Term
| What is the average alveolar oxygen partial pressure? |
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Definition
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Term
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Definition
The flow of oxygen (V) across a barrier is proportional to its diffusing capacity (Dl) in the barrier and its concentration gradient across the barrier (P1 - P2)
V = DL x (P1-P2) |
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Term
| What factors affect diffusion according to Graham's Law? |
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Definition
Diffusion is inversely proportional to the square root of the molecular weight of the gas and the thickness of the barrier
Diffusion is proportional to the surface area and the solubility of the gas in water |
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Term
| How does the vascular system minimize diffusion distances? |
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Definition
| Increasing capillary denisty (recruitment or angiogenesis), increasing the rate of delivery of oxygenated blood to the tissues by increasing flow rates (keeps the partial pressure gradient as high as possible) or by increasing the oxygen carrying capability of the blood (erythropoiesis) |
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Term
| In what tissues is the diffusing capacity a rate limiting step? |
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Definition
NOT in the lungs; in the lungs, the pressure gradient is the important factor of the alveolar gas exchange equation
Usually in tissues where the distances are much greater |
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Term
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Definition
Henry's law states that the amount of oxygen dissolved in water is the product of the solubility coefficient times the partial pressure of oxygen
0.003 ml of O2 will dissolve in each 100 ml of blood per mm Hg of pressure |
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Term
| What is the 02 carrying capacity of blood? |
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Definition
20.1 ml of O2 per 100 ml blood plus the very small amount of O2 dissolved in the blood
The normal O2 consumption is 250 mls/minute |
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Term
| In what cases might hyperbaric O2 therapy be useful? |
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Definition
Carbon monoxide poisoning
Decompression sickness
Gas gangrene |
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Term
| When do the effects of anemia become apparent? |
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Definition
| What patients exercise and cannot meet their metabolic requirements even after increasing blood flow to their tissues |
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Term
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Definition
| A small peptide formed in the kidney in response to stimuli related to the oxygen carrying capacity of blood; the hormone stimulates red blood cell formation |
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Term
| Where are the receptors for the erythropoietin reflex located? |
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Definition
| Near the renal glomerulus and may be located within the juxtaglomerular apparatus; this is an ideal location for oxygen sensors since the kidneys receive a large and stable percentage of the cardiac output |
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Term
| How long is the programming and production phase of the erythropoietin response? Why is this adventageous? |
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Definition
Between 10 and 24 hours
This is adventageous because increasing hematocrit in response to acute oxygen demands would put stress on the heart |
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Term
| What is used to calculate the total Diffusion Capacity of the lung? |
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Definition
| Carbon monoxide is generally used in this technique because it is rapidly taken up by the red blood cell and the partial pressure of CO in the plasma remains very low |
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Term
| Where are the receptors for the erythropoietin reflex located? |
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Definition
| Near the renal glomerulus, and may be located within the juxtaglomerular apparatus; this is an ideal location for oxygen sensors since the kidneys recieve a large and stable percentage of the cardiac output |
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