DSA: Lung Volume & Capacities

Question 1

what is the physiological unit of the lung

Answer 1

alveolar-capillary unit

Question 2

how does blood from the left heart get to the lungs

-what is its fxn

Answer 2

bronchial A

oxygenated blood to nourish the lungs

Question 3

what is VT

Answer 3

Tidal Volume

• amount of air inspired/expired in a single breath
• normal = 500 mL

Question 4

what is RV

Answer 4

Residual Volume

= volume of air that cannot be forced out, no matter how hard you try

(1200 mL)

Question 5

What is IRV

Answer 5

Inspiratory Reserve Vol

-volume that can be inhaled greater than tidal volume

(measure from V_T to max inspiration volume)

(3000 mL)

Question 6

What is ERV

Answer 6

Expiratory Reserve Vol

-volume that can be exhaled greater than tidal vol

(doesn’t include RV)

(1100-1200 mL)

Question 7

what is required to achieve ERV

Answer 7

activation of expiratory Ms

Question 8

What is TLC

& how do you calculate it

Answer 8

maximal volume that lungs can be expanded w/ greatest effort

= IC + FRC

=VC + RV

= ERV + RV + IRV + V_T

(5800-6000 mL)

Question 9

what is FRC

Answer 9

Functional Residual Capacity

air that remains in lungs after normal expiration

= ERV + RV

(2300-2400 mL)

Question 10

what is the fxn of FRC

Answer 10

prevent collapse of lungs, reduce workload & dilute toxic inhaled gases

Question 11

What is VC

Answer 11

vital capacity

• volume maximal inspired after maximal expiration

= IRV + ERV + V_T

Question 12

what can influence VC

Answer 12

posture

ability of diaphragm to contract/relax

strength of resp Ms

thoracic wall ability to expand

resistance to air flow

lung elasticity

disease

Question 13

What is IC

Answer 13

Inspiratory capacity

= air that can be maximally inspired after normal exhale

=IRV + V_T

Question 14

what is normal V_T

Answer 14

500 mL

Question 15

what increases with age

Answer 15

FRC and RV

*FVC decreases*

Question 16

What happens to FRC when supine

Answer 16

reduced

Question 17

what does obesity cause

Answer 17

reduction of all static lung vols (except V_T)

particularly ERV and FRC

Question 18

what can influence lung vol

Answer 18

1. Body size
2. Age
3. Sex
4. Ethnicity
5. Disease
6. Obesity
7. Posture

BASED OP

Question 19

How do you calculate FRC

Answer 19

Question 20

What is boyle’s law

What test do you use this equation

Answer 20

P₁V₁ = P₂V₂

Body plethysmography - pt in box and diff in pressure measured

Question 21

How is residual volume measured

Answer 21

1. He dilution
2. Body plethysmography
3. Nitrogen-washout Technique

Question 22

which Ms are used in inspiration

Answer 22

diaphragm & external intercostal

Question 23

What Ms are involved in expiration

Answer 23

internal intercostal M