Pulmonary Blood Flow

Question 1

What supplies blood to the lung? What percentages of L and R ventricular output does the lung receive?

Answer 1

Bronchial circulation through bronchial arteries and through pulmonary circulation; 2% of L and 100% of R

Question 2

To what point in the tracheobrochial tree do bronchial arteries run?

Answer 2

Down to terminal bronchioles

Question 3

How do respiratory bronchioles receive oxygen and nutrients?

Answer 3

They get oxygen directly from the air and nutrients from pulmonary circulation

Question 4

How does bronchial drainage occur?

Answer 4

Part drains into the azygous v. and part drains directly into the pulmonary vein (normal anatomic shunt)

Question 5

If the left side of the heart begins to out perform the right side, what will occur? The right outperforming the left?

Answer 5

Peripheral edema; Pulmonary edema

Question 6

What is the resistance of pulmonary blood flow relative to systemic resistance to blood flow? Why?

Answer 6

Pulmonary blood flow has lower resistance because vessels in pulmonary circulation are more extensible

Question 7

Where does the most resistance to blood flow occur in pulmonary circulation?

Answer 7

Capillaries

Question 8

In which capillaries is flow pulsitile? Non-pulsitile?

Answer 8

Pulsitile in pulmonary circulation and non-pulsitile in systemic circulation

Question 9

What is the equation for determining pulmonary vascular resistance?

Answer 9

resistance= (Mean pulmonary artery pressure- mean left atrial pressure)/ pulmonary blood flow

Question 10

True or False: Most of the time pressure and flow determine the resistance of pulmonary circulation

Answer 10

True

Question 11

What is the approximate ratio of capillaries to alveoli?

Answer 11

900: 1

Question 12

What layers must a molecule of oxygen pass through before it can combine with hemoglobin?

Answer 12

Alveolus, thin layer of surfactant, alveolar endothelium, interstitial space, capillary endothelium, plasma, RBC membrane

Question 13

What two types of vessels need to be considered in pulmonary vascular resistance?

Answer 13

Extra-alveolar and alveolar vessels

Question 14

When inspiring deeply, what happens to the resistance in the extra-alveolar vessels? the alveolar vessels?

Answer 14

Extra-alveolar vessel resistance decreases and alveolar resistance increases

Question 15

What makes the extra-alveolar vessels open during a deep breath?

Answer 15

Traction from filled alveoli, and intrapleural pressure is getting more negative and so transmural pressure gradient is increasing

Question 16

Which pulmonary vessels increase in resistance during inspiration from FRC to the TLC? From the FRC to the RV?

Answer 16

Alveolar vessels; Extra-alveolar vessels

Question 17

What is the relationship between blood flow and pulmonary vascular resistance?

Answer 17

Increased blood flow decreases pulmonary vascular resistance

Question 18

What are the two mechanisms by which increased mean pulmonary artery pressure may decrease pulmonary vascular resistance?

Answer 18

Distension and recruitment

Question 19

What is the effect of increased and decreased lung volume on pulmonary vascular resistance?

Answer 19

Increased

Question 20

What is the effect of increased blood pressure or increased cardiac output on pulmonary vascular resistance?

Answer 20

Decreased

Question 21

What is the effect of sympathetic stimulation on pulmonary vascular resistance?

Answer 21

Increased resistance

Question 22

What molecules increase pulmonary vascular resistance?

Answer 22

Norepinephrine, epinephrine, alpha-adrenergic agonists, thromboxane, PGF2alpha, PGE2, angiotensin, endothelin, and histamine

Question 23

What compounds decrease pulmonary vascular resistance?

Answer 23

ACh, beta-adrenergic agonists, PGE1, prostacylin, NO, and brandykinin

Question 24

What region of the lung has the most blood flow when upright? Why?

Answer 24

There is more blood flow in lower parts of the lung because there is greater pressure at the bottom and therefore more recruitment and distension

Question 25

What serves as the downstream pressure in pulmonary blood flow in zone 2 of the lung?

Answer 25

Alveolar pressure

Question 26

In what zone of the lung is both pulmonary artery and pulmonary vein pressures greater than alveolar pressure?

Answer 26

Zone 3

Question 27

Roughly what percent of the lung should be zone 1 in a young, healthy adult?

Answer 27

Should be no zone 1 because that is alveolar dead space

Question 28

What is HPV in the context of pulmonary physiology? What is it?

Answer 28

Hypoxic Pulmonary Vasoconstriction- Pulmonary blood pressure increased and vessels constricted in response to hypoxia

Question 29

What is the effect of hypoventilation on arterial O2 and CO2?

Answer 29

Hypoventilation decreases O2 and increases CO2

Question 30

How does HPV help to maintain V/Q?

Answer 30

HPV increases the resistance to blood flow to hypoventilated alveoli- this diverts blood flow away from the hypoventilated alveolus to better ventilated alveoli