Chapter 40 - Guyton Flashcards Preview

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Flashcards in Chapter 40 - Guyton Deck (20):
1

The transport of oxygen and carbon dioxide is dependent on what two factors?

diffusion (partial pressure difference) and blood flow

2

How can blood still be oxygenated during strenuous exercise, when the time it remains in the pulmonary capillaries may be reduced by up to one half normal?

increased capillary surface area, more ideal ventilation-perfusion ratio in the upper lung, blood is normally oxygenated in the first 1/3 of the pulmonary capillary so even when the time is reduced it will still cause full oxygenation

3

If cell metabolism of oxygen increases, how is interstitial Po2 affected?

decreases

4

If blood flow increases, how is interstitial Po2 affected?

increases

5

What is the primary difference between the diffusion of oxygen and carbon dioxide?

carbon dioxide can diffuse about 20 times as rapidly as oxygen

6

How would decreased blood flow affect interstitial Pco2?

increases

7

How would increased tissue metabolism affect interstitial Pco2?

increases

8

Under normal conditions, oxygen is carried to the tissues almost entirely by ____________.

hemoglobin

9

What is depicted on the oxygen-hemoglobin dissociation curve?

progressive increase in the percentage of hemoglobin bound with oxygen as blood Po2
increases, which is called the per cent saturation of hemoglobin

10

Usual oxygen saturation of systemic arterial blood averages?

97%

11

Under normal conditions, about __ mL of oxygen are transported from the lungs to the tissues by each ___ mL of blood flow.

5; 100 (97% to 75% hemoglobin saturation on passing through the tissue capillaries)

12

What can cause up to a 20-fold increase in oxygen transport to the tissues in well trained athletes?

3-fold increase in oxygen delivery to tissues (oxygen dissociates from hemoglobin), 6-7 times increase in cardiac output

13

The percentage of the blood that gives up its oxygen as it passes through the tissue capillaries is called the __________ ___________.

utilization coefficient

14

What is the "oxygen buffer" function of blood hemoglobin?

the level of alveolar oxygen may vary greatly—from 60 to more than 500 mm Hg Po2—and still the Po2 in the peripheral tissues does not vary more than a few millimeters from normal

15

Shifts the oxygen-hemoglobin dissociation curve to the right.

increased hydrogen ions (pH), increased CO2, increased temperature, increased 2,3 biphosphoglycerate (BPG)

16

Bohr effect

binding of carbon dioxide with hemoglobin tends to displace oxygen

17

As ADP concentration increases, rate of oxygen usage ________.

increases

18

How is carbon dioxide transported in the blood?

dissolved, hemoglobin, bicarbonate (most)

19

Haldane effect

binding of oxygen with hemoglobin tends to displace carbon dioxide

20

What is the resporatory exchange ratio (R)?

R = rate of carbon dioxide output / rate of oxygen uptake (carb use = 1.0; fat use = 0.7, avg. is 0.825)