Haemoglobin

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Aerlinn
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Haemoglobin

Post by Aerlinn » Wed Nov 16, 2005 5:24 am

I had this question. Oxygen carrying molecules are found in many animals and even in some bacteria. These respiratory pigments combine reversibly with oxygen and increase the oxygen carrying capacity of blood. Below is a graph showing the percentage saturation of the respiratory pigment haemoglobin with oxygen at different concentrations of oxygen. An area of the body where the saturation is likely to be that indicated on the graph with an X is

A exercising muscle
B lungs
C aorta
D the pulmonary vein.

The Graph it refers to was something like this shape (except the curve was a smoother curve). The curve is also meant to be labelled 'haemoglobin'.
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mith
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Post by mith » Wed Nov 16, 2005 5:55 am

well, the graph shows low concentration, which answer is the part of the body that carries the deoxygenated blood?
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Post by Aerlinn » Wed Nov 16, 2005 6:04 am

Erm... I'm thinking it's either A or B, but I'm not sure which. And with the lungs, it would depend on whether it was incoming or outcoming blood...
And if someone can, can you please give an explanation of some sort? I'm not entirely sure with the whole thing :S
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Post by Navin » Wed Nov 16, 2005 12:02 pm

I may be wrong but here is my answer:
I would pick A; the exercising muscles.

Oxygen concentrations at the muscles are low as oxygen is used up fast via respiration.

So, oxyhaemoglobin becomes haemoglobin, releasing its oxygen molecules for the muscles.

This happens as oxyhaemoglobin is unstable and the reaction reverses at low concentrations of oxygen.

(If theres something wrong with my explanation pls tell me - im very uncertain with my answer)
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Post by Geordie Boy » Wed Nov 16, 2005 12:57 pm

Ah the oxygen dissociation curve. By far the most stupid graph ever created. I mean who would have two axis essentially showing the exact same thing? :roll:

Navin is right its the exercising muscles.

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Post by biostudent84 » Wed Nov 16, 2005 10:28 pm

Geordie Boy wrote:Ah the oxygen dissociation curve. By far the most stupid graph ever created. I mean who would have two axis essentially showing the exact same thing? :roll:

Navin is right its the exercising muscles.


I would not agree with the excercising muscles. Blood coming away from those capillaries normally has a partial pressure 40 mmHg. Blood going to those capillaries normally has a partial pressure of 95 mmHg. So the area of blood right in the capillaries would have an -average- of 65-70 mmHp partial pressure. Blood leaving the veins, heading back to the heart would have the lowest oxygen concentration.

And...they are not the same thing...otherwise it would be a directly linear relationship. I know my eyes are terrible, but I don't think that graph is a straight line. ;) (No sarcasm intended...just wanted to say it :) )

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Post by canalon » Thu Nov 17, 2005 3:13 am

biostudent84 wrote: And...they are not the same thing...otherwise it would be a directly linear relationship. I know my eyes are terrible, but I don't think that graph is a straight line. ;) (No sarcasm intended...just wanted to say it :) )


And they are not the X axis shows the concentration of oxygen probably in the lung, and the Y axis shows the saturation of haemoglobin. I bet the smoother shape was rather sigmoïd...
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Post by Geordie Boy » Thu Nov 17, 2005 8:37 am

No i am pretty sure that the x axis shows oxygen partial pressure k/Pa and the Y shows oxygen saturation of heamoglobin.

It would not be a straight line they would go up and down together. I guess its just like any standard curve but i am just sick of graphs, there is really no need to draw a graph to tell you that increased saturation means increased pressure and vice versa. It would have been more useful to plot Saturation or pressure against Co2 concentration.

Anyway, at rest the blood only usually gives up about 23-25% of its oxygen leaving the blood in the veins still 75-77% saturated. This leaves plenty of reserve in case of excercise. Heamoglobin gives up more oxygen the higher the concentration of CO2, which would highest be in the tissue of respiring muscles.

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Post by MrMistery » Thu Nov 17, 2005 7:18 pm

@Kyle
Do my eyes deceive me or your answer is not included in the possible answers?
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