Pulmonary Blood Flow

Question 1

Does the left ventricle pump more blood than the right ventricle? Does it do more work than the right?

Answer 1

No, but it does more work. Therefore its walls are thicker.

Question 2

What is the blood pressure of the atrium?

Answer 2

15/4

Question 3

What is the blood pressure of the right ventricle?

Answer 3

25/0

Question 4

What is the blood pressure of the left ventricle?

Answer 4

120/0

Question 5

If the right ventricle fails, where will fluid accumulate?

Answer 5

The lungs

Question 6

Where do alveolar capillaries get blood from?

Answer 6

The right ventricle

Question 7

Where do extra-alveolar capillaries get their blood from?

Answer 7

The left ventricle

Question 8

What is interesting about the blood flow of axtra-alveolar capillaries?

Answer 8

After o2 is delivered, the blood is returned to the left atrium in the pulmonary veins in a venous admixture. This elevates the amount of CO2 and decreases the amount of O2 in the blood. This is detectable on pulse-ox.

Question 9

PBP = what?

Answer 9

CO x PVR

(cardiac output x pulmonary vascular resistance)

Question 10

What is pumonary vascular resistance determined by? (4 things)

Answer 10

1. ) High number of capillaries
2. ) How many capillaries are open at any given moment in time
3. ) Much less sympathetic innervation. Therefore less vasodilation of the capillaries because the sympathetic response is vasodilation
4. ) Lung volumes. At low or very high lung volumes the resistance increases a bit because the stretch of the tissues compresses the capillaries

Question 11

During exercise, what happens to PVR?

Answer 11

PVR drops as more pulmonary apillaries open up to accommodate the increased CO.

Question 12

At the apex of the lung, is the blood pressure reduced or elevated? Why?

Are alveoli large or small?

Answer 12

It is reduced because it is slightly above the level of the heart. Therefore, blood flow is less.

P_A > P_a > P_v

The alveoli are large.

Question 13

In the middle of the lung, what is the blood pressure? Why?

Are the alveoli large, medium, or small?

Answer 13

The blood pressure is a little higher than the apex bc they are at the level of the heart.

The alveoli are medium sized.

Question 14

At the base of the lung, what is the blood pressure? Why?

Are the alveoli large, medium, or small?

Answer 14

The blood pressure is higher, due to gravity and the base being below the heart.

The alveoli are small.

Question 15

Where is nitric oxide made? What does it do? What is its significant role?

Answer 15

It is made in the vascular endothelium.

It causes smooth muscle relaxation and vasodilation.

It has a significant role in pulmonary blood flow.

Question 16

What are the 4 main modifiers of pulmonary blood flow?

Answer 16

1. ) Nitric oxide
2. ) Endothelin 1
3. ) Thromboxane A2
4. ) O2

Question 17

Where is endothelin 1 made? What is its function? What does it seem to do?

Answer 17

Made in the lungs

Function is vasoconstriction

Seems to be a player under pathogenic conditions

Question 18

Where is Thromboxane A2 made? What is its function? Under what conditions is it found?

Answer 18

Made in the lungs.

It functions as a vasoconstrictor.

It is found under pathogenic conditions.

Question 19

So due to starling forces, fluid generally wants to leave the capillary and enter the alveoli. What keeps them “dry”?

Answer 19

The lymphatic system

Question 20

Where is angiotensinogen produced?

Answer 20

The liver

Question 21

What converts angiotensinogen to angiotensin I?

Answer 21

Renin

Question 22

What converts angiotensin I to angiotensin II?

Answer 22

ACE

Question 23

What is the function of angiotensin I and angiotensin II?

Answer 23

Angiotensin I - weak vasoconstrictor

Angiotensin II - potent vasoconstrictor

Question 24

What does ACE inhibit? What is a possible side effect of ACE inhibitors?

Answer 24

Bradykinin. They can cause a cough due to accumulation of bradykinin.