What are the things that happen to your body at high altitude
->name the two
1) Increase in breathing
2) Increase in hemoglobin and red blood cell mass
What are the negative consequences of high altitude
- blood pressure becomes higher
- pressure in the lungs becomes higher
- initially very prone to all aspects of altitude illness
Is Acute Mountain Sickness common in people who go to trek up to high altitudes
- yes
- > pretty much a really bad hangover
- > headaches, nausea, vomiting, dizziness and milder symptoms come with it
What is plasma
- the liquid component of our blood
- > delivers oxygen to our tissues
- > only 3%
-the rest is delivered by hemoglobin
What is air comprised of
-78% nitrogen and 21% oxygen
What is respiration
- how oxygen is transported from the air into our tissues
- in humans, the respiratory system consist of our lungs and a series of connected tubes that transfer air to and from the lungs
How does the movement of oxygen and other gases between the alveoli and the bloodstream occur
- it occurs through diffusion
- >gasses move from an area of high concentration to low concentration
What are the two factors that determine the rate at which oxygen diffuses into the blood
- it depends on surface area of the tissue across which diffusion occurs
- and also the concentration gradient
-larger surface area or steeper concentration gradient will increase the rate of diffusion
Why does decreased atmospheric pressure reduce our ability to uptake oxygen?
- at increased altitudes, the atmospheric pressure is decreased
- partial pressure of oxygen in the venous blood returning to or entering the lungs is similar both at sea level and higher altitudes
- > this means that the concentration gradient of oxygen between the lungs and the blood is reduced at higher altitudes
What is hypoxia
-tissues deprived of oxygen
What is acclimatization
- physiological responses in our bodies to help us adjust to low levels of oxygen
- > some physiological responses to hypoxia kick in immediately, while other responses occuring more slowly
What is the tidal volume
- the amount of air that is moved in and out of the lungs in each breath
- > average tidal volume is 500 milliliters
- > only about 350 milliliters reaches the alveoli to deliver oxygen into the bloodstream
- > the other 150 milliiters is called dead space because it remains in the airway where gas exchange does not occur
What is the primary response to hypoxia
- increasing tidal volume
- > once this limit is reached, the only way to further increase oxygen uptake is to increase our breathing rate
-in addition to breathing faster and more deeply, increased heart rate is a relatively rapid response to low oxygen conditions
Does work reduce at higher altitudes
- yes
- > the capacity to perform work at high altitudes may be suppressed even more in individuals who have breathing conditions such as asthma
- > asthma can limit how much they can increasing their breathing rate or tidal volume
What is Acute Mountain Sickness
- one in four people who travel to altitudes higher than 2500 meters experience this illness
- > the most common symptom is a headache
- > can also be accompanied by fatigue, loss of appetite, nausea, dizziness, vomiting, egc
- > these symptoms usually begin a few hours after ascent
Does physical fitness and age determine if you get acute mountain sickness
- no
- > it is remarkably hard to predict who will be affected by AMS
- > it appears that some people are more inherently susceptible
- the likelihood that you’ll be affected by AMS increases with your rate of ascent
- > faster ascent means the body has less time to acclimate
- also, climbing to higher altitudes increases the likelihood of AMS
- > because oxygen deprivation is more severe and acclimatization is less likely
- vigorous exercise also increases the likelihood of AMS
- > because higher levels of physical activity requires higher levels of oxygen intake
Is there a drug that prevents and treats AMS
- yes
- > acetazolamide
- > it speeds up the breathing rate so it is useful for sleeping
- but it does not mast the symptoms of AMS
- > there are also side effects like tingling sensations or pins/needles in your feet and hands
- > also a greater tendency sunburn easily and can contribute to dehydration
If AMS symptoms are severe, what else can it lead to
- it can lead to high altitude cerebral edema
- or high altitude pulmonary edema
- in hace, the fluid accumulates in the lungs while with hape, the fluid accumulates in the lungs
- > both can be life threatening as fluid leaks from blood vessels into the tissues
- HAPe can progress rapidly and is often fatal when fluid collects in the lungs
- > it interferes with the diffusion of oxygen into the blood
- > causing oxygen levels in the blood to plummet further into a downward spiral
How do 140 million people live in altitudes above 2500 meters
- they have genetic adaptations or physiological traits
- > these traits enhance their ability to cope with low oxygen environments
- > often times these individuals do not exhibit Acute Mountain Sickness
What are the adaptations of people whose ancestors permanently have lived at high altitudes
- increased lung volume
- > barrel-chested appearance
- ability to carry more oxygen on each red blood cells
- increased blood vessel diameter
- faster and deeper breathing
What does an enlarged lung capacity result in for native highlanders
- increases their tidal volume
- > increases the total amount of air that they can inhale with each breath
- efficiency of oxygen exchange is increased
- > because lower proportion of inhaled air enters the dead space
- increased lung volumes are also associated with an increase in the surface area of the alveoli
- > this increases the oxygen diffusion into the blood
Give an example of reversible acclimatization
- Andean highlanders have developed an ability to carry more oxygen due to an increased number of red blood cells
- > this is not a permanent adaptation
- > after spending several weeks at low altitudes, their hemoglobin levels drop
- > this is an example of reversible acclimatization
How do Tibetans survive at high alttiudes if they have red blood cells and hemoglobin concentrations similar to that of lowlanders
- they breathe faster and more deeply
- > they also have increased blood vessel diameter which allows for greater circulation of red blood cells and enhanced oxygen transport
How are Ethiopian highlands able to survivde
- they have Endothelin receptor type-B
- > this is associated with high altitude adaptation
- > it improves cardiac tolerance to hypoxia in Ethiopian Highlanders
