male sex characteristics. Androgens
produced early in development determine whether a fetus develops as a male or a female. At puberty,
high levels of androgens are responsible for the development of male secondary sex

characteristics,
including male patterns of hair growth, a low voice, and increased muscle mass and bone mass typical of
males. Estrogens, the most important of which is estradiol, are responsible for the development and
maintenance of the female reproduc
tive system and the development of female secondary sex
characteristics. In mammals, progestins, which include progesterone, are involved in promoting uterine
lining growth to support the growth and development of an embryo. Their secretion is controlled b
y
gonadotropins (FSH and LH) from the anterior pituitary gland. FSH and LH production is controlled by
a releasing hormone from the hypothalamus, GnRH (gonadotropin
-
releasing hormone).

22.

Invertebrates produce a variety of hormones in endocrine and neurosecre
tory cells. These hormones
function in reproduction and development. In hydras, one hormone functions in growth and budding
(asexual reproduction) but prevents sexual reproduction. In the mollusc Aplysia, specialized nerve cells
secrete a neurohormone that

stimulates the laying of thousands of eggs and inhibits feeding and
locomotion, activities that interfere with reproduction. Crustaceans have hormones for growth and
reproduction, water balance, and regulation of metabolism. In all arthropods with exoskel
etons, molting
is triggered by a hormone.



Source: www.course
-
notes.org/Biology/Outlines/Chapter_45_Hormones_and_the_Endocrine_System


Jeremy Applebaum and Emilie Doyle
























Chapter 48: Nervous System

An Overview of Nervous Systems:


Tyler, Randy & Hediya

1.

All these animals have some sort of nervous system.

The difference is how the neurons are organized in all these animals.

Hydra
(cnidarians)
-

nerve nets which control contractions and expansions of the gastrovascular cavity

Planarian


small brain and longitudinal nerves cords from a central nervous system

Sea Star


nerve ring connected to radial nerves

Insect
-

brain and nerve
cord

Squid


large brain and image forming eyes

Vertebrate



brain and nerves concentrated in the front of the body. Central nervous system consists of brain
and spinal cord.

2.

The 3 stages of processing information by the nervous system are:
sensory input
,
integration
, and
motor output

3.

Sensory neurons

transmit information from sensors which detect external and internal stimuli

Interneurons

help integrate the signal input

Motor neurons

help with motor output and communicate with effector cells which are musc
le and endocrine
cells

4.

Neurons

are structural and functional units of the nervous system

-
The nucleus

Located in the cell body

-
Dendrites

and
Axons

They are extensions from the cell body

Dendrites

are branched extensions that receives signals from other ne
urons

The Axon

transmits outgoing signals to other neurons and effector cells. They are longer than the dendrites and
there is only one of them per neuron.

Axon Hillock

the region where the axon joins the cell body. It plays the important role of the trans
mission and
integration of nerve signals.

Myelin Sheath

is the insulating later that supports the axon.

Synaptic terminal
are the special endings on the axon. They pass on the signals from neuron to other cells by
releasing neurotransmitters.

Neurotransmit
ters

chemical messages passed on by the synaptic terminal

Synapse


Nature of Nerve Signals:

6.
Membrane potential:

the electrical potential difference across the membrane
-
THINK
-
charges (+,
-
)


Resting potential:

the membrane potential of an unstimulated

neuron

7. It is maintained by unequal distribution of ions across plasma membrane(Sodium and Potassium), the
cytosol being more negatively charged than the extracellular fluid, and the sodium
-
potassium pump
maintaining the differential ion permeabilities.

8. Across the membrane there exists an unequal distribution of ions which results in a charge of
-
70 mV

because the membrane is more permeable to K+ than Na+.

9. The sodium potassium pump maintains the electrical difference across the membrane because it

“pumps”
K+ ions to a high concentration inside of the cell and Na+ ions to a high concentration outside of the cell, thus
creating the charge difference.

10.
Ungated channels

are ion channels in the cell membrane that are always open. Gated channels are i
on
channels that open and close in response to stimuli of stretching, neurotransmitters, and changes in
membrane potential.

