L23: Pulmonary Circulation & Gas Exchange

Question 1

high pressure - low flow

Answer 1

thoracic aorta –> bronchial arteries —>

trachea, bronchial tree, adventitia CT

Question 2

low pressure - high flow

Answer 2

pulmonary artery and branches —> alveoli

Question 3

what are the two circulations of the lung

Answer 3

high pressure; low flow

low pressure; high flow

Question 4

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

Answer 4

the pulmonary arterial tree has higher compliance

allowing pulmonary arteries to accommodate SV output of right ventricle

Question 5

how much blood is w/in pulmonary circulation

Answer 5

450 ml

9%

Question 6

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

Answer 6

pressure

increases blood vol by 100% and increased bp

Question 7

normal pulmonary arterial pressure =

Answer 7

24/9 mmhg

Question 8

mean pulmonary arterial pressure =

Answer 8

15

Question 9

left atrium pressure =

Answer 9

8

mean lap = 2

Question 10

pressure gradient in pulmonary system =

Answer 10

7 mmhg

Question 11

agents that constrict pulmonary arterioles

Answer 11

norepinephrine
angiotensin II
prostaglandins

Question 12

agents that dilate pulmonary arterioles

Answer 12

isoproterenol

ACH

Question 13

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

Answer 13

top gets little

bottom get 5x

Question 14

agents that constrict pulmonary venules

Answer 14

serotonin
histamines
e coli endotoxin

Question 15

effect of heavy exercise on blood flow thru lungs

Answer 15

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

Question 16

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

Answer 16

increase very little even during max exercise

Question 17

what is physiologic shunt in the lungs

Answer 17

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

Question 18

what are the 3 zones of blood flow in the lungs

Answer 18

1. no flow
2. intermittent flow
3. continuous flow

Question 19

relate the 3 zones of blood flow to specific lung areas

Answer 19

top = zone 2

middle, lower = z3

Question 20

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

Answer 20

converts top lungs from z2 to z3

Question 21

pulmonary capillary pressure =

Answer 21

7 mmhg

Question 22

peripheral tissue capillary pressure =

Answer 22

17 mmhg

Question 23

interstitial fluid pressure in lungs is more _____ than peripheral is

Answer 23

more negative

Question 24

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

Answer 24

proteins
= 14
peripheral <7

Question 25

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

Answer 25

positive press. | interstitial spaces

Question 26

capillaries --> pulmonary interstitium total outward force total inward force into capillaries

Answer 26

out = 29 in = 28

Question 27

mean filtration pressure =

Answer 27

29 - 28 = 1 mmhg

Question 28

excess fluid in the lungs is carried away by

Answer 28

lymphatics

Question 29

left atrial pressure is normally never above

Answer 29

+6 mmhg

Question 30

in left heart failure, left atrial pressure rises to ?

Answer 30

40-50 mmhg normal = 6

Question 31

left atrial pressure above 8 =

Answer 31

causes equal increases in pulmonary arterial pressure

Question 32

left atrial pressure above 30 =

Answer 32

pulmonary edema

Question 33

pulmonary edema occurs when pulmonary capillary pressure

Answer 33

greater than 25

Question 34

most common causes of pulmonary edema

Answer 34

left side failure mitral valve disease damage to lung capillaries

Question 35

pleural effusion

Answer 35

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

Question 36

pleural effusion is edema of the

Answer 36

pleural cavity

Question 37

hypoxia increases pressure in the

Answer 37

pulmonary artery

Question 38

declines in pH produce _____ of other tissues

Answer 38

vasodilation

Question 39

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

Answer 39

--constriction of vessels supply afflicted alveoli --reduction of blood flow to that portion of lung

Question 40

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

Answer 40

- -rate of O2 absorption into blood | - -rate of new o2 entry into lungs

Question 41

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

Answer 41

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

Question 42

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

Answer 42

rate of co2 excretion alveolar ventilation

Question 43

rate of co2 excretion

Answer 43

alveolar pCO2 increases in direct proportion to rate of excretion

Question 44

alveolar pCO2 is _____ related to alveolar ventilation

Answer 44

inversely

Question 45

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

Answer 45

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

Question 46

Va/Q ratio is the

Answer 46

ventilation-perfusion ratio = alveolar ventilation/blood flow

Question 47

normal Va/Q ratio =

Answer 47

0.8 ``` pulmonary = 5 L/min ventilation = 4 L/min ```

Question 48

Va/Q = 0 when

Answer 48

Va = 0 | but there is still perfusion

Question 49

Va/Q = infinite when

Answer 49

Q = 0 | but there is still ventilation but no gas is exchanged

Question 50

alveoli partial pressures for normal vs. ventilation obstructions

Answer 50

po2 = 149 pco2 = 0 for obstructions normal po2 = 104 pco2 = 40

Question 51

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

Answer 51

passing thru pulmonary capillaries does not become oxygenated

Question 52

the greater the physiologic shunt the greater

Answer 52

the amount of blood that fails to be oxygenated

Question 53

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

Answer 53

there is more o2 in alveoli than can be transported in blood thus ventilation of these alveoli is wasted