Respiration Lecture 06: Ventilation, Work and Breathing Strategies

Question 0

alveolar ventilation

Answer 0

how pumping actions affect PO2 and PCO2 in the alveolus

Question 1

ventilation

Answer 1

process by which the concentrations of O2 and CO2 are established

Question 2

minute ventilation =

Answer 2

breathing frequency X tidal volume. The amount of gas moved into and out of lung over time (L/min)

Question 3

2 major divisions of the lung

Answer 3

1) gas exchange area (respiratory zone)

2) gas conducting zone

Question 4

Which divisions of lung are ventilated and which participate in gas exchange?

Answer 4

Both ventilated; only respiratory zone part. in gas exchange

Question 5

VO2

Answer 5

rate that O2 is removed from the alveolus

Question 6

VCO2

Answer 6

rate CO2 is released into alveolus

Question 7

concentrations of alveolar gases compared to air

Answer 7

lower O2, higher CO2 than air

Question 8

Dead space volume (VD)

Answer 8

volume of air in conducting zone. Considered “wasted ventilation”

Question 9

Vt = what two volumes?

Answer 9

VD + VA (dead space volume + alveolar volume)

Question 10

Alveolar ventilation (V’A)

Answer 10

portion of the minute ventilation that is involved directly in refreshing the alveolar gas. V’A = VA * f . Directly related to concentrations of O2 and CO2 in the blood.

Question 11

Increased VD for same Vt –> V’A?

Answer 11

Decrease

Question 12

Most effective way to increase V’A?

Answer 12

Increase Vt and keep VD constant

Question 13

What does “arterial” refer to?

Answer 13

blood coming into L heart that’s been through the lung and participated in gas exchange

Question 14

What is rate at which CO2 is removed from the lung a fx of?

Answer 14

V’A and V’CO2

Question 15

Increased V’CO2 –> PACO2?

Answer 15

increases

Question 16

Increased V’A –> PACO2?

Answer 16

Decreases

Question 17

Review graph on page 37

Answer 17

:)

Question 18

Effect of FRC on oscillation of PCO2 and PO2

Answer 18

Decreased FRC leads to more rapid oscillations. FRC helps to stabilize O2 and CO2 concentrations over the total breathe

Question 19

What is the maximum level PAO2 can reach?

Answer 19

PiO2

Question 20

Hyperventilation

Answer 20

Breathing so much (increasing V’A) that alveolar PCO2 drops below 40mmHg

Question 21

Hypoventilation

Answer 21

Decreasing alveolar ventilation so that alveolar PCO2 increases above 40mmHg

Question 22

V’A indirectly effects ARTERIAL O2 and CO2

Answer 22

:)

Question 23

end-expiratory sample

Answer 23

measurement of the PO2 and PCO2 in the last gas to leave the mouth at the end of an expiration. Contains alveolar gas without non-exchanged dead space air.

Question 24

Work

Answer 24

moving mass over a distance

Question 25

respiratory work =

Answer 25

area under pressure-volume curve

Question 26

inspiratory work

Answer 26

deviation to the right of the straight line on P/V curve during inspiration necessary to overcome resistance

Question 27

expiratory work

Answer 27

deviation to the left of the line during expiration on P/V curve necessary to overcome resistance

Question 28

mechanical work

Answer 28

work used to overcome the lung elastic recoil during inspiration. Stored as potential energy and is recovered during expiration

Question 29

what is elastic work related to?

Answer 29

volume

Question 30

what is resistive work related to?

Answer 30

flow and changes in frequency

Question 31

Total work =

Answer 31

elastic work + resistive work

Question 32

How do most animals minimize work for breathing?

Answer 32

adjust BOTH Vt and f to minimize work and optimize V’A

Question 33

What requires more work, increasing f or increasing Vt? Which produces greatest change in V’A?

Answer 33

increasing Vt. Increasing Vt has greatest effect on increasing V’A

Question 34

horse breathing strategy

Answer 34

splits Vt above and below FRC to avoid large active inspiratory volumes and decrease amt. of elastic muscle work needed. Have stiff chests. Also uses gait to assist breathing by inspiring during swing phase and expiring during forelimb strike.