11.
Graded potentials

are changes in membrane potential that vary with the strength of the stimulus. They
can either be hyperpolariz
ation(increase in magnitude of membrane potential) or depolarization(decrease in
magnitude of membrane potential.

Action potentials

are an all
-
or
-
none response to a stimuli that are independent of the strength of the
stimulus.

Resting potential

is when no change in the magnitude of the stimuli is taking place, at “rest”.

12. Action potentials are all
-
or
-
none responses which means that only if the stimulus gets to a certain intensity
will the action potential be reached and the cell will fire. Th
ey last only 1
-
2 milliseconds and are produced at
high frequencies.

Voltage
-
gated ion channels are involved in action potentials because these ion channels only open at the
stimulus of an electrical charge. Once open, the K+ and Na+ ions switch places fro
m inside and outside of the
cell respectively.


In this fashion, the cell essentially acts like an assembly line with each worker, or sodium
-
potassium pump
receiving the stimulus from the previous worker, moving its ions(hands) from one side to the other,
and them
passing it off to the next worker.


13. Two factors that underlie the repolarizing phase of action potential are:


1. The sodium channels inactivation gate has enough time to respond to depolarizaion by closing,
returning sodium permeability to it
s low resting level.

2. Potassium channels have time to open and potassium flows rapidly out of the cell during
repolarizaion. This helps restore the internal negativity of the resting neuron.


14. The
refractory period

is the period of time when the neuro
n is insensitive to depolarization; the time
neuron cannot fire (time during which neuron "rechargeable")


15. The action potential is not one signal that travels down the axon , but rather is made up of many little
bursts of action potentials the cause t
he forward, adjacent portion of the axon to depolarize and fire and
continue down the line. When Na+ enters the cell at one point it creates an electrical current that depolarizes
the next region of the membrane (domino effect).


16. The factor that affect
s the speed of the action potential
is the
diameter of the axon. As the diameter increases, the speed
also
increases.

In
vertebrates, most neurons have adopted to be able to send
signals
faster down an axon. This adaptation includes the presence of myelin
sheaths deposited by Schwann cells.
These coatings on an axon allow signals to "skip" down the axon to areas that interact with the extracellular
fluid called nodes of Ranvier. This skipping over portions of the axon due to myelin sheaths is called saltato
ry
conduction. (Saltare means to leap)



17.
Electrical synapses

allow the action potential to spread directly from the one cell to the next. (Connected
by gap junctions). For electrical synapses there is no delay and no loss of signal strengh.

Chemical s
ynapses

are more common. These neurons are
separated by a narrow gap, or synaptic cleft. Their cells are not
electically coupled. Before the action potential can be
transferred, chemical signals must travel across the gap to the
next
neuron.


18. Basically
, electrical signal changes to a chemical signal
(neurotransmitter) which travels across the synaptic cleft from
the
terminal button of one neuron to dendrite of the next, thus
transferring the signal.


19. Binding of neurotransmitters to excitatory
subsides causes
sodium to enter and potassium to leave. Sodium is entering
stronger than potassium is leaving causing the cell to depolarize.

The binding of neurotransmitters to inhibitory synapses causes potassium to rush out of the cell or chloride to
ru
sh in and hyperpolarization occurs, making the cell more negative and even harder to reach the threshold to
produce an action potential.


20.
Summation

is the additive effect of postsynaptic potentials. Several excitatory postsynaptic potentials
(EPSP) act

together to reach a threshold and produce an action potential.


Temporal summation

is when the chemical transmissions from 1 or more synaptic terminals occur
very, close together in time that the membranes voltage has no time to repolarize after the previ
ous
stimulation.

Spatial summation

is when several synaptic terminals from different neurons stimulate the same
postsynaptic cell at the same time and have an additive effect.


21. An
axon hillock

is the average of all the EPSP and IPSP. It shows the level

that the voltage is currently at
and whether it is at the threshold or not so that an action potential can be sent.


22. Neurotransmitters that go through signal
-
transduction pathways take a very long time (a few minutes as
opposed to milliseconds) to dif
fuse to many synapses and moderate activity for mood, attention, and arousal.


