Principles of gas exchange

Question 1

effects of high altitude

Answer 1

at high altitude there is a decrease in total pressure

Question 2

each gas in a mixture is ___ of other gases present and exerts a __ according to its concentration

Answer 2

independent, pressure

Question 3

inspired air is humidified, water vapor has a

Answer 3

partial pressure

Question 4

the amount of gas dissolved in a liquid is __ to partial pressure

Answer 4

proportional

Question 5

there is a ___ relationship between partial pressure of O2 and amount dissolved

Answer 5

linear

Question 6

ways to increase diffusion of gases

Answer 6

increase membrane area
increase amount dissolved
increase partial pressure difference
decrease membrane thickness

Question 7

gases move by

Answer 7

simple diffusion

Question 8

diffusing capacity

Answer 8

the amount of a gas the lungs can transfer to the blood (O2)

Question 9

perfusion-limited

Answer 9

diffusing capacity is limited by blood flow
- need to increase blood flow to the lungs to increase amount of O2 delivered to the blood

Question 10

diffusion-limited

Answer 10

diffusing capacity is limited by rate of diffusion
- need to increase the rate of diffusion to increase the amount of O2 delivered to the blood

Question 11

diffusing capacity of O2 is

Answer 11

perfusion limited
- O2 in alveoli and the blood comes to equilibrium, therefore increasing the rate of diffusion will not add O2 to the blood, so must increase blood flow

Question 12

in disease conditions, if the O2 in the blood does not come to equilibrium with the alveoli, the diffusion capacity of O2 would now be

Answer 12

diffusion limited

Question 13

O2 in alveoli come to equilibrium 1/3 of the way through the capillary so even if blood velocity increases (exercise) the O2 in the blood will come to equilibrium with alveoli

Answer 13

important

Question 14

the pulmonary circulation is a __ pressure system compared to the systemic circulation

Answer 14

low

Question 15

congestive (left) heart failure

Answer 15

blood builds up in pulmonary circulation, pulmonary capillary pressure increases, filtration at capillaries, pulmonary edema, poor gas exchange (potential death)

Question 16

recruitment

Answer 16

open more capilaries

Question 17

if there is not decrease in TPR during exercise then

Answer 17

increase MAP, filtration in lungs, pulmonary edema, death

Question 18

distension

Answer 18

increase radius of each capillary

Question 19

3 benefits of recruitment and distension

Answer 19

decreased resistance causes decreased pressure and prevents filtration
decreases velocity of blood flow so more time for gas exchange
increases surface area for gas exchange

Question 20

effect of autonomic NS on pulmonary vascular resistance

Answer 20

not an important regulator

Question 21

effect of hypoxia (low O2)

Answer 21

always want to match air flow and blood flow
- decreased air flow = decreased O2 = vasoconstriction
- decrease air flow leads to decreased blood flow

Question 22

PO2 in the air is 160 mmHg but PO2 in alveoli is 105 mmHG, why the decrease

Answer 22

mine with dead space air
mixing with residual volume air
air is humidified (water vapor added)

Question 23

shunting

Answer 23

some blood does not go past alveoli, the PO2 in this blood stays at PO = 40 mmHg