Lecture 23 - Pulmonary Circulation

Question 1

The pulmonary artery is thinner (almost 1/3) than the aorta. Why is this advantageous?

Answer 1

The thin wall of the pulmonary artery allows for greater arterial compliance. Therefore, the pulmonary arteries act to accommodate the output of the right ventricle.

Question 2

The lung has two circulatory routes, one of high pressure/low flow, and one of low pressure/high flow.

Which one is responsible for supplying the alveoli?

Answer 2

Low pressure, high flow

Question 3

The pulmonary artery systolic pressure is closest to which of the following?

A. 9 mmHg
B. 15 mmHg
C. 25 mmHg
D. 40 mmHg

Answer 3

C. 25 mmHg

Question 4

The pulmonary artery diastolic pressure is closest to which of the following?

A. 9 mmHg
B. 15 mmHg
C. 25 mmHg
D. 40 mmHg

Answer 4

A. 9 mmHg

Question 5

The mean pulmonary artery pressure is closest to which of the following?

A. 9 mmHg
B. 15 mmHg
C. 25 mmHg
D. 40 mmHg

Answer 5

B. 15 mmHg

Question 6

The left atrial pressure is closest to which of the following?

A. 9 mmHg
B. 15 mmHg
C. 25 mmHg
D. 40 mmHg

Answer 6

A. 9 mmHg

Question 7

Describe how one obtains the pulmonary wedge pressure

Answer 7

Steps:

1) insert catheter f/ peripheral v. to the right atrium
2) continue insertion through the right heart through the pulm. a. into a small branch of the pulmonary a.
3) continue insertion until the catheter wedges into a small branch of the pulmonary artery

“The blood flow has been stopped in the small wedged artery.”

Question 8

Failure of the right heart can lead to build up of stagnant blood in the pulmonary circulation, T/F

Answer 8

False. Left sided heart failure produces pulmonary problems

Question 9

When blood in the left atrium is measured, it contains less oxygen than is expected. This is due to:

a. COPD, a disease that prevents the diffusion of O2/CO2 at the alveoli
b. Mixing of deoxygenated blood that has been dumped into the pulmonary vein after delivering O2 to the lung parenchyma
c. Bypassing of blood around the pulmonary artery and through the descending abdominal aorta

Answer 9

b. Mixing of deoxygenated blood that has been dumped into the pulmonary vein after delivering O2 to the lung parenchyma

Physiologic shunt supplies oxygen to the lung parenchyma itself

Question 10

Decreased alveolar PO2 regulates pulmonary blood flow. It is believed to be due to oxygen sensitive potassium channels closing, which produces (by calcium influx) vasoconstriction in the poorly perfused alveolar capillaries.

Below what PO2 does this occur?

A. 90%
B. 80%
C. 70%
D. 60%

Answer 10

C. 70%

Question 11

Unless experiencing a pathological condition, this zone receives no blood flow, as capillary pressure is less that alveolar pressure.

A. Zone 3
B. Zone 2
C. Zone 1

Answer 11

C. Zone 1

Question 12

This region of lung tissue receives blood only during systole (P capillary > P alveoli).

Answer 12

Zone 2

Question 13

The lung apices normally have zone ____ blood flow.

A. 3
B. 2
C. 1

Answer 13

B. 2

Question 14

Continuous blood flow is found in zone ____.

Answer 14

3

Question 15

Lower lung regions have zone ____ flow.

A. 3
B. 2
C. 1

Answer 15

A. 3

Question 16

The pulmonary veins can release up to ____ mL of blood upon an individual standing.

Answer 16

400

Question 17

Dilation of ____ in a lung occurs when blood flow to the other lung is ceased.

Answer 17

pulmonary vessels

Question 18

Dilation of pulmonary arterioles occurs with every drug but:

A. isoproteronol
B. Angiotensin II
C. Acetylcholine

Answer 18

B. Angiotensin II

Question 19

Constriction of pulmonary arterioles occurs with every drug except:

A. Norepinephrine
B. Acetycholine
C. Prostaglandins
D. Epinephrine

Answer 19

B. acetylcholine

Question 20

Serotonin, histamine, and e. coli endotoxin all act to constrict pulmonary (arterioles/venules)

Answer 20

venules

Question 21

Pulmonary arterial pressure rises very little during exercise. Why is this so?

A. Increased blood flow opens capillaries
B. Increased blood flow distends capillaries
C. Both A and B are correct
D. Blood flow is shunted to major muscle groups being used in exercise

Answer 21

C. A & B are correct

Though pulmonary arterial pressure is increased some, the distention and opening of capillaries in the lungs causes a larger volume of vessel for the blood to occupy.

Think of distensibility: P/V; in exercise, the volume is increased, though the opened vessels allow for more area for that volume to occupy, thereby keeping pressure changes minimal.

Question 22

In left heart failure, the pressure in the left atrium can rise from 1-5 mmHg to up to _____ mmHg.

Answer 22

50 mmHg

Question 23

Increases of left atrial pressure greater than ____ produces equal changes to pulmonary arterial pressure.

A. 2 mmHg
B. 5 mmHg
C. 8 mmHg
D. 10 mmHg

Answer 23

C. 8 mmHg

Question 24

What are the three most common causes of pulmonary edema?

Answer 24

1) Left sided heart/mitral valve disease
2) Damage to pulmonary capillary membranes by infection
3) Damage to pulmonary capillary membranes by noxious substances (ex: phosgene gas)

Question 25

Edema of the pleural cavity is known as ____.

Answer 25

pleural effusion

Question 26

Pumping of fluid from the pleural space usually results in a pleural pressure of _____.

Answer 26

-7 mmHg

Question 27

Lowered PO2 in poorly ventilated alveoli produces (vasodilation/vasoconstriction)

Answer 27

Vasoconstriction (Prostaglandin mediated)

pH drops due to increased PCO2, which produces vasoconstriction. This is OPPOSITE of the changes induced by increased PCO2 in other tissues

Question 28

The lung has two circulatory routes, one of high pressure/low flow, and one of low pressure/high flow.

Which one is responsible for supplying the CT/trachea/bronchial tree/lung parenchyma

Answer 28

High pressure, low flow.