23.
Acetylcholine

is a neurotransmitter that can either act as inhibitory or excitatory. It can bind to muscle
cells and depolarize the membrane of the postsynaptic muscle cell
(excitatory) causing a contraction. It might
also biond to heart muscles and activate a signal
-
transduction pathway that reduces strength and rate of
cardiac muscle cell contraction.


Biogenic amines

are derived from amino acids and include epinephrine, no
repinephrine, dopamine, and
serotonin. They affect biochemical processes of postsynaptic cells.


24. The four amino acids and several neuropeptides that work as neurotransmitters respectively are
GABA,
glycine, glutamate, aspartate, and substance P, endorp
hins
. GABA is in the inhibitory synapses in the brain,
while endorphins decrease perception of pain by the central nervous system.


25.
Natural analgestics

decrease perception of pain by the central nervous system.
Endorphins

function as
natural analgestic
s in times of physical or emotional stress such as labor of childbirth.


Vertebrate Nervous Systems:

Central Nervous System (CNS):

consists of the brain and the spinal cord



Responsible for
receiving information from and sends information to the (PNS)

o

Spinal Cord: transmit information from body organs and external stimuli to the brain and send
information from the brain to other areas of the body

o

Brain: control center

Peripheral Nervous System (PNS):

consists of all the nerves outside the CNS



Transmits
information to and from the CNS and regulates the internal environment of an organism



The following nerves are responsible for the sensory ( neurons conveying info to the CNS) and motor ( neurons
that convey signals from the CNS) division of the PNS

o

Crania
l nerves

o

Spinal nerves

o

Associated ganglia

Two Components of the PNS:



Autonomic System

o

Controls involuntary muscles



Sympathetic



Fight or Flight response



Increase heart and
breathing rate



Parasympathetic



Opposes the sympathetic
system




Calms the body



Soma
tic System

o

Controls voluntary muscles; responsible
to external stimuli

Embryonic Development of the Vertebrate Brain



All vertebrate brains develop and diversify from three
embryonic regions: the forebrain, the midbrain, and the
hindbrain



Five brain
regions form by the fifth week of human
embryonic development:

o

The telencephalon and diencephalon develop
from the forebrain.

o

The mesencephalon develops from the midbrain.

o

The metencephalon and myelencephalon develop from the hindbrain.



The adult brainst
em consists of the midbrain (derived from the mesencephalon), the pons (derived from the
metencephalon), and the medulla oblongata (derived from the myelencephalon).

Structures of the Brain:










o

Medulla oblongata:
the base of the brainstem; controls

autonomic functions such as heartbeat and breathing

o

Pons: regulates the breathing centers in the medulla and also helps coordinate movements

o

Cerebellum: center responsible for processing sensory input and coordinating movement output
and balance

o

Midbrain: receives, integrates, and projects sensory information to the forebrain

o

Hypothalamus: it directs the several maintenance activities such as eating, drinking, and body
temperature and also helps govern the endocrine system

o

Thalamus: known as the
brain’s sensory switchboard; it directs messages to the sensory receiving
areas in the cortex

o

Epithalamus: includes the pineal gland and the choroid plexus, one of several clusters of
capillaries that produce cerebrospinal fluid from blood

o

Cerebrum:

cen
ter where sensory information is
analyzed, motor commands are issued, and language is
generated; it is divided into four sections or lobes



Frontal Lobe:

associated with reasoning,
judgment, and problem solving



Parietal Lobe: associated with movement,
orie
ntation, recognition, perception of stimuli



Occipital Lobe: associated with visual processing



Temporal Lobe: associated with perception and
recognition of auditory stimuli, memory, and speech


Left and Right Hemisphere of the Cerebrum:

o

The left hemispher
e specializes in language, math, logic operations, and the processing of serial sequences
of information, and fine visual and auditory details


it specializes in detailed activities required for motor
control

o

The right hemisphere specializes in pattern re
cognition, spatial relationships, nonverbal ideation,
emotional processing, and the parallel processing of information


Language/Speech:



Broca’s area, located in the left hemisphere’s frontal lobe, is responsible for speech production



Wernicke’s area,
located in the right hemisphere’s temporal lobe, is responsible for speech comprehension

o

These areas are also part of a larger network of brain regions involved in language, including the visual
cortex (for reading) and frontal and temporal areas that are
involved in generating verbs to match nouns
and grouping together related words and concepts

Emotions:



The limbic system is associated with emotions such as fear and aggression and drives such as food and sex; it
includes the following structures: hippoca
mpus, amygdala, and the olfactory bulb

o

These structures interact with sensory areas of the neocortex to mediate primary emotions that result in
laughing or crying.

o

The amygdala recognizes the emotional content of facial expression and laying down
emotional memories.



