S3_L4: Gas Exchange

Question 1

It is the diffusion of oxygen and carbon dioxide between the alveoli and pulmonary capillaries in the lungs, and between the systemic capillaries and cells throughout the body. It is the diffusion of these gases moving in opposite directions.

Answer 1

Gas exchange

Question 2

What law states, “in a mixture of gases, the total
pressure equals the sum of the partial pressures
exerted by each gas; 1 ATM = sum of gas partial pressures”?

Answer 2

Dalton’s Law of Partial Pressures

Question 3

Enumerate the 3 sites of gas exchange

Answer 3

1. Alveolocapillary membrane (blood-tissue level)
2. Alveolocapillary lung interphase
3. Cellular capillary level

Question 4

Gases diffuse along their partial pressure gradient, from regions of (1)___ partial pressure to regions of (2)___ partial pressures

Answer 4

1. high
2. low

Question 5

What law states, “The amount of gas which dissolves in a liquid is proportional to the partial pressure and solubility of the gas”?
This law explains the relationship of partial
pressures and solubility of a gas.

Answer 5

Henry’s Law

Question 6

What kind of respiration uses O2 for the production of
ATP?

Answer 6

Internal respiration

Question 7

What are the 3 factors that affect external respiration?

Answer 7

1. Surface area and structure of the respiratory membrane
2. Partial pressure gradients
3. Matching alveolar airflow to pulmonary capillary blood flow

Question 8

What is the alveolar PO2?

Answer 8

104 mmHg

Question 9

Enumerate the 3 factors that explain the differences
in partial pressures between alveoli and ambient air

Answer 9

1. humidification
2. Gas exchange at the alveolo-capillary level
3. Mixture of old and new air

Question 10

If a bronchus is full of mucus, what happens to the PO2
to the distal alveoli?
A. Increases
B. Decreases
C. No effect

Answer 10

B. Decreases

Question 11

What is the response of the VA/Q coupling to a ↓PO2?
A. Arteriolar constriction
B. Bronchole dilation
C. None

Answer 11

A. Arteriolar constriction

Question 12

What is the response of the VA/Q coupling to a ↑PO2?
A. Arteriolar constriction
B. Bronchole dilation
C. None

Answer 12

B. Bronchole dilation

Question 13

What explains physiological shunt?

Answer 13

VA/Q = 0

mixture of a portion of deoxygenated blood with oxygenated blood

Question 14

Diffuses from pulmonary capillaries into alveoli and from cells into systemic capillaries

Answer 14

Carbon dioxide

Question 15

Diffuses from alveoli into pulmonary capillaries and from systemic capillaries into cells

Answer 15

Oxygen

Question 16

During ventilation-perfusion coupling, arterioles respond to changes in (1)___ and bronchioles respond to changes in (2)___.

Answer 16

1. PO2
2. PCO2

Question 17

Low PO2 causes arterioles to (1)___
High PCO2 causes bronchioles to (2)___

Answer 17

1. constrict
2. dilate

Question 18

Arterial oxygen should be 104 mmHg, but during the equilibration process in internal respiration, it becomes ___ at the pulmonary venular end

Answer 18

100 mmHg

Question 19

Determine the corresponding descriptions of zone airflow into the lungs in the upright position

1. intermittent blood flow
2. during systole, the BP of capillary is
   greater than pressure of alveolus and gas exchange occurs here
3. most aerated and most ventilated bc air is lighter than water & blood
4. area of 100% perfusion
5. present in pathologic lungs

A. Zone 1
B. Zone 2
C. Zone 3

Answer 19

1. B
2. B
3. A
4. C
5. A