Physiology 3 + 4

Question 1

Anatomical dead space?

Answer 1

Some inspired air remains in the airways where it is not available for gas exchange

Question 2

Pulmonary ventilation?

Answer 2

Pulmonary Ventilation (L) = tidal volume (L/breath) x Respiratory Rate (breath/min)

Question 3

Why is alveolar ventilation less than pulmonary ventilation?

Answer 3

Because of the presence of anatomical dead space

Alveolar ventilation = (tidal volume – dead space volume) x Respiratory Rate

Question 4

Pulmonary ventilation?

Answer 4

Volume of air breathed in and out per minute

Question 5

Alveolar ventilation?

Answer 5

Volume of air exchanged between the atmosphere and alveoli per minute

Question 6

Pulmonary ventilation equation?

Alveolar ventilation equation?

Answer 6

Pulmonary Ventilation = Tidal Volume x Respiratory Rate

Alveolar Ventilation = (Tidal Volume – Dead Space) x Respiratory Rate

Question 7

Gas transfer within the body depends on? (2)

Answer 7

Ventilation: the rate at which gas is passing through the lungs.

Perfusion: the rate at which blood is passing through the lungs

Question 8

Alveolar dead space?

Increased?

Answer 8

Ventilated alveoli which are not adequately perfused with blood are considered as alveolar dead space

In healthy people, the alveolar dead space is very small and of little importance
- the alveolar dead space could increase significantly in disease

Question 9

How is ventilation perfusion match achieved?

Answer 9

Accumulation of CO2 in alveoli as a result of increased perfusion decreases airway resistance leading to increased airflow

Increase in alveolar O2 concentration as a result of increased ventilation causes pulmonary vasodilation which increases blood flow to match larger airflow

Question 10

Effects of O2 on pulmonary vs systemic arterioles

Answer 10

Question 11

Which 4 factors influence the rate of gas exchange across the alveolar membrane?

Answer 11

1 - Partial Pressure Gradient of O2 and CO2

2 - Diffusion Coefficient for O2 and CO2

3 - Surface Area of Alveolar Membrane

4 - Thickness of Alveolar Membrane

Question 12

What determines pressure gradient of a gas?
Why is this important?
Law?

Answer 12

Partial pressure of a gas = determines the pressure gradient for that gas

Important because gases move across cell membranes by pressure gradient

Dalton’s Law of Partial Pressures–>
Total pressure exerted by gaseous mixture = sum of partial pressures of each gas in mixture