This emotional memory system seems to appear earlier in development than the
system that supports explicit recall of events, which requires the hippocampus (region
involved with memory)

Memory/Learning:



In the frontal lobe, short term

memories are stored, but if those memories want to be retained, they
enter long term memory and are stored in the hippocampus



The transfer of information from short
-
term to long
-
term memory is enhanced by repetition, positive or
negative emotional states
mediated by the amygdala, and the association of the new data with
previously stored information



Motor skills are usually learned by repetition



A form of learning called long
-
term potentiation (LTP) involves an increase in the strength of synaptic
transmis
sion that occurs when presynaptic neurons produce a brief, high
-
frequency series of action
potentials.

o

LTP can last for days or weeks and may be a fundamental process by which memories are stored
or learning takes place.

Bipolar Disorder vs. Major Depress
ive Disorder



Bipolar Disorder: a mood disorder in which the person alternates between depression and the state of
mania



Major Depressive Disorder: a mood disorder, in which a person experiences two or more weeks of
significantly depressed moods, feelings o
f worthlessness, and diminished interest in most activities



Neurotransmitters serotonin and norepinephrine are scarce, activity in the frontal lobe is
slowed, and that stressed
-
related damage to the hippocampus increases the risk of depression, but
there

is an increase amount of norepinephrine during the manic state of the bipolar disorder



Alzheimer’s disease

is a mental deterioration or dementia.

o

It is characterized by confusion, memory loss, and a variety of other symptoms.



Results in characteristic
brain pathology:



Neurons die in huge areas of the brain, often leading to shrinkage of brain
tissue



The diagnostic features are neurofibrillary tangles and senile plaques in the
remaining brain tissue:

-
Neurofibrillary tangles are bundles of degenerated n
euronal and glial
processes

-
Senile plaques are aggregates of ß
-
amyloid, an insoluble peptide that
is cleaved from a membrane protein normally found in neurons

-
Membrane enzymes, called secretases, catalyze the cleavage, causing
ß
-
amyloid to accumulate ou
tside the neurons and aggregate in the
form of plaques



The plaques seem to
trigger the death of the surrounding neurons

Treatments?



Drugs are being developed to prevent the development of senile plaques, which form before overt
symptoms of Alzheimer’s dise
ase develop


Parkinson’s disease



Results from death of neurons in a midbrain nucleus called the
substantia nigra

o

These neurons normally release dopamine from their
synaptic terminals in the basal nuclei

o

Decrease amounts of dopamine



Most scientists
believe that it results from a combination of
environmental and genetic factors




Objectives: Ch 49, Sensory and Motor Mechanisms




Alex and Emily K.

1.

Differentiate between sensation and perception



Cyclical not linear (NOT sensing
-
> brain analysis
-
>
action)

o

Complex, always observing/acting/etc



Sensation: action potentials (nerve impulses) that reach the brain via sensory neurons

o

Action potentials are “all or none”

o

Sensory processes are how information is collected and conveyed to the brain



Perception:

the interpretation of sensations by the brain

o

Ex: color, smell, sounds, tastes

o

Don’t exist outside of the brain (constructions of the brain)

o

Result of sensations

3. Describe the four general functions of receptor cells as they convert energy stimuli into

changes in membrane
potentials and then transmit signals to the central nervous system [LISTED IN ORDER]



Sensory transduction

o

“conversion of stimulus energy into a change in the membrane potential of a receptor cell”



Sensory receptor = change in membrane
permeability, creates “receptor potential” (voltage
gradient on either side of membrane)



