Pulmonary Blood flow

Question 1

Alveolar Capillaries

Answer 1

Arise from the right ventricle
• Are involved in the exchange of O2 and CO2 between
the blood and the air
• Millions of alveolar capillaries make is so the alveoli are
effectively a sheet of capillaries

Question 2

Extra-Alveolar Capillaries

Answer 2

Arise from the left ventricle
• Deliver oxygen and CO2 to the tissue of the lungs
• Return to the heart in the pulmonary veins (venous
admixture)
o Reduces the PaO2 of the arterial blood by a few mm Hg.
o Increases the PaCO2 to a small degree.

Question 3

PaO2 of alveolar capillary and extra alveolar capillary

Answer 3

aveolar- low

extra-alveolar-high

Question 4

PaCO2 of alveolar capillary and extra alveolar capillary

Answer 4

aveolar- high

extra-alveolar-low

Question 5

Function of alveolar capillary

Answer 5

Gas exchange

Question 6

function of extra-alveolar capillary

Answer 6

Provide nutrients/remove waste from the tissue of

the lungs

Question 7

blood gases alveolar capillary

Answer 7

High PaO2/Low PaCOw

Question 8

blood gases extra alveolar capillary

Answer 8

Low PaO2/High PaCO2

*venous admixture

Question 9

calculate pulmonary vascular resistance

Answer 9

PBP = COxPVR

Question 10

pulmonary vascular resistance relative to systemic

Answer 10

must be about ¼ of the systemic.

Question 11

How is Pulmonary vascular resistance determined

Answer 11

High number of capillaries
o How many are open at any given moment in time (it is
perfectly normal not to be using all your lungs at rest)
o Much less sympathetic tone/vasocontricting forces

Question 12

What is a major stimulus that causes an increase in
pulmonary vascular resistance?
• A. Activation of alpha-adrenergic receptors
• B. Inhibition of nicotinic receptors on the
vasculature.
• C. The presence of hypoxia in a region of the lung.
• D. An increase in sympathetic activation of the
adrenal medulla.

Answer 12

• C. The presence of hypoxia in a region of the lung.

Question 13

What is the major role of the vasoconstriction
produced by hypoxia?
• A. Direct the air to the parts of the lung getting the
most blood.
• B. Control the pulmonary blood pressure at normal
levels.
• C. Maintain blood flow to deliver oxygen to the
bronchi
• D. Increase blood flow to areas of the lung with
good oxygenation.

Answer 13

Increase blood flow to areas of the lung with

good oxygenation.

Question 14

What happens to PVR during exercise

Answer 14

PVR drops as more pulmonary capillaries open up to accommodate the increased cardiac output.

Question 15

What else does pulmonary vascular resistance depend on?

Answer 15

Also depends on lung volume
• At low or very high lung volumes, the resistance
increases a little because the stretch of the tissue
compresses the capillaries.

Question 16

Normal Value of PVR versus systemic resistance

Answer 16

Low-PVR

Moderate-systemic

Question 17

Major constrictor for PVR versus systemic resistance

Answer 17

Hypoxia-PVR

Sympathetics for systemic

Question 18

Value of PVR and systemic resistance during exercise

Answer 18

both decrease

Question 19

Major control of PVR versus systemic

Answer 19

PVR-local

systemic resistance-ANS

Question 20

regional blood flow to lungs-base

Answer 20

At the base of the lung, the blood pressure is high
because we are below the level of the heart.
• The alveoli are smaller (take that as a fact right now).
• The blood flow is greater than in other regions of the
lung

Question 21

regional blood flow to lungs-apex

Answer 21

At the apex of the lung, the blood pressure is reduced
because it is slightly above the level of the heart.
• However, the alveoli are somewhat expanded (take
that as a fact right now).
• The blood flow is less.

Question 22

summary of regional blood flow

Answer 22

Apex: high alveolar pressure, low blood pressure: Little blood
o Middle regions: Normal pressures on both sides: Normal blood
o Base: Relatively low alveolar pressure, relatively high blood pressure: Lots
of blood.

Question 23

Nitric oxide- where is it made and what does it do

Answer 23

Nitric Oxide –
o Made by the endothelium
o Causes smooth muscle relaxation and vasodilation
o Significant role in normal pulmonary blood flow

Question 24

Endothelin 1-where is it made and what does it do

Answer 24

Endothelin 1
o Also made in lungs
o Vasoconstrictor
o Seems to be a player under pathologic conditions – not under normal conditions

Question 25

thromboxane a2

Answer 25

Treat it the same as endothelin 1