Pulmonary blood flow: Karius Lecture

Question 1

alveolar capillaries arise from

Answer 1

arise from the right ventricle

Question 2

alveolar capillaries: function

Answer 2

exchange CO2 and O2

Question 3

Extra-alveolar capillaries arise from the

Answer 3

left ventricle

Question 4

Extra alveolar capillaries: function

Answer 4

deliver oxygen and CO2 to the tissues of the lungs

Question 5

Extra alveolar capillaries: route

Answer 5

return to the heart in the pulmonary veins via the “venous admixture”

just means they dump their load into the venous system

Question 6

what is the outcome of venous admixture?

Answer 6

by returning oxygenate blood from the lung via the pulmonary veins, the partial pressure of the arterial oxygen reduces the arterial blood O2 by a few mmHg

also increases PCO2 of the arteries

Question 7

Alveolar Capillary vs Extra-alveolar capillary

PaO2 content

Answer 7

Alveolar Cap: low

Extra-Alveolar Cap: high

Question 8

Alveolar Capillary vs Extra-alveolar capillary

PaCO2

Answer 8

Alveolar Cap: high

Extra-Alveolar Cap: low

Question 9

Alveolar Capillary vs Extra-alveolar capillary

Function

Answer 9

Alveolar Cap: gas exchange

Extra-Alveolar Cap: provides nutrients/removes waste from the tissues of the lungs

Question 10

Alveolar Capillary vs Extra-alveolar capillary

Return to the heart

Answer 10

Alveolar cap: pulmonary vein

extra alveolar cap: pulmonary vein

Question 11

Alveolar Capillary vs Extra-alveolar capillary

blood gases ratio

Answer 11

Alveolar capillary: High PaO2/Low PaCO2

Extra Alveolar capillary: Low PaCO2/High PaCO2

Question 12

We were reminded that BP = CO x TPR. How does this apply to respiration?

Answer 12

we can substitute TPR with pulmonary vascular resistance

Question 13

Pulmonary vascular resistance must be about ____ of the systemic

Answer 13

1/4

Question 14

Pulmonary vascular resistance is determined by

Answer 14

high number of capillaries
how many are open at a given moment of time (it is perfectly normal not to be using all your lungs at rest

much less sympathetic tone/vasoconstricting forces

Question 15

what is a major stimulus that causes pulmonary vascular resistance?

Answer 15

hypoxia

Question 16

what is the role of the vasoconstriction produced by hypoxia?

Answer 16

increases blood flow to areas of the lung with good oxygen

Question 17

Does PVR increase or decrease during exercise?

Answer 17

decreases: more pulmonary capillaries open up to accommodate greater CO

Question 18

The role of volume in pulmonary vascular resistance

Answer 18

at very high or very low volumes, pulmonary resistance increases because the “stretch” of the capillaries ends up compressing them

think about it like a rubberband: when stretched, it gets thinner: diameter decreases in the capillary just like the rubberband

Question 19

Pulmonary vascular resistance vs system resistance

normal value

Answer 19

PVR: low
SR: moderate

Question 20

Pulmonary vascular resistance vs system resistance

Major constrictor

Answer 20

PVR: hypoxia
SR: sympathetics

Question 21

Pulmonary vascular resistance vs system resistance

how they change with exercise

Answer 21

PVR: decrease
SR: decrease

Question 22

Pulmonary vascular resistance vs system resistance

major control

Answer 22

PVR: local
SR: ANS

Question 23

At the APEX of the lungs

what’s what

Answer 23

Alveolar gas pressure is > than arterial gas pressure, which is > Venous gas pressure

PA > Pa> Pv

Question 24

in the MIDDLe of the lung

what’s what

Answer 24

Pa > PA > Pv

Question 25

in the BASE of the lung what's what

Answer 25

Pa > Pv > PA why? because we are below the level of the heart, and alveoli are smaller. here, blood flow is greatest?

Question 26

where is blood flow greatest in the lung?

Answer 26

the base: smaller alveolar, located below the heart. if you are below the heart, hydrostatic pressure increases

Question 27

where is blood pressure the least in the lung?

Answer 27

in the apex, which is a little bit above the heart. no gravity to produce hydrostatic pressure alveoli are somewhat expanded, and the blood flow is less

Question 28

where in the lung is blood flow "normal"

Answer 28

the middle part: because it is level with the heart. + alveoli are avrage sized

Question 29

what is "regional" blood flow in the lung determine by?

Answer 29

determine by how much gravity is working on the blood and how much air is in that region of the lung

Question 30

Apex

Answer 30

high alveolar pressure, low blood pressure, little blood

Question 31

middle

Answer 31

normal pressure on both sides, normal blood flow/pressure, normal blood amount

Question 32

base

Answer 32

relatively low alveolar pressure, relatively high blood pressure, lots of blood

Question 33

NO

Answer 33

made by endothelium causes smooth muscle relaxation+vasodilation significant role in normal pulmonary blood flow

Question 34

Endothelin 1

Answer 34

also made in lungs vasoconstrictor not a player under normal conditions: mainly a pathologic player

Question 35

Thromboxane A2

Answer 35

same as Endothelin 1: vasoconstrictor that can be found in the pulmonary vasculature under the wrong conditions

Question 36

how are the lungs kept "dry" ?

Answer 36

the right balance of sterling forces