Amplification

o

“Strengthening of stimulus energy that is otherwise too weak to be carried into the nervous system”

o

Can occur on edges of sense organ (i.e. sound waves =

20x for inner ear)

o

Can be part of sensory transduction process



Transmission

o

“Conduction of impulses to the central nervous system (CNS)”

o

Sensory receptor (neuron, or receptor)
-
> action potential



Integration

o

Processing of information

o

Signals from sensory
receptors are integrated via graded potentials



Sensory adaptation: decrease in responsiveness during continued stimulation (ex: didn’t sense
the feeling of your shirt until just now; receptors are selective)

o

Note: the sensitivity of receptors is important
in integration, and sensitivity can change (ex: get used to
something and then later need more to feel the same way, like sugar)

4. Distinguish between sensory transduction and receptor potential



See q 3



Receptor potential comes from/during sensory transdu
ction



Process of “sensory transduction” = the gradient in membrane
potential
(receptor potential) which changes the ion flow in pathway
between
receptor and sensory neuron => sending the signal (action
potential)




5. Explain the importance of sensory a
daptation



See q 3



Receptors are selective in what they send to CNS (don’t feel
every heart
beat)

o

CNS isn’t being overwhelmed with a continuous stimulus

6. List the 5 types of sensory receptors and explain the energy
transduced
by each type



Mechanoreceptor: physical/ mechanical energy

o

Pressure, touch, stretch, motion, sound

o

Bend/stretch of plasma membrane of mechanoreceptor cell
-
> increase in permeability to Na and K ions
-
> depolarization
-
> trigger action potentials
-
> transmit to spinal c
ord

o

Ex: muscle spindle, stretch receptor. Hair cell, motion receptor.



Nociceptor: pain

o

Excess heat, pressure, or certain chemicals on skin

o

Naked dendrites on epidermis of skin

o

Very important; keeps us away from harm, stimulates defensive reaction

o

Prostagl
andins sensitize receptors, aspirin/ibuprofen inhibit prostaglandin synthesis




Thermoreceptor: heat/cold

o

Heat/cold

o

Help regulate body temperature (respond to exterior stimuli and body temp)



Chemoreceptor: solute concentration and specific chemicals

o

Gustato
ry receptors: taste (sweet, sour, salty, bitter)

o

Olfactory receptors: smell



Electromagnetic receptor: electromagnetic energy

o

Visible light, electricity, magnetism

o

Photoreceptors: light, in our eyes

7. Explain the role of mechanoreceptors in hearing and bal
ance



Mechanoreceptors used same way in both; hair cells move due to moving fluid/particles
-
> movement creates
receptor potential (voltage gradient)
-
> action potential, sent to CNS



Hearing: see question 10



Balance: see question 10

8. Describe the structure and function of invertebrate statocysts



Statocyst: gravity
-
detector. The invertebrate’s sense of equilibrium.



Common statocyst is made up of

o

Layer of hair cells surrounding chamber with statoliths



Grains of sand or other low densi
ty granules

o

Gravity causes the sand to settle at low pt in chamber,

stimulates hairs in that section



Gives sense of body position, up/down, etc

9. Describe how insects may detect sound



Body hairs that vibrate in response to different sound waves



Tympanic
membrane stretched across internal air chamber (AKA eardrum)



Vibrations in membrane stimulate receptor cells attached to inside of membrane



Receptor cells send nerve impulses to brain

10. Refer to a diagram of the human ear and give the function of each st
ructure



HEARING:



Outer ear: funnels in sound

o

pinna

and the ear canal: deliver the sound waves to the middle ear. Wax and hair in pinna/ear canal
keep out dust/insects/etc

o

eardrum

(tympanic membrane): vibrates according to the frequency/amplitude of sound waves that hit
it



middle ear: transmits and amplifies or dampens sounds from ear drum

o

Round window:

flexible membrane located opposite the oval window in cochlea. Keeps cochlear f
luids
in cochlea and multiples sound waves generated from the oval window membrane.

o

The ossicles: transfer sound waves to mechanical motion



Malleus: hammer. Eardrum
-
> malleus
-
> incus




Incus: anvil. Malleus
-
> incus
-
> stapes




Stapes: stirrup. Vibrations
of ear drum lead to movements of Stapes.

o


semicircular canals: maintain person’s balance by responding to gravity and the acceleration changes of
head




Inner ear: interprets sound, sends to brain

o

The
cochlea
: the main hearing organ. Filled with endolymph
and perilymph fluid. Movement of stapes
-
>
pressure waves within cochlea.



