perfusion and ventilation

Question 1

size of respiratory zone of lung

Answer 1

50-100m

Question 2

perfusion def

Answer 2

flow of blood through lung

Question 3

air blood barrier contains

Answer 3

alveolar epithelium (squamous), capillary endothelium, basement membrane (.5microm thick.. gas can diffuse)

Question 4

pulm blood flow

Answer 4

same flow as systemic circulation (5L/min) but low R!

Question 5

how long does blood travel through lung at rest.

Answer 5

4-5 sec, 75 ml at once

Question 6

factors that affect perfusion (5)

Answer 6

compliance, change in transmural P of alveolar P, lung volume, hypoxic vasoconstriction, gravity

Question 7

complaince

Answer 7

thin wall, low SM increases compliance. Accept large volume, pulsitile, lower pulse pressure

Question 8

compliance features

Answer 8

recruitment and distention

Question 9

recruitment

Answer 9

collapsed vessels open with pressure

Question 10

distention

Answer 10

capillary increase radi (allow more blood flow)

Question 11

change in transmural P of alv.

Answer 11

Ptm=Piv-Pa, sometimes they cancel (cardiac vs resp cycle)

Question 12

lung volume and PERFUSION

Answer 12

alv vessels : compress at high volume. extra all: open at high volume, lowest overall P during inspiration.

Question 13

hypoxic vasoconstriction

Answer 13

PAoz<60, pulm vessels constrict (OPP OF SYSTEMIC), local affects, divert flow from poor ventilation

Question 14

gravity

Answer 14

highest blood flow is in base of lung (apex stretched, less compliance)

Question 15

pulm capillary fluid dynamics

Answer 15

fluid leaves cap>interstitium, 3 possible routes

Question 16

where can fluid go from interstitium?

Answer 16

vaporized, reabsorbed in venule, lymphatics

Question 17

ventilation def

Answer 17

transport of gas to alveolar surface

Question 18

minute ventilation

Answer 18

RR * TV (12*500=6000)

Question 19

alveolar ventilation

Answer 19

VA=RRx (TV-deadspace)=12*350=4200

Question 20

PACO2=

Answer 20

VCO2/VA