DSA 1: Lung Volumes and Capacity

Question 1

What is tidal volume?

Answer 1

Amount of air inspired or expired in a single breath

Question 2

What is normal tidal volume?

Answer 2

500 mL

Question 3

What is residual volume?

Answer 3

air that stays in lungs and cannot be forced out

Question 4

What is inspiratory reserve volume?

Answer 4

extra air you take in when you inhale

Question 5

What is expiratory reserve volume?

Answer 5

Additional volume that can be exhaled greater than tidal volume

• does not include residual volume
• activation of expiratory muscles

Question 6

Draw the volumes graph and label it

Answer 6

Ok

Question 7

What is total lung capacity?

Answer 7

Maximal volume of air your lungs can take in

Question 8

How do you calculate total lung capacity?

Answer 8

TLC = IC + FRC + VC + RV = ERV + RV + IRV + VT

IC = inspiratory capacity
FRC = functional residual capacity 
VC = vital capacity
RV = residual volume
ERV - expiratory reserve volume
IRV - inspiratory reserve volume
VT = tidal volume

Question 9

What is functional residual capacity?

When supine, there is ______ FRC

Answer 9

Amount of air that remains in lungs following a normal expiration that prevents alveoli collapse

reduced

Question 10

How do you calculate functional residual capacity?

Answer 10

FRC = ERV + RV

Question 11

What is vital capacity?

What factors can affect this? (generally)

Answer 11

• how much air you can inhale after exhaling hard (maximally)
• changes in lungs and breathing muscles structure/elasticity/strength, air flow resistance

Question 12

How do you calculate vital capacity?

Answer 12

VC = IR V + VT + ERV

Question 13

What is inspiratory capacity?

Answer 13

how much air you can inhale after normal exhaling

Question 14

How do you calculate inspiratory capacity?

Answer 14

IC = VT + IRV

Question 15

How do these methods work when measuring residual volume?
Helium Dilution
Body Plethysmograph
Nitrogen-Washout Technique

Answer 15

1) Helium Dilution: Inhale known quantity of helium. The change in concentration allows determination of FRC.
2) Body Plethysmograph: breathe in box, lung pressure and box pressure changes inversely proportional (via Boyles law)
3) Nitrogen-Washout Technique: Breath in 100% oxygen and expired gas is collected until nitrogen measures 0. Using math, FRC is determined.

Question 16

How does lung volume change with age?

Answer 16

Increases:

• Functional residual capacity (FRC)
• Residual volume (RV)
• Forced Vital Capacity (FVC)

Question 17

How can obesity affect lung volume?

Answer 17

reduction in all static lung volumes (except tidal volume), especially ERV and functional residual capacity (FRC)

Question 18

Other than age, posture, and obesity, what other factors can influence lung volumes?

Answer 18

body size, sex, ethnicity, pulmonary disease