Organ of Corti: in center duct of cochlea, surrounded by endolymph fluid, sits on basilar
membrane. has hair cells and nerve receptors that send signals to brain



Basilar membrane: f
loor of cochlear duct



BALANCE:



Vestibular system (in inner ear)



the utricle: sensitive to body position and linear motion




saccule: sensitive to up/down movements



3 semicircular canals: X, Y, and Z axis. In base of each canal is a cluster of hairs topped b
y a dollop of endolymph
(gel stuff) (hairs and endolymph = cupula).

o

Body motion
-
> movement of endolymph
-
> hairs bend
-
> action potentials/nerve signals sent to brain in
proportion to change in body motion (AKA hairs adjust very quickly to maintain equili
brium)

o

If constant body rotation (spinning), mechanism adjusts. When spinning stops, fluid still moves and we
feel dizzy











11. Explain how the mammalian ear functions as a hearing organ



More detail: see question 10



Tympanic membrane transmits sound waves to ossicles (malleus, incus, stapes)



Ossicles transmit mechanical motion through oval window to fluid in cochlea



Pressure waves bend receptor hairs in Basilar membrane and organ of Corti



Bending of hair cells trigger

action potentials in auditory nerve; send “sound” to brain



* basilar membrane regions vibrate more at different frequencies
-
> detect different pitches

12. Explain how the mammalian ear functions to maintain body balance and equilibrium



More detail: see q
uestion 10



Utricle, saccule, and semicircular canals contain hair cells that detect body position and motion



Endolymph fluid in semicircular canals flows as body moves, bends hair cells in utricle, saccule, and semicircular
canals



Bending of hairs “increas
es the frequency of action potentials in the sensory neurons in direct proportion to the
amount of rotational acceleration”

13. Describe the hearing and equilibrium systems of nonmammalian vertebrates



Hearing:

o

no ear drum or cochlea, but have utricle,
saccule, semicircular canals

o

vibrations of water from sound waves are conducted thru skeleton and/or the air
-
filled swim bladder
-
>
inner ears



balance:

o

lateral line system (see diagram)



water flows through tube and stimulates neuromasts (mechanoreceptors) a
long the way



neuromasts: have hairs under gelatinous cap (cupula)



motion
-
> movement of gel
-
> bend hairs
-
> energy transduced into receptor potentials
-
>
transmitted along nerve to brain

o

only works in water

o

terrestrial organisms: stapes in middle ear tra
nsduces sound vibrations to brain

14. Explain how the chemoreceptors involved with taste function in insects and humans



taste and smell interrelated



Insects: taste with their feet.

o

Sensillae: sensory hairs on feet and mouthparts that function as taste rec
eptors

o

Tasting hair has several chemoreceptor cells, each responsive to certain chemical (sugar, salt)

o

Olfactory sensillae: sensillae located on antennae, used for smelling airborne chemicals



Humans: taste & smell: molecule must dissolve in solvent to reac
h receptor + trigger sensation

o

Taste:



Taste buds: modified epithelial cells



Papillae: projections on tongue associated with taste buds



5 “tastes”: sour, sweet, salty, bitter, umami (savory)



Each receptor cell is more response to particular chemical, brain

integrates the different
responses to perceive complex flavor

o

Smell:



Olfactory neurons line upper portion of nasal cavity and send impulses along their axons to
olfactory bulb (in brain)



Cilia of the olfactory neuron receptor cells extend into mucus layer

that coats nasal cavity



Odorant binds to receptor molecules on cilia’s plasma membrane, leads to action potentials sent
to brain

15. Describe what happens after an odorant binds to an odorant receptor on the plasma membrane of the olfactory cilia



Odorant
binds to receptor molecules on plasma membrane of olfactory cilia (which connect to neurons)



