49: Ventilation

Question 1

P(a)

Answer 1

arterial partial pressure

Question 2

P(A)

Answer 2

alveolar partial pressure

Question 3

V(T)

Answer 3

tidal volume

Question 4

V(D)

Answer 4

dead space

Question 5

F(A)

Answer 5

fractional concentration alveolar

Question 6

F(E)

Answer 6

fractional concentration expired

Question 7

Henry’s Law

Answer 7

V(gas) = P(gas) x solubility

Question 8

Water vapor

Answer 8

Dry air is water saturated as it moves down respiratory trees to allow for proper gas exchange at alveoli

Question 9

Minute Ventilation

Answer 9

volume of air moved out of the lungs per minute

Question 10

Minute Ventilation Equation

Answer 10

V(E) = V(T) x f

V(T): ~500mL

V(E) = (0.5 L) x (12 breaths/min) –> 6L/min

Question 11

Anatomic dead space

Answer 11

trachea, bronchioles, respiratory tree

don’t contribute to gas exchange

150mL used up in dead space

Question 12

What is the best way to breath?

Answer 12

Less breaths, deeper breaths

Question 13

Alveolar Minute ventilation

Answer 13

the amount of ventilation that makes it to gas exchange site

V =(VTx f)–(VDx f)

Question 14

Functional Residual Capacity

Answer 14

lung not empty when inspire

FRC full of stale air

ventilation of fresh air must be enough to dilute stale air to create gas exchange

Question 15

Measuring Anatomic Dead Space

Answer 15

Inspire pure O2 and expire out

Measure until no longer pure O2 and Nitrogen is present

Usually 150mL

Question 16

Measure Alveolar Ventilation

Answer 16

Atmospheric CO2
is zero – all expired CO2 must come from a functional
alveolar unit

alveoli must be well perfused

Question 17

Physiological Dead Space

Answer 17

Anatomical Dead Space + Not well perfused alveolar (dead space)

Question 18

Bohr Method

Answer 18

Blood drawn to determine alveolar CO2 from arterial CO2 since they are the same

AND

Measure expired CO2

20-30% of tidal breath wasted on dead space

Question 19

V(D) / V(T)

Answer 19

((P(a)CO2 - P(E)CO2)) / P(a)CO2

Question 20

Constant Ventilation

Answer 20

allows maintenance of steady state (gas) b/n alveoli and capillary

PO2 = 100 mm Hg
PCO2 = 40 mm Hg

Question 21

Increased alveolar ventilation

Answer 21

Decrease PCO2

blow out more CO2

increase PO2

Question 22

Alveolar Gas Equation

** IMPORTANT

Answer 22

calculate global alveolar partial pressure of oxygen

P(Alveolus)O2 = P(Inspire)O2 - (P(Alveolus)CO2 / R))

Question 23

What happens to arterial pH during increased ventilation?

Answer 23

pH increases b/c less CO2 in blood

Question 24

Ventilation during exercise

Answer 24

normal metabolic changes:

Hyperpnea

increased ventilation
and cardiac output

arterial gas partial
pressures remain stable, venous CO2 rises

Question 25

Hyper/Hypo Ventilation changes

Answer 25

pathological changes:

pH increases

PCO2 decreases

Alveolar PO2 increases

Question 26

Lung Complaince

Answer 26

upper part: low compliance

lower part: high compliance

Question 27

Hypoventilation

Answer 27

decreased alveolar ventilation with increased PaCO2

Question 28

Hyperventilation

Answer 28

increased alveolar ventilation with decreased PaCO2

Question 29

Hypercapnia

Answer 29

increased carbon dioxide in blood

Question 30

Eupnea

Answer 30

well breath

Question 31

Hypopnea

Answer 31

decreased ventilation in response to lowered metabolic CO2

production

Question 32

Hyperpnea

Answer 32

increased ventilation in response to increased metabolic
CO2 production (e.g. exercise) – increased ventilation should purge CO2

Question 33

Tachypnea

Answer 33

(‘swift’ breath) increased frequency of breathing.

Ventilation may or may not change depending on tidal volume

Question 34

Dyspnea

Answer 34

(‘ill’ breath) shortness of breath / labored breathing

Question 35

Apnea

Answer 35

temporary cessation of breathing