Lecture 24 Pulmonary Gas Exchange

Question 1

Major components of air and compositions

Answer 1

N (78.09%)
O2 (20.95%)
Ar (0.93%)
CO2 (0.03%)

Question 2

dalton’s law

Answer 2

total pressure of mixture of gasses - sum of partial pressure of gases

Question 3

Boyle’s Law

Answer 3

at fixed temp, pressure and volume are inversely proportional

Question 4

Henry’s law

Answer 4

@ constant temp, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid

Question 5

partial pressure is determined by

Answer 5

[dissolved gas] and solubility of gas

Question 6

solubility constant of O2 and partial pressure (mmHG)

Answer 6

0.024

150

Question 7

solubility constant of CO2 and partial pressure (mmHG)

Answer 7

0. 57

0. 21

Question 8

why is the partial pressure of CO2 so much less than O2

Answer 8

CO2 is more soluble than O2 (greater solubility constant) so it exerts a partial pressure about 1/20th of O2

Question 9

water vapor pressure

Answer 9

partial pressure exerted on water so it can escape from the liquid phase to the gas phase

depends on the temperature of the water (low temps = low pressure)

Question 10

factors that affect the rate of gas diffusion in a fluid (5)

Answer 10

solubility of gas
cross sectional area of fluid
distance of diffusion 
molecular weight of gas
temperature of fluid

Question 11

factors that control [oxygen] in alveoli

Answer 11

rate of absorption of O2 in blood

rate of new O2 entry into lungs

Question 12

factors that control [CO2] in alveoli

Answer 12

rate of CO2 excretion (increase in rate of secretion = increase in alveolar pCo2)
alveolar ventilation  (ventilation increase causes decrease in PCO2)

Question 13

factors that determine how rapidly gas will pass through respiratory membrane

Answer 13

membrane thickness
membrane surface area
digestion coefficient of gas in the membrane substance
partial pressure difference between the two sides of the membrane

Question 14

what is shunted blood?

Answer 14

venous blood that doesn’t get oxygenated when moving through lung capillaries therefore remaining deoxygenated and entering the left ventricle