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2 Physiology Test 3
Oxygen Exchange/Transport 1
18
Medical
Graduate
03/25/2009

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Cards

Term
Fick's Law
Definition
The flow of oxygen, or any gas, (V) across a barrier is proportinal to its diffusing capacity (Dl)in the barrier and its concentration gradient across the barrier (P1 - P2).

V = Dl x (P1 - P2)
Term
Graham's Law
Definition
Diffusion is inversely proportional to the square root of the molecular weight of the gas
Term
What is the rate limiting step in oxygen diffusion?
Definition
Diffusion in the tissues because the distances are much longer
Term
How does the CV system minimize diffusion distance?
Definition
By increasing capillary density, increasing the rate of delivery of oxygenated blood to the tissues by increasing flow rates or by increasing the oxygen carrying capability of the blood
Term
How is methemoglobin formed?
Definition
When iron in hemoglobin is oxidized by nitriles or sulfonamides. Incapable of binding oxygen
Term
What is the O2 carrying capacity of blood?
Definition
20.1 mL of O2 per 100 mL of blood

O2 deliver to the tissues would be about 1000 mLs of O2 per minute. Normal consumption is about 250 mls/min
Term
In what direction of the curve does affinity decrease/increase?
Definition
Decrease - to the right

Increase - to the left
Term
Does a left shift increase or decrease oxygen loading in the lung?
Definition
It increases oxygen loading in the lung.
Term
How does increased temp affect the curve?
Definition
Right shift
Term
How does increased pH affect the curve?
Definition
Shift to the Left
Term
How does increased PCO2 affect the curve?
Definition
Shift to the right
Term
How does increased 2,3 DPG affect the curve?
Definition
Shift to the R
Term
What is myoglobin?
Definition
It is a heme containing molecule that is unlike hemoglobin in that it is a monomer and shows no allosteric cooperativity. It begins unloading O2 around at a pressure of 20mmHg.
Term
How does CO affect hemoglobin? Which way does it shift the curve?
Definition
It binds Hb with a 240 fold increased affinity. CO significantly increases the affinity of Hb for oxygen. Shifts the curve way to the Left. Therefore, the affected Hb will not be able to unload oxygen at the level of the tissues.
Term
Which way does nitric oxide shift the curve?
Definition
To the left.
Term
How does venous blood compare to arterial blood in terms of the curve?
Definition
Curve is shifted to the right in venous blood due to the Bohr effect vs. arterial blood. Makes sense b/c arterial blood should facilitate unloading moreso than venous blood.
Term
Why do dialysis patients normally become anemic?
Definition
Because EPO is synthesized in the kidneys, and this directly affects the levels of RBCs in the blood. If the kidneys are not functioning or are removed, the levels of RBCs will be low.
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