Triggers signal
-
transduction pathway

o

G
-
protein
-
signaling pathway, adenylyl cyclase, cyclic AMP

o

Cyclic AMP opens NA
+

channels in olfactory receptor membrane



Depolarizes membrane



Generate action potential



Action potential
-
> brain

16. Explain the basis of the sensory discrimination of human smell



Can sense thousands of different odors



Not as good as some other animals

not needed for mating (i.e. moths), detecti
ng territory (i.e. cats) or
navigation (i.e. salmon), or “conversation” (i.e. ants)



Still important for taste and smell; much of smell is actually taste



Taste and smell interrelated

17. compare the structures of, and processing of light by, the eye cups of

Planaria, the compound eye of insects, and the
single
-
lens eyes of mollusks



Eye cup (Planaria)

o

2 eye cups, facing Front
-
right and front
-
left

o

Photoreceptors in each eye cup respond to light stimulus coming from both directs

o

Planaria

will turn head so that light coming into each eye (and therefore causing nerve signals to be sent
to brain) to be minimal

o

This response helps hide from predators (keeps Planaria in dark areas)



Compound eye (insects)

o

Thousands of ommatidia with a lens on e
ach one

o

Cornea and crystalline cone under/on lens focus light into rhabdum (pigment plates) , rhabdum sends
the light to receptor cells

o

Image created by different light intensities entering from different ommatidias



Single
-
lens eye (mollusks)

o

Very similar

to mammalian eye (convergent evolution)

o

Cephalopod eye (most complex mollusk eye)

o

Vertebrate eyes are nerve cells then sensory cells (underneath, toward brain)

o

Mollusks are sensory cells (pointing outward) then nerve cells


18. Refer to a diagram of the v
ertebrate eye to identify and give the function of each structure.


Sclera
-
the white part of the eye, thick fleshy covering, protects inside organs of the eye

Cornea
-
transparent covering over the front of the eye, continues with the sclera

Iris
-
pigment s
urrounding the pupil, controls light intensity by dilation and constriction

Pupil
-
opening in iris that allows light to pass threw into the eye

Aqueous Humor
-
fluid found between the cornea and lens, helps keep the eye round in shape

Lens
-
transparent mini
-
ma
gnified glass focuses light coming into the eye on the back of the eye

Suspensory Ligament
-
hold lens in place, change lens shape

Vitreous Humor
-
like
-
gel fluid found between the lens and the back of the eye, helps keep the eye round in shape

Optic Disk (bli
nd spot)
-
Where the retina becomes the optic nerve, no light receipting cells, light that hits this area is
unable to be seen.

Optic Nerve
-
carries the nerve impulse from the retina to the brain to be processed


Fovea
-
Area on the retina where the center of the visual field appears

Retina
-
light sensitive receptors on the inner eye, continuous with optic nerve

Choroid
-
provides body supple to the eye

Central Artery and Vein
-
brings in the blood supply to the choroid

Ciliary Body
-
helps hold lens in place and produces the liquid to fill the aqueous humor


19. Describe the functions of the rod cells and the cone cells of the vertebrate eye.


Rod Cells
-
more sensitive to light, can not see color, make it easier to see at
night, only black and white vision

Cone Cells
-
less sensitive to light, can see color, not help with night vision, distinguish colors in daylight



20. Explain how the retina assists the cerebral cortex in the processing of visual information.


The retina c
overs pretty much the entire inside of the eye making a point
-
by
-
point visual field. As each nerve reacts
from the presences of light that hits it, it sends a message to the brain. So that messages do not get mixed each nerve
has its own path to the brai
n. The brain must process all this information to produce the image we see.


21. Describe the three functions of a skeleton.


Protect the body’s important organs.

Support the body. Without a skeleton we would a blob of tissue on the ground.

Movement of li
mbs to complete daily tasks and move to a new area.


22. Describe the hydrostatic skeleton functions and explain why they are not found in large terrestrial organisms.


The hydrostatic skeleton uses fluid to help an organism keep its shape. The fluid is h
eld in pressurized closed body
compartments. Nematodes, flatworms, annelids, and cnidarians all have this type of skeleton. They will use muscles to
change the shape of their fluid compartments to move. This type of skeleton cannot hold the weight that
a bone
skeleton can. It is unable to support the body when it is up off ground as it would be during walking and running.


