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PHGY 210 > Respiration lecture 3 > Flashcards

Respiration lecture 3 Flashcards

1
Q

Which system is the low-pressure system?

A

Pulmonary circulation

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2
Q

Which system is the high pressure system?

A

Systemic circulation

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3
Q

During its systole, what pressure does the right ventricle develop?

A

about 25 mmHg

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4
Q

During its systole, what pressure does the left ventricle develop?

A

about 120 mmHg

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5
Q

What happens to the pressure in the right ventricle when systole ends?

A

The pressure drops rapidly

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6
Q

During diastole, what pressure does the pulmonary circulation have?

A

about 8 mmHg

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7
Q

What is the mean pulmonary arterial pressure?

A

15 mmHg

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8
Q

What is the mean systemic pressure?

A

100 mmHg

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9
Q

The drop in pressure of the pulmonary circulation is ___ than the drop in pressure of the systemic circulation

A

much smaller

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10
Q

What is the formula for flow?

A

Flow = pressure/resistance

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11
Q

Why is there low vascular resistance in the pulmonary circulation?

A

Because the walls of the blood vessels are thinner

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12
Q

What allows the lungs to accept the whole cardiac output at all times?

A

The low vascular resistance and high compliance of the pulmonary circulation

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13
Q

What kind of resistance does the pulmonary system have?

A

Low resistance

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14
Q

What is the cardiac output of each system?

A

the same

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15
Q

What kind of blood vessel walls are there in the pulmonary circulation?

A

thin and contain less smooth muscle than comparable vessels in the systemic circulation (offer less resistance)

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16
Q

What happens to pulmonary resistance as pulmonary blood flow increases?

A

Resistance has to be decreased to allow more flow foe the same pressure

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17
Q

What happens during recruitment of closed vessels?

A

Blood vessels that are closed at rest open to allow more flow at the same pressure

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18
Q

What happens during distention of blood vessels?

A

The blood vessels that are already open get bigger (dilation) to allow more flow for the same pressure

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19
Q

What are the 2 ways resistance can decrease?

A

There can be recruitment and/or distension to accommodate the larger flow without increasing the pressure

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20
Q

Which drugs cause contraction of vascular smooth muscle?

A

Serotonin
Histamine
Norepinephrine

21
Q

What do serotonin, histamine and norepinephrine do to pulmonary vascular resistance in larger pulmonary arteries?

A

it increases resistance

22
Q

Which drugs relax smooth vascular muscle?

A

acetylcholine
isoproterenol

23
Q

What does acetylcholine and isoproteranol do to pulmonary vascular resistance?

A

it decreases resistance

24
Q

What happens in regions of the lungs that are poorly oxygenated? Why?

A

There is a reflex vasoconstriction
It avoids sending blood to poorly ventilated regions and having poorly oxygenated blood

25
Q

What produces nitric oxide?

A

endothelial cells

26
Q

Which drug relaxes vascular smooth muscle?

A

nitric oxide

27
Q

What does nitric oxide lead to?

A

vasodilation

28
Q

What is pulmonary blood flow affected by?

A

gravity

29
Q

In the upright position, how does blood flow increase?

A

in a linear relation, blood flow is higher at the bottom of the lungs and lower at the top of the lungs

30
Q

Why are the vessels more distended toward the bottom of the lungs?

A

because gravity increases vascular pressure at the bottom of the lungs

31
Q

How can the pulmonary capillaries be if alveolar pressure is greater than blood pressure in the capillaries?

A

compressed

32
Q

Where is there more blood flow, at the bottom of the lungs or at the top?

A

bottom

33
Q

What causes an uneven distribution of blood flow from the top to bottom of the lung

A

the hydrostatic pressure of the blood

34
Q

What are the 3 zones of the lungs?

A

top (zone 1)
middle (zone 2)
bottom (zone 3)

35
Q

How is the pulmonary arterial pressure vs the alveolar pressure in the top zone of the lungs?

A

Pa < PA

36
Q

What happens to the capillaries in the top zone of the lungs?

A

They are compressed

37
Q

How is the pulmonary arterial pressure vs the alveolar pressure vs venous pressure in the middle zone?

A

Pv<PA<Pa

38
Q

What does the flow depend on in the middle zone of the lungs?

A

the difference between the alveolar and arterial pressures. If Alveolar pressure is greater there is no more flow

39
Q

Explain the effect of each pressure in the middle zone

A

Pv is smaller than PA so the blood vessel is compressed. Pv is not a variable to consider in this case

PA and Pa determine the flow because if Pa > PA, blood will flow but if it changes into PA>Pa, the flow will be completely cut off like in the top portion

40
Q

How is the pulmonary arterial pressure vs the alveolar pressure vs venous pressure in the bottom zone of the lungs?

A

Pa>Pv>PA

41
Q

What does the flow depend on in the bottom zone of the lungs?

A

The difference in pressure between the arterial and veinous blood, the pressure gradient

42
Q

What affects the distribution of ventilation?

A

Gravity

43
Q

In an upright lung at rest, what happens to the alveoli at the top of the lungs?

A

They are more open than the bottom ones

44
Q

During breathing, are the alveoli at the top of the lungs or at the bottom of the lungs opened wider?

A

Since the top alveoli are already open, they don’t have much more space for “new” air. The bottom alveoli will open more (in comparison to resting state)

45
Q

Why is there more fresh air at the bottom of the lungs?

A

A greater change in pressure happens

46
Q

Ventilation increases slowly from ___ to ___ of the lung but blood flow increases more rapidly.

A

top
bottom

47
Q

How is the ventilation-perfusion ratio at the top vs at the bottom?

A

it is high at the top and much lower at the bottom

48
Q

What is Fick’s principle?

A

O2 consumption per minute is equal to the O2 taken up by the blood in the lungs in one minute

PHGY 210 (8 decks)

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