lect 23- Pulmonary circulation Flashcards Preview

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Flashcards in lect 23- Pulmonary circulation Deck (36):
1

what is the circulation for high pressure, low flow

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

2

what is the circulation for low pressure, high flow

pulmonary artery and branches--> alveoli

3

what is the value for the pulmonary arterial pressure

24/9 mm Hg

4

what is the value for mean pulmonary arterial pressure

15 mm Hg

5

what is the pressure gradient in pulmonary system

7 mm Hg

6

what is the mean pressure in the left atrium

2 mm Hg

7

what happens to pulmonary circulation if there is a failure in the life side of the heart

increases blood volume as much as 100%
increases blood pressure
mild systemic effect because systemic blood volume is 9 times that of the pulmonary system

8

what is "dirty blood"

blood coming from the lung parenchyma and life side of the heart (it bypasses the pulmonary capillaries)

9

what happens when oxygen concentration in alveoli is 70& or more below normal

adjacent blood vessels constrict
caused by unknown vasoconstrictor that is possibly released by alveolar epithelial cells

10

describe zone 1 of the lungs

no blood flow; local alveolar cap. pressure never rises higher than alveolar air pressure

11

describe zone 2 of the lungs

intermittent blood flow (only during systole)

12

describe zone 3 of the lungs

continuous blood flow

13

how is blood flow normally distributed into the zones

apices have zone 2 flow
lower areas have zone 3 flow

14

what happens to the zones in the lungs during exercise

convert apices from zone 2 to zone 3 flow

15

what leads to general circulation when a person stands up

the fact that the pulmonary veins are a blood reservoir, increasing pulmonary blood volume by up to 400 ml

16

what results from obstructing blood supply to one normal lung

blood flow through other lung is doubled
because of passive dilation of pulmonary vessels, the pulmonary pressure in the other lung is only slightly increased

17

what agents constrict pulmonary arterioles

norepinephrine
epinephrine
angiotensin II
some prostaglandins

18

what agents dilate pulmonary arterioles

isoproterenol
acetylcholine

19

what agents constrict pulmonary venules

serotonin
histamine
E. coli endotoxin

20

what does sympathetic vasoconstrictor nerve fibers do

outflow from cervical sympathetic ganglia
decrease pulmonary blood flow by as much as 30%
mobilize blood from pulmonary reserve

21

what happens to blood from through the lungs during exercse

it increases 4X to 7X
number of open capillaries increases up to 3X
distends all capillaries and increases flow rate up to 2X
increase in pulmonary arterial pressure

22

why is it important that pulmonary arterial pressure rises little even during max exercise

it conserves energy of right side of heart
prevents significant rise in pulmonary capillary pressure

23

what happens during left heart failure

blood begins to dam up in left atrium
left atrial pressure rises from 1-5 mm Hg to 40-50 mm Hg

24

when is pulmonary edema likely to occur

when left atrial pressure rises above 25-30 mm Hg

25

how does colloid osmotic pressure in pulmonary interstitial tissue compare to that in peripheral tissue

in pulmonary interstitial tissues it is about 2X as high

26

how is alveolar epithelium ruptured

by any positive pressure in the interstitial spaces greater than alveolar air pressure

27

what is the total outward force for capillaries (pulmonary interstitial forces)

29

28

what is the mean filtration pressure

28

29

how can excess fluid in the lung capillary be carried away

pulmonary lymphathics

30

what are the most common causes of pulmonary edema

left-sided heart failure or mitral valve disease
damage to pulmonary blood capillary membranes (infections, breathing noxious substances)

31

at what pressure will lungs usually collapse

-4 mm Hg

32

what is pleural effusion

edema of the pleural cavity

33

what are causes of pleural effusion

blockage of lymphathic drainage form pleural cavity
cardiac failure
considerably reduced plasma colloid osmotic pressure
infection/inflammation

34

what does hypoxia do to pulmonary arteries

increases the pressure in them, possibly because of the release of prostaglandin

35

what is the result of bronchial obstruction

constriction of vessels supplying the poorly ventilated alveoli

36

what does reduction of blood flow to a portion of the lung do to alveolar PCO2

lowers alveolar PCO2, resulting in a constriction of the bronchi supplying that portion of the lung