Blood Flow and Metabolism

Question 1

pulmonary artery structure?

Answer 1

little smooth muscle

ensures high compliance

Question 2

pulmonary pressure?

Answer 2

lower mean 15mmHg

Question 3

systemic pressure?

Answer 3

high mean 100mmHg

Question 4

transmural pressure

Answer 4

pressure difference between inside and outside of capillaries

Question 5

as lung expands

Answer 5

larger vessels expand

Question 6

alveolar vessels?

Answer 6

subject to changes in alveolar pressure and pressure within in them

Question 7

extra-alveolar vessels?

Answer 7

subject to changes in lung volume (pull of parenchyma)

also, have smooth muscle

Question 8

pulmonary vascular resistance

Answer 8

much lower than systemic

decreases with increased pressure**

Question 9

two reasons for drop in pulmonary vascular resistance with increased pressure?

Answer 9

recruitment and distension**

Question 10

distension

Answer 10

widening of indiviual capillary segments

Question 11

when do pulmonary capillaries collapse?

Answer 11

alveolar pressure exceeds capillary pressure

Question 12

vasodilators?

Answer 12

ACh
isoproterenol
NO
prostacyclins

Question 13

vasoconstrictors?

Answer 13

serotonin
histamine
NE

Question 14

vascular resistance = ?

Answer 14

input P - output P / blood flow

Question 15

PVR increase?

Answer 15

• high and low long volumes

- alveolar hypoxia (vasoconstriction)

Question 16

pulmonary vascular resistance falls?

Answer 16

with increasing arterial or venous pressure

Question 17

distribution of blood flow in lung?

Answer 17

more to base of lung

• explained by hydrostatic pressure differences
• base of lung has higher arterial pressure

Question 18

zone 1 of lung?

Answer 18

may be present

• where the pulmonary arterial pressure falls below alveolar pressure
• causes capillaries to be squished (no flow)

maybe during severe hemorrhage, or positive pressure ventilation

Question 19

ventilated bu not perfused lung?

Answer 19

alveolar dead space

Question 20

venous pressure

Answer 20

only has an impact on flow if it exceeds alveolar pressure

aka starling resistor

Question 21

change in pulmonary resistance with change in lung volume?

Answer 21

high resistance at high and low volume

high - because increased alveolar resistance
-increased alveolar pressure and stretching of capillary wall

low - extra-alveolar vessels are constricted at lower volumes (increasing resistance)

Question 22

what controls alveolar vasoconstriction?

Answer 22

alveolar PO2

ex/ traveling to high altitude (low PiO2)

Question 23

increased lung volume?

Answer 23

increased PVR

-lengthening and compression of pulmonary capillaries

Question 24

decreased lung volume?

Answer 24

decreased PVR

-compression and loss of traction of extra-alveolar vessels

Question 25

increased pulmonary artery pressure, left atrial pressure, pulmonary blood volume, cardiac output?

Answer 25

decreased PVR | -recruitment and distension

Question 26

gravity?

Answer 26

decreased PVR | -recruitment and distension (because of hydrostatic effects)

Question 27

increased interstitial pressure?

Answer 27

increased PVR | -compression of vessels

Question 28

increased blood viscosity

Answer 28

increased PVR | -increased resistance

Question 29

positive pressure ventilation?

Answer 29

increased alveolar pressure increases PVR -compression of alveolar vessels positive intrapleural pressure increases PVR -compression of extra-alveolar vessels, decreased in pulmonary blood flow

Question 30

hypoxic pulmonary vasoconstriction

Answer 30

in arterioles of hypoxic area of lung -smooth muscle contraction determined by PO2 of ALVEOLAR GAS

Question 31

fluid collection in lungs?

Answer 31

first to interstitial then to alveolar space determined by starling equation

Question 32

causes of pulmonary edema?

Answer 32

``` increased hydrostatic pressure increased capillary permeability reduced lymph drainage decreased interstitial pressure decreased colloid osmotic pressure ```

Question 33

nitric oxide?

Answer 33

endothelium-derived factor | relaxes pulmonary vessels and capillaries

Question 34

norepinephrine?

Answer 34

SNS vasoconstrictor

Question 35

endothelins?

Answer 35

constrict pulmonary vessels and capillaries

Question 36

ACE?

Answer 36

in lung, converts ANG I to ANG II

Question 37

bradykinin?

Answer 37

inactivated by ACE in lung

Question 38

serotonin?

Answer 38

inactivated by uptake and storage in lung

Question 39

prostaglandins E1, E2, F2a?

Answer 39

inactivated in lung

Question 40

NE?

Answer 40

partially taken up in the lung

Question 41

increased cardiac output?

Answer 41

pulmonary vascular resistance falls