HRR: pulmonary circulation

Question 1

What is the approximate volume of the lungs?

Answer 1

500 mL

Question 2

What is the capillary volume in the lungs?

Answer 2

75 mL

Question 3

What are the circulations in the lungs?

Answer 3

Pulmonary and bronchial

Question 4

Describe pulmonary circulation.

Answer 4

It involves the reoxygenation of blood delivered from the right heart. It is 100% of cardiac output.

Question 5

Which circulation in the lungs is involved in generation of pleural fluid?

Answer 5

Pulmonary

Question 6

Describe bronchial circulation.

Answer 6

Involved in the oxygenation of bronchioles and is about 2% of cardiac output.

Question 7

Pulmonary circulation is a ___ pressure, ___ resistance, and ___ compliance circulation.

Answer 7

Low, low, high

Question 8

How are extra alveolar vessels impacted by alveolar pressure?

Answer 8

They’re not!

Question 9

How are extra alveolar vessels impacted by intrapleural/interstitial pressure?

Answer 9

Their caliber is impacted by lung volumes; a higher volume decreases intrapleural pressure, which will increase diameter of the vessels.

Question 10

How are alveolar vessels impacted by alveolar pressure?

Answer 10

A high alveolar volume increases alveolar pressure and causes a decreased diameter of the vessels.

Question 11

As pulmonary artery pressure goes up, what happens to resistance?

Answer 11

It goes down! This is due to distension and recruitment of pulmonary capillary beds.

Question 12

What is passive regulation?

Answer 12

The capacity of pulmonary capillaries to adjust to changes in flow and pressure while keeping resistance low.

Question 13

What is active regulation?

Answer 13

Local hypoxia causes vasoconstriction, allowing for more blood to be sent to areas of oxygenation. The same process with generalized hypoxia causes increased PVR, PH, and right heart hypertrophy. This occurs at small arteries and arterioles.

Question 14

What is the primary factor of active regulation?

Answer 14

Alveolar oxygen tension

Question 15

What is a main vasodilatory in pulmonary vasculature?

Answer 15

Low PACO2

Question 16

What is a main vasoconstrictor in pulmonary vasculature?

Answer 16

High PACO2

Question 17

Which zone of the lung gets the most blood?

Answer 17

Zone 3 (lower lung)

Question 18

Which zone of the lung gets the most ventilation?

Answer 18

Zone 3 (lower lung)

Question 19

Describe an anatomic shunt in the pulmonary vasculature.

Answer 19

Venous blood bypasses oxygenation at the capillary and gets directly into arterial circulation.

Question 20

Why does pulmonary edema occur in HF?

Answer 20

Normally, filtration is favored in the lung vasculature. In normal conditions the lymphatic system can handle this to prevent excess fluid in the lungs. However, increased LV pressure causes a back pressure into the atrium, then the pulmonary veins, then the capillaries. This causes even more filtration to account for the pressure increase, and the lymphatics can’t handle the volume.