DSA - Lung Volumes & Capacities

Question 1

The goal of respiration is to get air from the mouth/nose to the ________.

Answer 1

Alveolus

Question 2

What is the physiologic unit of the lung?

Answer 2

Alveolar-Capillary Unit

Question 3

This is the amount of air inspired or expired in a single breath.

Answer 3

Tidal Volume (VT)

Question 4

Tidal Volume varies under circumstances, for example it (INCREASES/DECREASES) during aerobic exercise.

Answer 4

Increases

Question 5

Normal resting Tidal Volume is ________.

Answer 5

500 ml

Question 6

This is the volume of air that cannot be forced out, not matter how hard one tries.

Answer 6

Residual Volume (RV)

Question 7

When you get the wind knocked out of you, that means you were forced into ________ ________.

Answer 7

Residual Volume

Question 8

Residual Volume cannot be determined by…

Answer 8

Spirometry

Question 9

This is the additional volume that can be inhaled greater than the Tidal Volume. Considered the gap between inspiration during Tidal Volume and maximal inspiration.

Answer 9

Inspiratory Reserve Volume (IRV)

Question 10

This is the additional volume that can be exhaled greater than Tidal Volume. This does NOT include Residual Volume.

Answer 10

Expiratory Reserve Volume (ERV)

Question 11

Expiratory Reserve Volume requires activation of _________ _________ (i.e., active respiration).

Answer 11

Expiratory Muscles

Question 12

This is the maximal volume to which lungs can be expanded with greatest effort. This cannot be measured by spirometry.

Answer 12

Total Lung Capacity (TLC)

Question 13

What are the 3 possible equations for Total Lung Capacity?

Answer 13

TLC = IC + FRC

TLC = VC + RV

TLC = ERV + RV + IRV + VT

Question 14

This is the amount of air that remains in the lungs following a normal expiration. This cannot be measured by spirometry.

Answer 14

Functional Residual Capacity (FRC)

Question 15

What is the equation for Functional Residual Capacity?

Answer 15

FRC = ERV + RV

Question 16

This helps prevent collapse of lungs, reduces workload, and dilutes toxic inhaled gases.

Answer 16

Functional Residual Capacity

Question 17

This is the amount of air that can be maximally inspired following a maximal expiration.

Answer 17

Vital Capacity (VC)

Question 18

What is the equation for Vital Capacity?

Answer 18

VC = IRV + VT + ERV

Question 19

This is influenced by posture, ability of diaphragm to contract/relax, strength of respiratory muscles, thoracic wall expansibility, resistance to air flow, lung elasticity, and disease.

Answer 19

Vital Capacity

Question 20

This is the capacity of air that can be maximally inspired following a normal exhale.

Answer 20

Inspiratory Exhale (IC)

Question 21

What is the equation for Inspiratory Capacity?

Answer 21

IC = VT + IRV

Question 22

What are the main influences on lung volumes?

Answer 22

Body size
Age
Posture
Sex
Ethnicity 
Obesity 
Other pulmonary disease

Question 23

What increases or decreases with age?

Answer 23

Decreases = Forced Vital Capacity (FVC)
Increases = Functional Residual Capacity (FRC) 
Increases = Residual Volume (RV)

Question 24

Posture causes a reduced ________ when supine.

Answer 24

FRC (Functional Residual Capacity)

Question 25

With the exception of _______ ______, obesity causes a reduction in all static lung volumes, particularly ________ ________ ________, and so ________.

Answer 25

Tidal Volume (VT)
Expiratory Reserve Volume (ERV)
FRC (Functional Residual Capacity)

Question 26

How can Residual Volume be measured?

Answer 26

Helium (He) Dilution

Question 27

Describe how the Helium Dilution test works for Residual Volume.

Answer 27

You inhale a known concentration (C1) of Helium, which is insoluble in blood, from a known volume (V1). The change in concentration (C2) due to the inhalation allows us to determine V2, which is equal to FRC.

Question 28

Describe the Body Plethysmography test for Residual Volume.

Answer 28

You are enclosed in a rigid box and breath against a shutter. The pressure in the lungs change, and the pressure in the box changes proportionally in the opposite direction. This is calculated via Boyle’s Law (P1V1 = P2V2).

Question 29

Describe the Nitrogen-Washout Technique for Residual Volume.

Answer 29

It determines FRC. The individual breaths 100% O2 through a one-way valve, and all expired gas is collected and monitored until N2 reaches zero. Total volume of all gas expired is determined, and multiplied by % of N2 in mixed expired air (80%).