Physiology L3 - Gas Exchange

Question 1

What is meant by anatomical dead space?

Answer 1

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

Question 2

What is pulmonary ventilation?

Answer 2

It is the volume of air breathed in and out per minute

Question 3

What is alveolar ventilation?

Answer 3

Is the volume of air exchanged between the atmosphere and alveoli per minute

Question 4

How to you calculate pulmonary ventilation?

Answer 4

Tidal volume (L/breath) x respiratory rate (breath/min)

Example:
0.5L x 12 breath/min = 6L/min
under resting conditions

Question 5

Why is alveolar ventilation less than pulmonary ventilation?

Answer 5

Because the alveolar ventilation does not include the precedes of anatomical dead space

Question 6

How do you calculate alveolar ventilation?

Answer 6

(Tidal volume - dead space volume) x respiratory rate

Example:
0.5-0.15) x 12 = 4.2L/min
(under resting conditions

Question 7

Even though 500ml of air is moved in and our of the respiratory system with each breath why is only 30ml actually exchanged?

Answer 7

The presence of anatomical dead space equalling 150ml

Question 8

How is pulmonary ventilation increase e.g. during exercise?

Answer 8

Both the depth (tidal volume) and rate of breathing (RR) increase.

Question 9

Why is it more advantageous to increase the depth of breathing over the rate when exercising?

Answer 9

Because of anatomical dead space. By increasing depth more air is exchanged with each breath between atmosphere and alveoli so alveolar ventilation increases

Question 10

Describe the difference in breathing pattern between quiet breathing at rest and deep breathing?

Answer 10

1. Total volume of breath increases
2. The respiratory rate decreases
3. Dead space remains the same
4. Pulmonary ventilation remains the same swell
5. ALVEOLAR VENTILATION INCREASES

The total volume of each breath is 500ml at at respiratory rate of 12breath/min. which means the pulmonary ventilation is 6000ml/min and the alveolar ventilation is 4200ml/min. However by deep breathing the total volume of each breath is 1200ml and respiratory rate is 5breath/min. This means that there is a pulmonary ventilation is still 6000ml/min but the alveolar ventilation has increases to 5250ml/min. The dead space volume stays the same!

Question 11

Describe the difference in breathing pattern between quiet breathing at rest and shallow, sharp breathing?

Answer 11

1. Total volume of breath decreases
2. The respiratory rate increases
3. Dead space remains the same
4. Pulmonary ventilation remains the same swell
5. ALVEOLAR VENTILATION DECREASES

The total volume of each breath is 500ml at at respiratory rate of 12breath/min. which means the pulmonary ventilation is 6000ml/min and the alveolar ventilation is 4200ml/min. However by deep breathing the total volume of each breath is 150ml and respiratory rate is 40breath/min. This means that there is a pulmonary ventilation is still 6000ml/min but the alveolar ventilation has decreases to 0ml/min. The dead space volume stays the same!

Question 12

What is ventilation perfusion?

Answer 12

The transfer of gases between the body and atmosphere.

It is a measurement used to assess the efficiency and adequacy of the ratio of the amount of air reaching the alveoli to the amount of blood reaching the alveoli

Question 13

What does ventilation perfusion depend on?

Answer 13

1. Ventilation - the rate at which gas is passing through the lungs
2. Perfusion - the rate at which blood is passing through the lungs