Final: Lecture 23

Question 0

Left side heart failure can cause pressure to build up in pulmonary circulation.

Answer 0

• Increases blood volume as much as 100%
• Increases BP
• Mild systemic effect b/c systemic blood volume is 9 times that of pulmonary system

Question 1

How much blood is within the pulmonary circulation?

Answer 1

• 450 ml, 9% total blood volume

* 70 ml is in pulmonary capillaries

Question 2

Blood getting through the lungs without being oxygenated is called?

Answer 2

• Physiologic shunt, about 2% in systemic arteries is blood that has bypassed the pulmonary capillaries
• Coming from lung parenchyma and left side of heart

Question 3

No blood flow, local alveolar capillary never rises higher than alveolar air pressure is what zone in the lungs?

Answer 3

•Zone 1

Question 4

Intermittent blood flow (only during systole) is ________.

Answer 4

•Zone 2

Question 5

Zone 3 has ________ blood flow.

Answer 5

•Continuous

Question 6

Normally, apices have _______ flow, and lower areas have _______ flow.

Answer 6

• Zone 2
• Zone 3
• Exercise can convert apices from zone 2 to zone 3 flow

Question 7

If one lung doesn’t function what happens?

Answer 7

• the other lung blood flow doubles

* b/c of passive dilation of pulmonary vessels, the pulmonary pressure in the other lung is only slightly increased

Question 8

Agents that constrict pulmonary arterioles.

Answer 8

• Norepinephrine
• Epinephrine
• Angiotensin II
• Some prostaglandins

Question 9

Agents that dilate pulmonary arterioles.

Answer 9

• Isoproterenol

* Acetylcholine

Question 10

Agents that constrict pulmonary venuels.

Answer 10

• Serotonin
• Histamine
• E. coli endotoxin

Question 11

Sympathetic vasoconstrictor nerve fibers:

Answer 11

• Outflow from cervical sympathetic ganglia
• Decrease pulmonary blood flow by as much as 30%
• Mobilize blood from pulmonary reserve

Question 12

During heavy exercise, blood flow through lungs increases ____ to ___.

Answer 12

• 4x to 7x
• Increases number of open capillaries up to 3x
• Distends all capillaries and increased flow rate up to 2x
• Increases pulmonary arterial pressure
• Pulmonary arterial pressures rises little even during maximum exercise, conserve energy to right side of heart, prevents significant rise in pulmonary capillary pressure

Question 13

Left-Sided heart failure

Answer 13

• Pressure never normally rises above +6 mm Hg.
• blood begins to dam up in LA
• left arterial pressure rises from 1-5 mm Hg to 40-50 mm Hg
• Increased above 8 mm Hg cause equal increases in pulmonary arterial pressure, above 30 mm Hg, pulmonary edema is likely

Question 14

Lung capillary fluid exchange

Answer 14

• Hydrostatic pressure = +7
• Interstitial fluid osmotic pressue = (-)14
• Interstitial fluid hydrostatic pressure = (-)8
• Total outward force = 29

Question 15

Capillary osmotic pressure is?

Answer 15

• 28 mm Hg, so total inward force equals 28

* Mean filtration pressure = +29 - 28 = 1mm Hg

Question 16

Excess fluid can be carried away by what?

Answer 16

•pulmonary lymphatics, keep alveoli dry

Question 17

Pulmonary Edema

Answer 17

• Occurs when pulmonary capillary pressure > 25 mm Hg
• Most common cause: left-sided heart failure or mitral valve disease, damage to pulmonary blood capillary membranes
• Lethal pulmonary edema can occur within hours to minutes

Question 18

What might happen when capillary pressure remains chronically elevated for two weeks or more?

Answer 18

•person can compensate over a period of time

Question 19

Pleural Effusion

Answer 19

• Pumping of fluid from pleural space by lymphatics creates a normal pressure in pleural space of -7 mm Hg.
• If this pressure becomes more positive (-4 mm Hg) the lungs tend to collapse
• Pleural effusion is edema of the pleural cavity

Question 20

Causes of Pleural effusion

Answer 20

• Blockage of lymphatic drainage from pleural cavity
• cardiac failure
• Considerably reduced plasma colloid osmotic pressure
• Infection/inflammation

Question 21

Hypoxia (reduced oxygen) increased pressure in the pulmonary artery, possibly b/c of the release of ________.

Answer 21

•Prostaglandin

Question 22

Hypoxia results in bronchial obstruction because?

Answer 22

• constriction of vessels supplying the poorly ventilated alveoli
• due to locally low alveolar pO2, drop in pH due to accumulation of CO2
• Decline in pH produces vasoconstriction in pulmonary vessels
• Decline in pH produces vasodilation in other tissues*