Pulmonary Physiology: Ventilation

Question 1

Is CO2 a large contributor of partial pressure to atmospheric air?

Answer 1

No!

Question 2

What is PACO2 (alveoli)?

Answer 2

40 mmHg

Question 3

What is PAO2 (alveoli)?

Answer 3

104 mmHg

Question 4

What is PvO2 (venous)?

Answer 4

40 mmHg

Question 5

What is PvCO2 (venous)?

Answer 5

46 mmHg

Question 6

What is PaO2 (arterial)?

Answer 6

100 mmHg

Question 7

What is PaCO2 (arterial)?

Answer 7

40 mmHg

Question 8

Why is arterial PO2 4 mmHg less than alveolar PO2?

Answer 8

Some blood from the bronchial veins drains into the pulmonary veins, diluting the blood slightly.

Question 9

What are the PO2 and PCO2 in cells?

Answer 9

PO2 is 40 mmHg and PCO2 is 46mmHg (same as venous blood!)

Question 10

Are the partial pressures of gases in the body at steady state, or equilibrium?

Answer 10

steady state

Question 11

How is minute ventilation calculated? What are the units?

Answer 11

rate x tidal volume = mL/min

Question 12

What is the anatomic dead space? What is an average anatomic dead space volume?

Answer 12

The inhaled air that does not make it to the respiratory zones of the lungs. Avg is around 150 mL

Question 13

The Fowler washout measures the anatomic dead space by monitoring ___ levels in the exhaled air after an initial inhalation of pure oxygen.

Answer 13

nitrogen

Question 14

What is alveolar dead space? Is it normal?

Answer 14

Alveoli that are ventilated but not perfused - so no gas exchange happens. Only pathological.

Question 15

When ventilation fails, PACO2 will increase, therefore so will ______ PCO2.

Answer 15

arterial

Question 16

How does the Poiseulle equation apply to ventilation?

Answer 16

Flow is proportional to the 4th power of the radius of the airway

Question 17

Turbulent flow requires ______ (more or less) pressure to move air while laminar flow requires ______ pressure to move the air.

Answer 17

turbulent needs more pressure, laminar needs less

Question 18

Inspired air flows to terminal bronchioles down the pressure gradient, while the final movement of air into the alveoli occurs by ________.

Answer 18

diffusion

Question 19

Explain why small airways have a total lower resistance than large airways despite being individually much smaller.

Answer 19

They are in parallel, and their total resistance equals the sum of the reciprocals of each individual small airway.

Question 20

Sympathetic (beta-2) stimulation results in _________.

Answer 20

bronchodilation

Question 21

What is functional residual capacity?

Answer 21

Expiratory reserve volume + residual volume. Its the air that is leftover in the lungs after a normal exhale.

Question 22

What is vital capacity?

Answer 22

Expiratory reserve volume + inspiratory capacity. Its as much air as you can possibly inhale at once after exhaling really hard and inhaling really hard.

Question 23

How is residual volume measured?

Answer 23

Helium dilution method: A person inhales helium from a tank with known volume and helium concentration, then the concentration of helium in the tank is measured and the volume of the lungs is calculated using C1V1 = C2V2

Question 24

The lungs’ tendency to collapse is due to two things. What are they?

Answer 24

Alveolar surface tension - 2/3

Elastic recoil - 1/3