DSA - Lung Volumes

Question 1

What are the accessory muscles for inspiration

Answer 1

Sternocleidomastoid (elevates sternum)

Scalenes (elevate and fix upper ribs)

Question 2

What are the principal muscles of inspiration

Answer 2

External intercostals (elevate ribs)

Question 3

What are the active muscles for expiration

Answer 3

Internal intercostal muscles

Abdominals (depress lower ribs)

Rectus abdominis

External/Internal oblique

Transverse abdominis

Question 4

Define residual volume

Answer 4

Volume of air that cannot be forced out

Cannot be determined by spirometry

Question 5

Define tidal volume

Answer 5

The amount of air inspired or expired in a single breath

Question 6

Define inspiratory reserve volume

Answer 6

Volume of air breathed above tidal volume

Question 7

Define expiratory reserve volume

Answer 7

Volumes of air that can be forced out in addition to tidal volume

Does not include residual volume

Requires activation of expiratory muscles (active respiration)

Question 8

Define vital capacity and give the equation

Answer 8

Amount of air that can be maximally inspired following a maximal expiration

VC = IRV + Vt + ERV

Question 9

Define inspiratory capacity and give the equation

Answer 9

Capacity of air that can be maximally inspired following a normal exhale

IC = Vt + IRV

Question 10

Define functional residual capacity and give the equation

Answer 10

Amount of air that remains in the lungs following a normal expiration

FRC = ERV + RV

Question 11

Define total lung capacity and give the equation

Answer 11

Maximal volume to which lungs can be expanded with great effort

TLC = IC + FRC = VC + RV

Question 12

What are three ways to measure residual volume

Answer 12

Nitrogen-washout technique

Helium dilution

Body plethysmography