Lecture 23 Pulmonary Circulation

Question 1

what are the two circulations of the lung?

Answer 1

1. high pressure/low flow

2. low pressure/high flow

Question 2

describe high pressure/low flow

Answer 2

thoracic aorta -> bronchial arteries -> trachea, bronchial tree, adventitia, CT

Question 3

describe low pressure/high flow

Answer 3

pulmonary artery/branches -> alveoli

Question 4

why do pulmonary arteries have more compliance?

Answer 4

they have 1/3 the wall thickness of the aorta

therefore can accommodate the stroke value of the right ventricle

Question 5

which agents constrict pulmonary arterioles

Answer 5

norepinephrine
epinephrine
angiotensin II
some prostaglandins

Question 6

which agents dilate pulmonary arterioles

Answer 6

isoproterenol

acetylcholine

Question 7

what agents constrict pulmonary venules?

Answer 7

serotonin
histamine
E. coli endotoxin

Question 8

what is the avg mean pulmonary arterial pressure(in mm Hg)

Answer 8

15

Question 9

what is the avg left atrium pressure (diastole) in mm Hg?

Answer 9

8

Question 10

effect of heavy exercise on blood flow thru lungs

Answer 10

flow thru lungs increase 4x to 7x

causes:
increase number of capillaries 3x
distends capillaries
increases flow rate 2x

Question 11

why is it that despite an increase in blood flow through lungs during exercise, there is only a minimal rise in pulmonary arterial pressure

Answer 11

the increased number of capillaries and flow rate causes blood to be moved through quick enough to cause a mild/no change in the PAP

Question 12

3 zones of blood flow

Answer 12

1: no blood flow, local alveolar capillary pressure never rises higher than alveolar air pressure
2: intermittent blood flow
3: continuous blood flow

Question 13

where can we find zone 2 blood flow? zone 3?

Answer 13

apices

lower areas of lings

Question 14

what effect does exercise have on distribution of blood through lung zones

Answer 14

converts the apices from zone 2 flow to zone 3 flow

Question 15

effect of left sided heart failure on left atrial pressure

Answer 15

blood dams up causing left atrial pressure to rise from 1-5 mmHg to 40-50 mmHg

Question 16

common causes of pulmonary edema

Answer 16

left sided heart failure
mitral valve disease
damage to capillary membranes (via infection or inspiration of noxious substances)

Question 17

what capillary pressure puts a patient at risk for pulmonary edema?

Answer 17

30 mm Hg

Question 18

forces (and values) that are included when calculating outward forces of capillaries

Answer 18

hydrostatic pressure (7)
interstitial fluid osmotic pressure (14)
interstitial fluid hydrostatic pressure (8)

Total Outward F = 29

Question 19

forces (and values) included when calculating inward forces of capillaries

Answer 19

capillary osmotic pressure (28)

total inward f = 28

Question 20

avg value for mean filtration pressure

Answer 20

1 mm Hg

Question 21

hypoxia

Answer 21

reduction in O2 content/partial pressure

increases the pressure in the pulmonary artery

Question 22

results of bronchial obstruction

Answer 22

constriction of blood vessels supplying poorly ventilated areas (lowers local alveolar PO2)

Question 23

a decrease in pH during bronchial obstruction is caused by

Answer 23

accumulation of CO2

causes vasoconstriction in pulmonary vessels

causes vasodilation sin other tissues

Question 24

results of hypoxia and bronchial obstruction

Answer 24

reduction of blood flow to portion of lung

decreases alveolar pCO2 = constriction of bronchi supplying that part of the long

Question 25

what is the avg pulmonary arterial pressure (in mm Hg)?

Answer 25

24/9 mm Hg

Question 26

what percentage of blood volume is in the lungs

Answer 26

9%