RS Lec 5

Question 1

pressure exerted by gas molecules due to

Answer 1

their motion, motion exerts pressure

Question 2

pressure increases as

Answer 2

temp increases, conc increases

Question 3

dalton’s law

Answer 3

total pressure= sum of individual pressures (partial pressures)

Question 4

diffusion

Answer 4

rate of transfer of gas through tissue/unit time

Question 5

diffusion is proportional to (3)

Answer 5

• tissue area
• difference is gas partial pressure
• diffusion constant

Question 6

diffusion is inversely proportional to (1)

Answer 6

-tissue thickness

Question 7

solubility of CO2 and O2

Answer 7

carbon dioxide solubility is much higher than O2 but have similar molecular weight, co2 diffuses 20x faster than o2

Question 8

Diffusion constant (D) proportional

Answer 8

-to solubility/ square root (molecular weight)

Question 9

henry’s law

Answer 9

-amount of gas dissolved in a liquid is directly proportional to partial pressure of gas in equilibrium

Question 10

concentration of gas (in liquid) =

Answer 10

pressure (only gas dissolved in liquid contributes to partial pressure) x solubility

Question 11

PO2 in air > PO2 in alveoli because (3)

Answer 11

• humidification of air in respiratory tract ↓
• loss of O2 to blood diffusion ↓
• mixing of inspired air with alveolar air (functional residual capacity) ↓

Question 12

what determines alveolar PO2? (4)

Answer 12

• PO2 in atmosphere
• alveolar ventilation (Va)
• metabolic rate
• perfusion

Question 13

what determines alveolar PCO2?

Answer 13

• PCO2 in atmosphere
• alveolar ventilation (Va)
• metabolic rate
• perfusion

Question 14

increasing alveolar ventilation will

Answer 14

• increase alveolar PO2

- decrease alveolar PCO2

Question 15

Increasing metabolic rate will

Answer 15

• decrease alveolar PO2

- increase alveolar PCO2

Question 16

partial pressure of gas in alveoli determine

Answer 16

-arterial levels,

Question 17

cardiac output

Answer 17

-volume of blood pumped by heart per minute (ml blood/min)

Question 18

systemic circulation

Answer 18

-high pressure system needed to deliver blood to body (high resistance system)

Question 19

pulmonary circulation

Answer 19

-low pressure system needed to deliver blood to lungs (high pressures= lung edema)

Question 20

systemic circulation and pulmonary circulation

Answer 20

flow systemic circulation = flow pulmonary circulation

Question 21

pulmonary low pressure system

Answer 21

-need to pump blood only to the top of the lung, important for avoiding rupture of resp. membran + edema formation

Question 22

pulmonary low resistance system

Answer 22

-R is less than 1/10 of that in the systemic circulation due to: shorter and wide vessels

Question 23

pulmonary high compliance vessels

Answer 23

• higher number of arterioles with low resting tone
• due to thin walls and paucity of smooth muscle, can accept large amount of blood
• can dilate in response to modest increases in arterial pressure

Question 24

pulomonary blood volume

Answer 24

450 ml

Question 25

capillary blood volume

Answer 25

70 ml at rest

200 ml during exercise

Question 26

time blood passes through pulmonary capillaries

Answer 26

• at rest: 0.75 s at rest

- cardiac output increases: 0.3 s

Question 27

if capillary pressyre falls below alv pressure

Answer 27

capillaries close off, diverting blood to other pulmonary capillary beds with higher pressures.

Question 28

air should be delivered to regions with

Answer 28

blood flow and vice versa

Question 29

ventilation/perfusion (V/Q) ratio

Answer 29

balance between lung ventilation/ lung perfusion

-affects alv. arterial levels of oxygen + carbon dioxide

Question 30

lung ventilation

Answer 30

O2 ATM –> alveoli/ CO2 alveoli –> ATM

Question 31

lung perfusion

Answer 31

O2 alveoli –> blood/CO2 blood –> alveoli

Question 32

Increase in ventilation

Answer 32

• PO2 + PCO2 in alveoli ≈ PO2 + PCO2 in ATM

Question 33

Increase in perfusion

Answer 33

• PO2 + PCO2 in alveoli ≈ PO2 + PCO2 in mixed-venous blood

Question 34

high V/Q ratio

Answer 34

-lack perfusion (alveolar dead space)- aire not reaching the blood

Question 35

low V/Q ratio

Answer 35

-lack ventilation (airway obstruction –> shunt)

Question 36

local V/Q ratio determines

Answer 36

-local alveolar PO2 + PCO2

Question 37

top of the lungs V/Q

Answer 37

• high V/Q

Question 38

ventilation is greatest

Answer 38

at bottom of the lung

Question 39

perfusion is greatest

Answer 39

at the bottom of the lung (depends on gravity and posture)

Question 40

V/Q is not

Answer 40

constant/uniform in healthy lung

Question 41

apical V/Q

Answer 41

3 x V/Q

Question 42

basal V/Q

Answer 42

0.6 x V/Q (closer to ideal)

Question 43

pulmonary hypoxic vasoconstriction

Answer 43

-response of pulmonary capillaries to low O2, diverts blood to oxygen rich alveoli

Question 44

local perfusion decrease to match local decrease in ventilation

Answer 44

↓ air flow= ↓ PO2 (alveoli) = vasoconstriction= ↓ blood flow

Question 45

local ventilation decrease to match local decrease in perfusion

Answer 45

↓ blood flow= ↓ PCO2 (alveoli) = bronchoconstriction = ↓ air flow