Lung volumes and capacities

Question 1

tidal volume

Answer 1

volume of air entering lungs during a single inspiration
~ equal to volume leaving on expiration
during quiet breathing, ~ 500ml

Question 2

inspiratory reserve volume

Answer 2

maximal amount of air that can be increased above the resting tidal volume during deepest inspiration
~ 3000ml

Question 3

functional residual capacity (FRC)

Answer 3

large volume of air in lungs after expiration of resting tidal volume
~2400ml

Question 4

expiratory reserve volume (ERV)

Answer 4

through maximal active contraction of expiratory muscles, much more of air remaining after resting tidal volume can be expired
~1200ml

Question 5

residual volume

Answer 5

air remaining after maximal active expiration

~1200ml

Question 6

vital capacity

Answer 6

maximal volume of air that can be expired after maximal inspiration
expires resting tidal volume, inspiratory reserve volume and expiratory reserve volume

Question 7

forced expiratory volume in 1 sec

Answer 7

maximal inspiration and maximal expiration as fast as possible
fraction of total forced vital capacity expired in 1 sec
healthy ~80% of vital capacity

Question 8

obstructive lung diseases

Answer 8

increased airway resistance

less than 80% fev1 as they cannot move air quickly through narrowed airways

Question 9

restrictive lung diseases

Answer 9

normal airway resistance - impaired respiratory movements due to abnormalities in lung tissue, pleura, chest wall or neuromuscular machinery
reduced vital capacity but normal ratio of fev1 : vital capacity