Respiratory Volume and Capacities

Question 1

Define Tidal Volume and state the volume

Answer 1

Volume of air entering/leaving the lungs during a single breath during quiet breathing

500mL

Question 2

Define Inspiratory Reserve Volume and state the volume

Answer 2

Extra volume of air that can be maximally inspired over the tidal volume, during forced inspiration

3000mL

Question 3

Define Inspiratory Capacity and state the volume

Answer 3

Maximum volume of air inspired at the end of quiet expiration

3500mL

Question 4

What makes up the Inspiratory Capacity?

Answer 4

Tidal Volume and Inspiratory Reserve Volume

Question 5

Define Expiratory Reserve Volume and state the volume

Answer 5

Extra volume of air expired during forced expiration

1000mL

Question 6

Define Residual Volume and state the volume

Answer 6

minimum volume of air remaining in lungs after maximal expiration

1200mL

Question 7

Define Functional residual capacity and state the volume

Answer 7

Volume of air in lungs at the end of normal expiration

2200mL

Question 8

What makes up Functional residual capacity?

Answer 8

Expiratory Reserve Volume and Residual volume

Question 9

Define Vital capacity and state the volume

Answer 9

Maximum volume of air that can be moved out during a single breath following maximal inspiration (forced inspiration and expiration)

4500mL

Question 10

What makes up the vital capacity?

Answer 10

Inspiratory Reserve Volume, Tidal volume and Expiratory Reserve Volume

Question 11

Define Total Lung Capacity and state the volume

Answer 11

Maximum volume of air the lungs can hold

5700mL

Question 12

What makes up the Total Lung Capacity

Answer 12

Vital capacity and Residual volume

Question 13

Define Pulmonary Ventilation

Answer 13

Volume of air breathed in and out per minute

Question 14

Formula for Pulmonary Ventilation

Answer 14

Tidal Volume x Respiratory Rate

Question 15

Explain anatomical dead space

Answer 15

• Not all the inspired air gets down to the site of exchange in the alveoli
• About 150mL is stuck in the conducting airways and are not available for gas exchange
• Out of the 500mL that moves in and out of each breath, only 350mL is exchanged between atmosphere and alveoli

Question 16

What is the effect of anatomical dead space on exchange of tidal volume?

Answer 16

• At the end of inspiration, respiratory airways are filled with 150mL of fresh atmospheric air from inspiration
• During subsequent expiration, 500mL is expired to the atmosphere (150mL fresh air, 350mL old air that participated in gas exchange)
• in the same expiration, 500mL of gas leave the alveoli (150mL old air, 350mL fresh air)
• On the next inspiration, 500mL of gas enter the alveoli (150mL old air that enters first, 350mL fresh air from the atmosphere)
• In the same inspiration, 150mL remain in conducting airways while 350mL reaches the alveoli first

Question 17

Define Alveolar Ventilation

Answer 17

Volume of air exchanged between atmosphere and alveoli per minute

Question 18

Formula for alveolar ventilation

Answer 18

(Tidal volume-Dead space volume) x Respiratory rate