Lecture 25: Blood Gas Transport

Question 1

Describe the pressure difference that cause oxygen to diffuse into the pulmonary capillary

Answer 1

Initial pressure difference that causes oxygen to diffuse into the pulmonary capillary= 104-40= 64 mmHG

Arterial minus venous

In the pulmonary capillary the blood PO2 rises close to that in the alveolar air by the time the blood has moved 1/3 the distance through the capillary.

Question 2

What factors allow the diffusion capacity of oxygen to increase during exercise.

Answer 2

A person may require 20x the normal amount of oxygen during exercise.

Diffusing capacity of oxygen increases 3X during exercise:

There is an increased surface area of capillaries participating in diffusion.

There is a more nearly ideal V/Q ratio in the upper parts of the lungs.

Question 3

Zone of rest vs. Zone of exercise:

Answer 3

zone 2 at rest –> Zone 3 in exercise

Question 4

What factors determine tissue PO2?

Answer 4

Rate of oxygen transport to the tissues

Rate of Oxygen consumption by the tissues

Question 5

Describe the effects of blood flow and metabolic rate on peripheral tissue PCO2

Answer 5

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Question 6

Normal intracellular P02:

Answer 6

Normal rance 5-40, MEAN of 23 mmHG

Question 7

Oxygen Utilization Coefficient:

Answer 7

Percentage of blood that gives up its oxygen

In exercise: 75-85%

Question 8

Compare oxygen saturation in venous blood to that in the arterial blood in relation to how much oxygen is bound to heme groups.

Answer 8

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Question 9

Explain how hemoglobin can be viewed as a tissue oxygen buffer system.

Answer 9

In order to release 5 ml of oxygen/dl of blood:
P02 must fall to about 40 mm Hg
Tissue PO2 can not rise above this level

When PO2 is high (pulmonary capillaries), oxygen binds with hemoglobin
When PO2 is low (tissue capillaries) oxygen is released form hemoglobin.

Question 10

Relate PO2 and oxygen saturation to the oxygen-hemoglobin dissociation curve.

Answer 10

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Question 11

Relate PO2 to quantity of bound oxygen per unit of blood

Answer 11

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Question 12

Relate pH to oxygen-hemoglobin dissociation curve.

Answer 12

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Question 13

List and explain factors that shift the oxygen-hemoglobin dissociation curve to the right.

Answer 13

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Question 14

What is the Bohr effect and what effect does it have on the oxygen dissociation curve?

Answer 14

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Question 15

List and describe the 3 ways carbon dioxide is transported in the blood, give approximate percentage of carbon dioxide that is transported by each mechanism.

Answer 15

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Question 16

define bohr effect and haldane effect and explain their effects on the oxygen-hemoglobin dissociation curve.

Answer 16

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Question 17

Explain why blood might be bright red in carbon monoxide poisoning.

Answer 17

In carbon monoxide poisoning, oxygen content of blood is greatly reduced, but PO2 of the blood may be normal. Therefore blood may be bright red.