| MadSci Network: Medicine |
Dear Ashutosh,
Thank you for your question about hypothermia. First I will define
hypothermia for you, then explain how temperature affects proteins, and
finally describe how failing proteins in the heart lead to the majority of
deaths in hypothermic patients.
What is hypothermia? Hypothermia is a decrease in the temperature
of the center of your body. Your skin is designed to withstand changes in
temperature, but your central organs, such as your kidneys, heart, and
brain can not tolerate much change. There are different levels of
hypothermia. As Scott Dietert described in his MAD Scientist essay
entitled Hypot
hermia and death, "this condition is often graded as mild (body
temperature=34-35*C), moderate (30- 34*C), and severe (<30*C) based upon
the measured body temperature." The colder a person gets, the more likely
they are to die from the cold.
Why does cold harm your body? Throughout your body there are
proteins. Proteins do most of the work in your body, like tiny,
microscopic machines. If proteins break, they must be replaced, or your
cells will start to malfunction. Proteins are very sensitive to the
cold. All but a few proteins in your body work best at 98.6F/37C
degrees. As they become colder (or warmer) the proteins become less
effective in doing their jobs. Finally, they are so ineffective that your
vital organs fail. Your heart proteins stop beating, your lung proteins
stop breathing, and your brain proteins stop thinking.
What do hypothermic patients die from? Most deaths from
hypothermia are suspected to be from heart failure. It seems that your
heart proteins are most sensitive to the effects of hypothermia. One way
in which this can happen is the fatally rapid re-warming of a patient with
hypothermia. In people that become too cold, the blood stops circulating
to the arms and legs. This helps keep warmth in the core of your body.
If warmed too quickly, the blood vessels will open, sending the cold blood
from the arms and legs straight back to the heart. This cold blood will
cause the proteins to malfunction, and the heart will fail. Without a
heartbeat, a person can't live for too long. (Although it is true that a
cold person without a heart beat can live longer than a warm person
without a heart beat.)
Do you want to know more about hypothermia? I recommend reading
information from one of the experts on outdoor survival, the Search and Rescue Society.
The function of our bodies is very interesting. If you want to know more
about proteins that work at different temperatures, about failure of the
heart, or about anything else, please ask us another question!
Sincerely,
John Carlson
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