Lecture 3: Pulmonary Blood Flow

Question 1

Where does blood entering alveolar capillary come from?

Answer 1

Right ventricle via pulmonary artery

Question 2

What is the function of an alveolar capillary?

Answer 2

Gas exchange

• remove carbon dioxide
• receive oxygen

Question 3

Where does blood entering extra-alveolar capillary come from?

Answer 3

Left ventricle via aorta

Question 4

What is the function of an extra-alveolar capillary?

Answer 4

Provide nutrients to and remove waste from airways

Question 5

How does blood from an extra-alveolar capillary return to the heart?

Answer 5

Pulmonary vein

-will slightly decrease oxygen content of arterial blood and increase carbon dioxide (venous admixture)

Question 6

How do you calculate pulmonary blood pressure?

Answer 6

Pulmonary BP = Cardiac Output x Pulmonary Vascular Resistance

Question 7

Why is pulmonary vascular resistance so low?

Answer 7

• High number capillaries

- Less sympathetic tone

Question 8

During exercise, does PVR increase or decrease? Why?

Answer 8

Decreases since more pulmonary capillaries open up to accomodate for increased cardiac output

Question 9

In the apex of the lung, there is:
\_\_\_\_ alveolar pressure
\_\_\_\_ blood pressure
\_\_\_\_ blood flow
\_\_\_\_ size of alveoli

Answer 9

In the apex, there is:
HIGH alveolar pressure
LOW blood pressure
LOW blood flow
LARGE size of alveoli

Question 10

In the middle region of the lung, there is:
\_\_\_\_ alveolar pressure
\_\_\_\_ blood pressure
\_\_\_\_ blood flow
\_\_\_\_ size of alveoli

Answer 10

In the middle region of the lung, there is:
NORMAL alveolar pressure
NORMAL blood pressure
NORMAL blood flow
AVERAGE size of alveoli

Question 11

In the base region of the lung, there is:
\_\_\_\_ alveolar pressure
\_\_\_\_ blood pressure
\_\_\_\_ blood flow
\_\_\_\_ size of alveoli

Answer 11

In the base region of the lung, there is:
LOW alveolar pressure
HIGH blood pressure
HIGH blood flow
SMALL size of alveoli

Question 12

What is the role of nitric oxide?

Answer 12

Smooth muscle relaxation and vasodilation

• important role in normal pulmonary blood flow
• made by endothelium

Question 13

What is the role of endothelin 1 and thromboxane A2?

Answer 13

Vasoconstrictor

-found in pulmonary vasculature

Question 14

In the lungs, what forces are pushing fluid out of the capillaries into the alveoli?

Answer 14

1. Pc (hydrostatic pressure of capillaries): push fluid out of capillaries
2. Pt (hydrostatic pressure of tissue - unique in lungs): Negative pressure in lung tissue favors fluid pushed out of capillaries
   πt (oncotic pressure of tissue): pulls water into alveoli

Question 15

In the lungs, what forces are pushing fluid into the capillaries?

Answer 15

πc

Question 16

Water in the alveoli is not good for oxygen diffusion. How does the body compensate for this?

Answer 16

Lymphatics drain water in alveoli

Question 17

What enzyme converts angiotensinogen to angiotensin 1?

Answer 17

Renin

Question 18

Where is renin made?

Answer 18

Liver but released by kidneys

Question 19

What converts angiotensin 1 to angiotensin 2?

Where is this enzyme found?

Answer 19

ACE

Question 20

Where is ACE found?

Answer 20

Lungs

Question 21

What does ACE inactivate?

Answer 21

Bradykinin

Question 22

What does angiotensin do?

Answer 22

Vasoconstrictor (increases BP)

Question 23

Why do some people with high BP and are placed on ACE inhibitors develop a cough?

Answer 23

Accumulation of bradykinin

Question 24

Lungs participate in the metabolism of what?

Answer 24

Arachidonic Acid Metabolites

• leukotrienes
• prostaglandins E2 and F2α
• thromboxane A2