Respiration 4

Question 1

At both ________ capillary and _______ capillary levels, gas exchange involves _________ of O2 and CO2 ______ partial pressure gradients

Answer 1

pulmonary
tissue
simple diffusion
down

Question 2

Partial pressure exerted by each gas in a mixture equals the

Answer 2

(total pressure) x (the fractional composition of this gas in the mixture)

Question 3

Factors influencing the rate of net diffusion of a substance across a membrane ( Fick’s Law of Diffusion)

Answer 3

Concentration/partial pressure
Alveolar surface area
Solubility of gas
Diffusion coefficient/MW
Alveolar/capillary distance

Question 4

When CO2 is at equilibrium at the same partial pressure as O2, more CO2 dissolves. Why?

Answer 4

CO2 dissolves better (more soluble) than H2O because, at equilibrium, PO2 in the air and water is equal.
- Low O2 solubility means unequal concentrations

Question 5

As time goes by the diffusion gradient ______

Answer 5

weakens

Question 6

Constant Respiration keeps __________ functional

Answer 6

pressure gradients

Question 7

Patterns of gas transfer in fish, birds, and mammals

Answer 7

Fish gills- counter current

Avian lungs- crosscurrent

Mammalian lungs- uniform pool

Question 8

What ensures that no gas is lost on the way?

Answer 8

Only 2 places of interchange:

• at the capillary bed of alveoli
• and capillary bed at tissue level

Only at these places are the requirements for diffusion met (Fick’s law)