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Human Physiology > Human Phys 6.7 > Flashcards

Human Phys 6.7 Flashcards

1
Q

What is the blood volume in the lungs?

A

450 mL (9% of total blood volume in entire circulatory system)

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2
Q

How much of the blood volume of the lungs is in the pulmonary capillaries?

A

70mL (15%)

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3
Q

What happens to the remained of blood volume that is not in the pulmonary capillaries?

A

It is divided equally between the pulmonary arteries and the veins

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4
Q

What is the volume of systemic circulation?

A

9x greater than the pulmonary system

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5
Q

How does a shift from one system to another affect the pulmonary system?

A

Greatly

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6
Q

How does a shift of blood from one system to another affect the systemic circulation?

A

Only mildly (because of much higher volume)

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7
Q

How much blood can be expelled from the pulmonary circulatory system to the systemic circulation during periods of high thoracic and pulmonary pressures?

A

250 mL or blood (when someone blows a trumpet)

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8
Q

How can loss of blood from the systemic circulation by hemorrhage be compensated?

A

By the automatic shift of blood from the lungs into the systemic vessels

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9
Q

Systolic pulmonary artery pressure

A

25mmHg

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10
Q

Diastolic pulmonary artery pressure

A

8 mmHg

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11
Q

Mean pulmonary artery pressure

A

15 mmHg

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12
Q

Capillary pulmonary artery pressure

A

7 mmHg

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13
Q

What is blood flow through the lungs equal to?

A

CO

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14
Q

What do the pulmonary vessels act as under most conditions?

A

Passive, distensible tubes that enlarge with increasing pressure and narrow with decreasing pressure

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15
Q

What is important for adequate respiration to occur?

A

Blood to be distributed to those segments of the lungs where the alveoli are best oxygenated

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16
Q

What is the total surface area of the respiratory membrane in healthy adult males?

A

70 m^2

17
Q

What occurs in systemic vessels when O2 is decreased?

A

Vasodilation

18
Q

What occurs in pulmonary vessels when O2 is decreased?

A

Vasoconstriction

19
Q

When is pulmonary blood flow autoregulation more pronounced?

A

When O2 concentration falls below 70% of normal

20
Q

What is the pulmonary blood flow autoregulation important for?

A

Proper distribution of blood flow and avoidance of alveoli that are not adequately oxygenated

21
Q

When does the pulmonary blood flow autoregulation fail?

A

When there is a widespread lung disease

22
Q

What is the lowest point of the lungs in a normal upright adult?

A

30 cm below the highest point

23
Q

What is the normal pressure difference in the lungs?

A

23 mmHg (15 above the heart and 8 below)

24
Q

What is the pulmonary arterial pressure in the uppermost portion of the lungs in standing?

A

15 mmHg less than the pulmonary arterial pressure at the level of the heart

25
Q

What is the pressure in the lowest portion of the lungs?

A

8 mmHg greater than the level of the heart

26
Q

What is the flow of the blood in the lungs when standing at rest?

A

Little flow at top of lungs but 5x as much in the bottom

27
Q

Zone 2 blood flow of lungs

A

Intermittent flow in the apices

28
Q

Zone 3 blood flow of lungs

A

Continuous flow in all the lower areas

29
Q

What is the lung like in supine?

A

No part of the lung is more than a few cm above the level of the heart

30
Q

What is the blood flow in a normal person?

A

Entirely zone 3

31
Q

How does blood flow increase during heavy exercise?

A

4-7 fold

32
Q

How is the extra flow in the lungs accommodated for?

A

Increasing the number of open capillaries (sometimes as much as threefold)

Dilating all the capillaries and increasing the rate of flow through each capillary more than twofold

Increasing the pulmonary arterial pressure

33
Q

What do the first two changes in the accommodation of blood flow cause?

A

Decrease in pulmonary vascular resistance so much that the pulmonary try arterial pressure rises very little (even during maximum exercise)

34
Q

What does the ability of the lungs to accommodate greatly increased blood flow during exercise without increasing the pulmonary arterial pressure do?

A

Conserves energy of the right side of the heart and preventing the development of pulmonary edema

35
Q

What is a shunt?

A

When a portion of blood flow is diverted from one place to another

36
Q

Physiological shunt

A

About 2% of CO bypasses alveoli

Bronchial blood flow

Small amount of coronary blood flow drains directly into the LV

Explains why PaO2 will always be slightly lower than PAO2

37
Q

Right to left shunt

A

Shunting the blood from the right heart to the left heart due to a defect in the ventricular wall

50% of CO can bypass lungs

Hypoxemia always occurs

Cannot be corrected by breathing 100% O2

38
Q

Left to right shunt

A

More common

Do not cause hypoxemia

Oxygenated blood from the left heart is added back to the right heart

Right heart CO becomes larger than left heart CO

Human Physiology (41 decks)

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