Grade 8 Science: Cryogenics Article and Questions

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Nov 15, 2013 (3 years and 11 months ago)

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Grade 8 Science
: Cryogenics Article and Questions


Cryogenics is a branch of physics concerned with very low temperatures: how to produce
the lowest temperatures possible (below minus 30oC), and what effects these low
temperatures have on organisms or mat
erials. The prefix cryo is derived from the Greek
word kryos, meaning "cold." The person considered by most to be the originator of
modern experimental science, Francis Bacon, died as a result of a spontaneous
experiment he was conducting on the effects of

low temperatures. In 1623, while
traveling on a cold and snowy day, Bacon decided to "experiment" to see whether snow
would delay the putrefaction of flesh. He stuffed a fowl with snow to observe the effects.
In the process, he caught a sudden chill. Over

the years, this turned into acute bronchitis,
which contributed to his death in 1626. Although some animals are able to lower their
body temperatures during
hibernation
, most animals, like people, cannot tolerate
freezing temperatures within their body t
issues. Normally, when an organism is exposed
to below
-
freezing temperatures, ice forms in smaller blood vessels and either bursts the
blood vessels or stretches them beyond the point where they can function normally. In
addition, ice in the blood vessels
"captures" the water content, making it impossible for
the blood cells to survive. Other types of cells are also damaged during freezing. Frostbite
is a common malady caused by cold temperatures; frozen skin and blood cells are
damaged from the dehydration

due to freezing. Scientists have discovered, however, that
some varieties of frogs and turtles can actually survive being frozen. When these animals
sense ice on the outsides of their bodies, their livers produce extra glucose (blood sugar),
which floods
into their cells to protect the cell from freezing and from damage. This also
holds the cell's shape so it doesn't collapse upon itself. Nucleating proteins "guide" water
out of the cells, allowing the water to go in between the cells and the organs. This
allows
the water to freeze, but in small pieces, without "spears" that could puncture the cell
membrane. Scientists know of only one mammal, the Arctic ground squirrel, that seems
to be able to tolerate ice crystals in its bloodstream during a physiologica
l state that falls
somewhere between hibernation and freezing. Scientists are studying the
"cryoprotectants" of these animals to see whether they have application for the freezing
of human organs for transplants. So far they have been successful in freezin
g only single
cells (e.g., sperm cells) and corneas for transplants.


Answer the following questions on a separate sheet of paper and pass in:


1.

What branch of science does cryogenics come from?

2.

Where do we get the work cryogenics from?

3.

Who is the first to
try this experimental science?

4.

What is hibernation?

5.

How does frostbite occur?

6.

How do some varieties of frogs and turtles survive being frozen?

7.

What type of proteins guide water out of cells?

8.

What is the only known mammal to use a form of cryogenics?

9.

Why wo
uld cryoprotectants help humans?

10.

What are the only human cells that have been successfully frozen so far?