hemoglobin and altitude

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what happens at high altitude? I know that bpg shifts the curve the to the right at high altitude but I read in a practice test that high altitude animals need higher oxygen affinity and thus the curve is shifted to the left. Anyone can explain it better?

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Yes, higher affinity is needed because the partial pressure of oxygen in the air is lower at high altitudes. Not sure how this is accomplished, though I do know the % hemocrit in blood increases substantially after some time up high.

That's all I got. I was living at 4000 meters for the last little while, I probably should have learned more.
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there are alot of things that occur when at hight altitudes, however some mechanisms take longer to occur than others

the first thing that happens is an increase in breathing rate to compensate for the lack of oxygen at that altitudue

im not sure when the affinity of hemoglobin, left shift of curve, changes but it is not immediate, and usually takes some time

Evntually, i think like one-two weeks at high altitude, erythropoetin (spelling?) will be released causing an increase in Red Blood Cells and ultimately increasing hemoglobin concentration in the blood. there are some other things that occur inbetween but i cant think of them off the top of my head, but this is more than what you will need to know on the test.
 
yeah well gleek, they are all unclear about what happens so i'm asking again.

i am 100% positive that it is at least sometimes a right shift, because in biochem and animal physiology they told us that bpg increases with altitude and thus obviously it would be a right shift. But I have seen places that mention a left shift in a little bit different situation, I jsut want to find out what people have to say.
 
yeah well gleek, they are all unclear about what happens so i'm asking again.

I'm sorry to hear that. I wasn't trying to be rude, I only wanted to point out that this had been discussed recently.

The reason that the hemoglobin experiences a left shift at the lungs is due to the decreased pO2 of the inspired air. You are right when you talk about BPG causing a right shift.

Something that must be considered though is where you are talking about when you speak of a right or left shift. BPG does have an effect, but it's at the tissue. You want a right shift at the tissues because you want the tissues to get oxygen.
 
I think I've raised this question before, but is it really possible for the curve to shift left at the lungs and right at the tissues simultaneously? The curve as it's usually presented doesn't usually mention locaation, and questions typically ask how the curve shifts overall, so I thought that all the Hg in your blood has a certain affinity at a given time. Otherwise, just stating "how the curve shifts" is pretty meaningless/impossible, which I gather is your point...
 
I appreciate what you are saying. In reality, changing only one condition will likely cause only a left or a right shift. Where the confusion comes in is when more than one condition is changing at the same time.

The problem with asking a question like "what happens at high altitude" is that many things change over a period of time. Are people asking about the immediate effects of the change in pO2, or to the response of the body after some period of time?

When I talk about examining the environment in which the hemoglobin is in, I am trying to show that something like 'high altitude' can have complex effects and a generic answer may not be possible.

I think the problem with these "high altitude" threads is not that people don't understand the physiology, but that the questions are not specific enough.

EDIT: I should also mention, though, that it definitely is possible to have a left shift at the lungs and a right shift at the tissues at the same time. In fact, that is the way it is supposed to work. The differing conditions of the lungs and the tissues is what causes the left and right shift (which can also be looked at as increased or decreased affinity for oxygen). If this were not the case, all the hemoglobin in the body would have the same affinity for oxygen, which would decrease oxygen transport.
 
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Ok Guys so there is actually a whole passage in Kaplan full lenth 4, that deals with acclimitization to high altitude and here is exaclty what it says in the passage:

Acclimitization to alltitude occurs in a number of ways:

1) The body immediately responds by increasing ventilation to around 65% above normal. This increase leads to the exhalation of CO2 and and in increase in blood pH which tends to inhibit the respiratory center and oppose the stimulatory effect of decreased pO2. Over a period of 2-5 days, this inhibition declines and ventilation can increase upto five times normal.

2) After about two weeks at high alltitudes, the concentration of erythrocytes increases. Consequently, hemoglobin concentration in the blood increases as well.

3) At the time of exposure to low atmospheric pressure, the body increases cardiac output. The cardiac output falls back to normal after about 2 weeks. Over time, there is an increase in the capillarity of the tissues.

4) In humans native to high alltitudes, mitochondria and oxidative enzymes are more plentiful than in humans born at sea level. This cellular acclimatization allows more efficient oxygen utilization
 
There's a lot of good info in this thread, but a lot of it doesn't pertain to the actual question asked:

will the Hb disassociation curve shift to the right or the left?

I'll give you guys enough info to find/google the answer yourself with a bit of thinking:

1) What happens to breathing rate at higher altitudes? Does it increase (hyperventilation) or decrease (hpoventilation)?
2) How does this affect PCO2 levels?
3) How does PCO2 levels affect H+ levels? (Think carbonic anhydrase!)
4) Remembering what you know about the Bohr and Haldane effect on Hb disassociation, how does H+ and PCO2 levels affect the oxygen disassociation of Hb?

While you can try to rationalize what you think would better, either muscle offloading or higher affinity in the lungs, its not really that meaningful if you can't think of the mechanism "Why?". The four questions I've asked are all answered via google (or even SDN search!) and should lead you to your answer. GL!
 
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well i said that, it is a left shift by what you're saying but the bpg will cause a right shift. but i think i understand the actual changes now, my biochem book had a section and it makes a lot more sense.
 
well i said that, it is a left shift by what you're saying but the bpg will cause a right shift. but i think i understand the actual changes now, my biochem book had a section and it makes a lot more sense.

That's good.
I believe the 2,3DPG effect is a slightly longer term effect. That's a good point though, you would have to consider this situation in terms of acute or chronic
 
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