Week
8 Blog Post
1) Select
only ONE of the following
environmental stresses: (a) heat, (b) high levels of solar radiation, (c)
cold, or (d) high altitude. Discuss specifically how this environmental stress
negatively impacts the survival of humans by disturbing homeostasis.
The environmental stress I chose is (d) high
altitude.
While there are two different kinds of altitude
changes with hot days/cold nights, strong winds/humidity low and low air
pressure, I am focusing on the low air pressure that happens in higher mountain
regions.
While the oxygen level at an altitude of 2
miles is the same than at sea level, the air pressure drops by 30%. This causes the body to not be able to have
oxygen enter the vascular system as easily as it did at sea level. As a result,
the person will feel fatigue, and at high altitude may have a loss of appetite,
vomiting, headaches, which are symptoms of hypoxia (oxygen deprivation). The
body tries to counter with a physiological response by increasing the
breathing, but that can cause heart failure.
Prolonged hypoxia will eventually lead to the
death of the person, unless oxygen is provided.
2) Identify 4 ways in which humans have adapted
to this stress, choosing one specific adaptation
from each of the different types of adaptations listed above (short term,
facultative, developmental and cultural. Include images of adaptation.
In regards to high altitude the short term
adaptation or initial physiological response for an individual that is new to
high altitude would be increase in ventilation (breathing faster and deeper),
which causes an increase in the heart rate as well as an increase in blood
pressure.Another way is to slow down activities and rest
to not put the body under more stress.
This adaptation will change as soon as the environmental stress is removed.
Increased heart rate and blood pressure by breathing faster
The facultative adaptation to high altitude would
be that the body acclimatizes to the environment. It would do so by producing
more red blood cells that help carry more oxygen throughout the body. Bringing more blood throughout the body will help with the fatigue and headaches. The lungs
increase to allow the osmosis of oxygen and carbon monoxide to take place. This adaptation is only going to go away once the environmental stress is removed, however it takes longer than the actual short term adaptation to vanish.
One developmental adaptation to high altitude would be the increased production of hemoglobin to help carry increased oxygen levels that can be carried by the blood. This adaptation was observed in people living in the Andes of Bolivia and Peru and the population has lived there for over 2,000 years.
Aymara Woman in Peru Mountain
Another developmental adaptation would be the
change of the DNA of a population, such as increasing the size of the heart and
lungs. This happened to the people of Tibet and Nepal, both of whom are living in
the Asian Himalayas for generations. This happened, because the population
adapted by breathing faster, yet not increasing their hemoglobin levels. The
DNA test of a man from Tibet showed that he had 10 more oxygen processing genes
that a person living at sea level. Those genes will be passed on to his
offspring, as it is very beneficial for the climate he lives in.
Image of a man in Tibet
The cultural adaptation to high altitude and low
air pressure is the use of oxygen masks. They are used by mountain climbers
that otherwise would (usually) not reach the top of a mountain alive. I say
usually, because I remember that mountain climber Reinhold Messner and Peter Haberle, climbed Mount Everest in 1978 without the help of any oxygen tanks.
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3. What are the benefits of studying human
variations from this perspective across environmental clines? Can information
from explorations like this be useful to help us in any way? Offer one example
how this information can be used in a productive way.
The benefits of studying human variations is to
find out what we can and cannot do under certain environmental conditions.
Having this knowledge prevents people from entering regions that they might not
be suited for or need equipment for. It also helps people that might get altitude
sickness to use all kinds of remedies to adjust to the low air pressure.
The Olympic Teams of the United States has a
training facility in Colorado that uses the physiological benefits, such as
producing more hemoglobin, during competition. The effects wear of within a few
weeks, so studying the human variation helped to determine how long they should
stay in the camp and when they should leave it to enter the competition.
4. How would you use race to understand the
variation of the adaptation listed in #2? Explain why the study of
environmental influences on adaptation is a better way to understand human
variation than by the use of race.
A race of a population does not influence the
adaptations to high altitude conditions and low air pressure, which is the environmental
stress I chose. Race plays a part in the adaptation to high levels of solar radiation,
e.g. white and African American.
It is better to study the environmental influences
on adaptation rather than the use of race to understand the human variation, because
not all of them, such as my choice, are influenced by race.
