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_Physiology Exam 4 > 3/19: Pulmonary Circulation > Flashcards

3/19: Pulmonary Circulation Flashcards

1
Q

How does pulmonary circulation compare to systemic?

A

Lower pressure
Lower resistance
Higher compliance
Lower volume

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2
Q

How do pulmonary arteries compare to systemic?

A

Larger
Walls are thin and distensible - large compliance

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3
Q

How do pulmonary capillaries compare to systemic?

A

More distensible
There is no population that is closed at rest

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4
Q

How do pulmonary veins compare to systemic veins?

A

Much shorter than systemic

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5
Q

What does bronchial circulation supply?

A

Oxygen and nutrients to the tracheobronchial tree down to the terminal bronchioles and also pulmonary blood vessels, visceral pleura, nerves, and hilar lymph nodes

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6
Q

Describe the blood in the left atrium

A

has little less oxygen (95) than in pulmonary capillaries (100) since some deoxygenated blood from
bronchial veins mixes with oxygenated blood in pulmonary

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7
Q

Bronchial flow is about ______% of cardiac output of the left ventricle

A

2%

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8
Q

How structures in the respiratory zone receive oxygen?

A

Directly by diffusion from the
alveolar air (doesn’t need bronchial circulation) and receive nutrients from the mixed venous blood in pulmonary circulation

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9
Q

What is the pressure and resistance of pulmonary circulation?

A

Low pressure
Low resistance

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10
Q

Describe pulmonary vessels

A

are far more distensible/compliant and able to alter their size and adjust to changing pulmonary volumes

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11
Q

What is the pressure of the pulmonary artery?

A

High pressure, pulsatile nature

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12
Q

What is the pressure of the pulmonary capillary?

A

pressure is not pulsatile anymore.
This pressure is right around 7 (creates pressure for
FILTRATION though the pulmonary capillaries) this
pushes fluid out of the capillaries

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13
Q

What is the pressure of the left atrium?

A

Low pressure (around 2)

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14
Q

What does pulmonary blood volume account for?

A

9% of blood volume (450 mL) but is highly variable

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15
Q

When does pulmonary blood volume increase?

A

during inspiration, laying down, and disease states

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16
Q

What is the flow in pulmonary circulation not as prone to compared to systemic?

A

Hypertension

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17
Q

How does an increase in flow (CO) to the lungs decrease pulmonary resistance through?

A
  1. Recruitment of pulmonary capillaries
    a. Opening and perfusing more
  2. Distension of pulmonary capillaries
    a. **This is why pulmonary
    circulation has compliance
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18
Q

How does the equation MAP = CO x PVR (pulmonary vascular resistance) relate to pulmonary circulation?

A

An increase in blood flow leads to a decrease in pulmonary vascular
resistance and an increase in CO
* By changing these two in the opposite direction, it doesn’t have a huge effect on MAP. Helps us keep MAP about the same

19
Q

What does matching blood flow (perfusion, Q) and ventilation (air flow, V) function to deliver?

A

Blood flow to alveoli where it will be most effective at gas exchange
Matching perfusion to ventilation

20
Q

What happens when PAO2 drops 70% below normal?

A

Adjacent blood vessels constrict

21
Q

What happens when PAO2 is high?

A

Adjacent blood vessels dilate

22
Q

What would happen throughout the pulmonary circulation at a high altitude where PAO2 is reduced?

A

Pulmonary hypertension

23
Q

What is happening during perfusion of a well ventilated alveoli?

A

Maximal gas exchange
* Blood is coming in with lower
oxygen
* Goal is to reach equilibrium
* Here we are getting maximum
gas exchange

24
Q

What is happening during perfusion of hypoventilated alveolus?

A

Results in blood with decreased PaO2 (if no vasoconstriction occurred)
Blood O2 levels would be reduced from normal if NO reflex adjustment occurs
* Hypoventilated alveolus
(airway obstruction) decrease
in air flow which leads to
decreased in paO2
* If we do nothing, then blood
o2 leaving is less than 95/100
(Not the way we want this to
work so there is a reflex)

25
Q

What does HPV allow blood to be sent to?

A

Better ventilated alveoli to maximize gas exchange

26
Q

Describe the reflex response when blood is sent to better ventilated alveoli to maximize gas exchange

A

Reflex response
* Response of the above reflex
* Vasoconstriction lets extra
blood go to a better ventilated
alveolus (arrow)

27
Q

What does HPV reduce blood flow to?

A

Hypoventilated alveoli

28
Q

Describe what happens when there is reduce blood flow to hypoventilated alveoli

A

In response to decrease PAO2, the HPV occurs
* Constriction of blood vessels
takes place (star) so we don’t
send as much blood there to
prevent that blood from not
being able to pick up enough
oxygen (again)

29
Q

What are vasodilators for pulmonary arterioles?

A

high O2 in alveoli (opposite of systemic)
Also: dopamine, bradykinin, prostacyclin, Nitric oxide, histamine, acetylcholine

30
Q

What are vasoconstrictors for pulmonary arterioles?

A

low O2 in alveoli, high CO2 in alveoli (opposite of systemic)
o Also: NE, ang II, endothelin, vasopressin, thromboxane A2

31
Q

What do lung volumes have a passive effect on?

A

Pulmonary vascular resistance (PVR)

32
Q

What are alveolar vessels?

A

near and around the alveoli, smallest (consists of pulmonary
capillaries, smallest arterioles, and venules)

33
Q

What are extra-alveolar vessels?

A

not directly next to alveoli, larger (consists of all other vessels)

34
Q

What does pulmonary vascular resistance (PVR) equal?

A

Pulmonary vascular resistance (PVR) = total of alveolar vessel and extra alveolar vessel
resistance

35
Q

What happens when the alveoli expand during INSPIRATION?

A
  1. Alveolar vessels are compressed/elongated and their resistance INCREASES
  2. Extra-alveolar vessels expands, causing decreased resistance
    - to breathe we have to decrease Pip from -5 to -7.5
36
Q

What happens when the alveoli constrict during EXPIRATION?

A
  1. Alveolar vessels: expand, decreased resistance
  2. Extra-alveolar vessels: compress, increased resistance
37
Q

When is resistance in the pulmonary circulation the lowest?

A

When lung volume is equal to FRC

38
Q

What happens to vessels during low lung volumes?

A

extra-alveolar vessel resistance increased (which increased PVR)

39
Q

What happens to vessels during high lung volumes?

A

alveolar vessel resistance increases (which increases PVR)

40
Q

When do alveolar have highest resistance?

A

high lung volumes
- due to bigger alveoli that compress the vessels in the middle of them

41
Q

When do extra-alveolar have highest resistance?

A

Low lung volumes (residual volume)
- Due to smaller alveoli

42
Q

What is FRC (functional residual capacity)?

A

“X”, the volume of the air in the lungs after a normal (TV) expiration
▪ Lowest pulmonary vascular resistance

43
Q

When is resistance in the pulmonary circulation the LOWEST?

A

when lung volume is equal to FRC

_Physiology Exam 4 (8 decks)

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