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Physiology Exam 3 > L23: Pulmonary Circulation & Gas Exchange > Flashcards

L23: Pulmonary Circulation & Gas Exchange Flashcards

1
Q

high pressure - low flow

A

thoracic aorta –> bronchial arteries —>

trachea, bronchial tree, adventitia CT

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2
Q

low pressure - high flow

A

pulmonary artery and branches —> alveoli

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3
Q

what are the two circulations of the lung

A

high pressure; low flow

low pressure; high flow

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4
Q

the wall thickness of the pulmonary artery is 1/3 that of the aorta, thus

A

the pulmonary arterial tree has higher compliance

allowing pulmonary arteries to accommodate SV output of right ventricle

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5
Q

how much blood is w/in pulmonary circulation

A

450 ml

9%

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6
Q

failure of left side of heart causes _____ to build in pulmonary circulation

A

pressure

increases blood vol by 100% and increased bp

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7
Q

normal pulmonary arterial pressure =

A

24/9 mmhg

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8
Q

mean pulmonary arterial pressure =

A

15

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9
Q

left atrium pressure =

A

8

mean lap = 2

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10
Q

pressure gradient in pulmonary system =

A

7 mmhg

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11
Q

agents that constrict pulmonary arterioles

A

norepinephrine
angiotensin II
prostaglandins

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12
Q

agents that dilate pulmonary arterioles

A

isoproterenol

ACH

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13
Q

when standing, little blood flow goes to the ____ of the lungs, whilst the _____ of the lungs gets 5x as much

A

top gets little

bottom get 5x

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14
Q

agents that constrict pulmonary venules

A

serotonin
histamines
e coli endotoxin

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15
Q

effect of heavy exercise on blood flow thru lungs

A
  • -flow increases 4-7x
  • -increase # of open capillaries by 3x
  • -increase pulmonary arterial pressure
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16
Q

because of all the pulmonary compensations during exercise, arterial pressure will ?

A

increase very little even during max exercise

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17
Q

what is physiologic shunt in the lungs

A

2% of blood in systemic arteries is blood that has bypassed the pulmonary capillaries

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18
Q

what are the 3 zones of blood flow in the lungs

A
  1. no flow
  2. intermittent flow
  3. continuous flow
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19
Q

relate the 3 zones of blood flow to specific lung areas

A

top = zone 2

middle, lower = z3

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20
Q

what effect does exercise have on blood flow zones to lungs?

A

converts top lungs from z2 to z3

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21
Q

pulmonary capillary pressure =

A

7 mmhg

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22
Q

peripheral tissue capillary pressure =

A

17 mmhg

23
Q

interstitial fluid pressure in lungs is more _____ than peripheral is

A

more negative

24
Q

pulmonary capillaries are leaky to _____ molecules because colloid osmotic pressure = ____. when peripheral = ?

A

proteins
= 14
peripheral <7

25
Q

alveolar walls can be ruptured by any ____ pressure in the ______ _____ greater than alveolar air pressure

A

positive press.

interstitial spaces

26
Q

capillaries –> pulmonary interstitium
total outward force

total inward force into capillaries

A

out = 29

in = 28

27
Q

mean filtration pressure =

A

29 - 28 = 1 mmhg

28
Q

excess fluid in the lungs is carried away by

A

lymphatics

29
Q

left atrial pressure is normally never above

A

+6 mmhg

30
Q

in left heart failure, left atrial pressure rises to ?

A

40-50 mmhg

normal = 6

31
Q

left atrial pressure above 8 =

A

causes equal increases in pulmonary arterial pressure

32
Q

left atrial pressure above 30 =

A

pulmonary edema

33
Q

pulmonary edema occurs when pulmonary capillary pressure

A

greater than 25

34
Q

most common causes of pulmonary edema

A

left side failure
mitral valve disease
damage to lung capillaries

35
Q

pleural effusion

A

pumping of fluid from pleural space by the lymphatics creates a normal pressure in pleural space = -7

36
Q

pleural effusion is edema of the

A

pleural cavity

37
Q

hypoxia increases pressure in the

A

pulmonary artery

38
Q

declines in pH produce _____ of other tissues

A

vasodilation

39
Q

what are the results of bronchial obstruction or hypoxia on blood flow?

A

–constriction of vessels supply afflicted alveoli

–reduction of blood flow to that portion of lung

40
Q

what are the factors that control oxygen conc. in the alveoli

A
  • -rate of O2 absorption into blood

- -rate of new o2 entry into lungs

41
Q

why alveolar ventilation cannot increase pO2 above 149 under normal circumstances?

A

because 149 mmhg is the max pCO2 in humidified air at normal atm air at sea level

42
Q

what are the factors that control CO2 conc. in the alveoli?

A

rate of co2 excretion

alveolar ventilation

43
Q

rate of co2 excretion

A

alveolar pCO2 increases in direct proportion to rate of excretion

44
Q

alveolar pCO2 is _____ related to alveolar ventilation

A

inversely

45
Q

list factors that determine how rapidly a gas will pass thru the respiratory membrane

A

memb. thickness
memb. surface area
diffusion coefficient of gas
partial pressure difference of gas

46
Q

Va/Q ratio is the

A

ventilation-perfusion ratio

= alveolar ventilation/blood flow

47
Q

normal Va/Q ratio =

A

0.8

pulmonary = 5 L/min
ventilation = 4 L/min
48
Q

Va/Q = 0 when

A

Va = 0

but there is still perfusion

49
Q

Va/Q = infinite when

A

Q = 0

but there is still ventilation but no gas is exchanged

50
Q

alveoli partial pressures for normal vs. ventilation obstructions

A

po2 = 149
pco2 = 0
for obstructions

normal
po2 = 104
pco2 = 40

51
Q

shunted blood - when Va/Q is below normal a fraction of venous blood

A

passing thru pulmonary capillaries does not become oxygenated

52
Q

the greater the physiologic shunt the greater

A

the amount of blood that fails to be oxygenated

53
Q

when ventilation of alveoli is great but alveolar blood flow is low ?

A

there is more o2 in alveoli than can be transported in blood

thus ventilation of these alveoli is wasted

Physiology Exam 3 (10 decks)

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