23. Distinguish between an exoskeleton and an endoskeleton.


Exoskeleton
-
a skeleton which is found on the outside of the body, as
the body grows its skeleton will grow with it, either
by adding layers or sheading and growing a new one.


Ex: Insects, clams, lobsters, mollusks

Endoskeleton
-
a skeleton which is found on the inside of the body, will grow as the body grows, not always made

of bone


Ex: sponges, mammals, birds, reptiles, most animals



24. Explain how the structure of the arthropod exoskeleton provides both strength and flexibility.


Depending on the thickness of the exoskeleton will determine strength and flexibility. In t
hinner areas, like the joints, it
will be very flexible. In thinker areas in will be stronger in strength and found in areas to protect vital organs.


25. Explain how a skeleton combines with an antagonistic muscle arrangement to provide a mechanism for m
ovement.


Antagonistic muscles will work against each other. For example in the upper arm the biceps is antagonistic to the triceps.
The biceps works to flex the elbow and the triceps work to extend the elbow. Together they create a full range of
motion.




26. Using a diagram, identify the components of a skeletal muscle cell.






Muscle Fiber
-
one singles muscle cell, many make up a muscle

Myofibril
-
smaller fiber within a muscle fiber, contain thin and thick filaments

Sa
rcomere
-
one contractile unit of fiber

Thin Filament
-
actin strand of protein

Z Line
-
separates the sarcomeres

I Band
-
Only thin filament is seen

A Band (H Band is photo)
-
Only thick filament is seen



27. Explain the sliding
-
filament model of muscle
contraction.


The thin and thick filament will not change length. The thick filament will attach onto the thin filament moving it closer
together, shortening the gap between the thin filaments. Contracted muscle will have thin filaments closer together
t
hen a relaxed muscle.


28. Explain how muscle contraction is controlled.


The attachment sites on the thin filaments are covered by tropomyosin and troponin complex. This inhibits the thick
filament from attaching onto the thin filament. When a nerve imp
ulse reaches the muscle it releases calcium ions.
These ions will bind to the tropomyosin and troponin complex to revile the attachment sites. Now the thick filament can
now attach to the thin filament and contract the muscle.


29. Explain how the nervous

system produces graded contractions of whole muscles.


If a muscle continues to receive an impulse from the nerve before that last impulse is over the muscle will contract for
longer. If only one impulse is sent it results in a twitch. Many is a row wit
hout a brake results in one smooth full muscle
contraction. It may also depend on how many muscle cells are attached to a nerve. If many are attached to one nerve
then all the muscle cells will move together as one producing movement.


30. Explain adapti
ve advantages of slow and fast muscle fibers.


Bundle of Muscle Fibers

Slow muscle fibers help maintain posture. They have help organisms evolve into today’s humans. Without these muscle
fibers we would not be able to stand up how we do today.

Fast muscle fibers take part in sh
ort, rapid, powerful contractions. This will help in running from predators. Any quick
movement needed to survive will come from fast muscle fibers.


31. Distinguish among skeletal muscle, cardiac muscle and smooth muscle.


Skeletal muscles play a role i
n movement, posture and protection of organs.

Cardiac muscles will only be found in the heart! They have special intercalated discs to help direct electric impulses to
contract the heart as one.

Smooth muscles are found along the walls of organs to help m
ove stuff through the body. For example food through
the intestines, or blood through blood vessels. They are not as defined as skeletal muscles.



32. List the advantages and disadvantages associated with moving through:


An aquatic environment


A
terrestrial environment


Air


Aquatic
-
Organisms who swim do not have to deal with the act of gravity on them. However they have to deal with a lot
more resistances since water is denser then air.


Terrestrial
-
Organisms who run, walk, hop, or craw will h
ave to deal with the force of gravity pushing down on them.
However since air has a very low density is it much easier to move through. Moving on land provides many more way to
move then the water does.


Air
-
Gravity is a major problem for all flying anim
als. Since they are higher in the air they will have a great force trying to
pull them back down to earth. But the air is for sure lest resistant then the water.