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Old 04-24-2012
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RBC Carboxyhemoglobin Dissociation Curve!

Carboxyhemoglobin is a form of Hb that is bound to CO instead of o2, right?
Then why does it cause a left shift in the dissociation curve?!

In other words, could someone plz explain the whole carboxyhemoglobin thing :S

Thnx in advance!

Last edited by Renaissance; 04-24-2012 at 09:04 AM.
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Carboxyhemoglobin - when CO binds to Hb at one of the four sites on Hb. When it is bound to this one site, it increases the Hemoglobins affinity for O2 on the other three sites. This increased affinity increases blood O2 content but none of it is released as the O2 and hemoglobin are tightly bound. This leads to a left shift and less delivery of O2 to tissues causing hypoxic injury.
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ok so an increased affinity of CO to Hb causes it to be the favored one to bind first, after that the remaining sites bind tightly to o2 and dont let go!

yes, i see know.
Awesome! Thnx man

Just a minor correction, all the Hb modification diseases cause a decrease in blood o2 content (due to decreased Hb saturation)
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Quote:
Originally Posted by Renaissance View Post
ok so an increased affinity of CO to Hb causes it to be the favored one to bind first, after that the remaining sites bind tightly to o2 and dont let go!

yes, i see know.
Awesome! Thnx man

Just a minor correction, all the Hb modification diseases cause a decrease in blood o2 content (due to decreased Hb saturation)
No problem.

Here's what I found: http://en.wikipedia.org/wiki/Carbon_...ing#Hemoglobin

"Because of the increased affinity between hemoglobin and oxygen during carbon monoxide poisoning, the blood oxygen content is increased. But because all the oxygen stays in the hemoglobin, none is delivered to the tissues"

PaO2 depends on O2 on HB and O2 dissolved in Plasma but majority of the contribution is from O2 bound to Hemoglobin. I think the O2 content increases because Hb is more saturated with O2 and doesn't let go off it (hence you get the cherry red color).

I am not sure though .. That's just my understanding from it.
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Quote:
Originally Posted by Hope2Pass View Post
No problem.

Here's what I found: http://en.wikipedia.org/wiki/Carbon_...ing#Hemoglobin

"Because of the increased affinity between hemoglobin and oxygen during carbon monoxide poisoning, the blood oxygen content is increased. But because all the oxygen stays in the hemoglobin, none is delivered to the tissues"

PaO2 depends on O2 on HB and O2 dissolved in Plasma but majority of the contribution is from O2 bound to Hemoglobin. I think the O2 content increases because Hb is more saturated with O2 and doesn't let go off it (hence you get the cherry red color).

I am not sure though .. That's just my understanding from it.
Ur right, it makes sense.
It says decreased o2 content in FA! which one is correct?
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All that increases affinity will move dissociation curve to the left:

HbF, CO, MtHB.

Alkalosis will also left shift.
But interestingly, alkalosis turns on the part of the glycolytic pathway to produce more 2,3-DPG and 2,3-DPG will right shift. (I like this part)
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Quote:
Originally Posted by Renaissance View Post
Ur right, it makes sense.
It says decreased o2 content in FA! which one is correct?
In CO poisoning - CO binds Hb decreasing O2 saturation but increases affinity for those O2 molecules that are already bound to Hb
So it shifts curve to left and decreases o2 sat.

O2 content decreases as a result of decrease in saturation
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Quote:
Originally Posted by MedicalExaminer View Post
In CO poisoning - CO binds Hb decreasing O2 saturation but increases affinity for those O2 molecules that are already bound to Hb
So it shifts curve to left and decreases o2 sat.

O2 content decreases as a result of decrease in saturation
There you go! Thnx, that's how i built it in my head
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Quote:
Originally Posted by Renaissance View Post
There you go! Thnx, that's how i built it in my head
U are welcome
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Quote:
Originally Posted by MedicalExaminer View Post
In CO poisoning - CO binds Hb decreasing O2 saturation but increases affinity for those O2 molecules that are already bound to Hb
So it shifts curve to left and decreases o2 sat.

O2 content decreases as a result of decrease in saturation
reason increase affinity-- it is easier to remove 4t molecule of O2 than 3rd than than 2nd than first.
and the binding capacity is in reverse order .

if i remember it correctly
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