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Craab 2.5 > Metabolism and blood flow > Flashcards

Metabolism and blood flow Flashcards

1
Q

What is the pressures in the pulmonary capillaries?

A

25/8mmHg normally

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2
Q

What are some dz states that can alter this pulmonary capillary pressure?

A

CHF

Emphysema

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3
Q

What are the alveolar pressures?

A

Pulmonary capillary pressure

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4
Q

What the alveolar pressures during inspiration and exhalation?

A

Sub atmospheric during inspiration

- about 2 atm’s during exhalation

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5
Q

How does the change in alveolar pressures affects pulmonary capillaries?

A

Increase pressure during exhalation causes pulmonary capillaries to close
- during inspiration these capillaries distend due to low alveolar pressures

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6
Q

What are a couple examples that close pulmonary capillaires? Where typically?

A

Positive ventilation
Tension pneumo
- both at the apex

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7
Q

What are some ways to decrease pulmonary resistance?

A
  1. Increased recruitment of caps
  2. Distention

Caused by increase pulmonary arterial pressure

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8
Q

What are some ways to increase pulmonary capillary resistance?

A
  • Increase alveolar pressure via exhalation

- NE and Serotonin

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9
Q

What affect does Ach have on pulmonary resistance?

A

Decreases it

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10
Q

What is the MOA of Ach?

A

Increases the activity of Nitric oxide synthase

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11
Q

What does an increase in nitric oxide synthase lead to?

A

Increase in NO

- Leads to increase cGMP by increasing activity of Guanylate cyclase

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12
Q

What does an increase in cGMP lead to?

A
  • Increase in K+ channel activation

- increase in myosin light chain phosphatase.

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13
Q

What does the activation of K+ channels lead to?

A

Increase efflux of potassium.

- Leads to hyper polarization and thus smooth muscle relaxation

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14
Q

How does the pulmonary vasculature have such a small resistance compared to systemic?

A
  1. Much shorter

2. More capillaries leading to larger radius

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15
Q

What is the typical pulmonary resistance?

A

2mmHg/L/Min

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16
Q

What is the equation for pulmonary blood flow?

A

Vo2/(Cao2-Cvo2)

17
Q

What is the blood flow distribution for zone 1?

A

PA>Part>Pvein

18
Q

When is zone 1 like this?

A

during positive pressure ventilation

  • apex of lung
  • physiologic dead space –> no ventilation
19
Q

What is the blood flow distribution for zone 2?

A

Part>PA>Pvein

20
Q

What is the blood flow distribution for zone 3?

A

Parr>Pvein>PA

21
Q

What determines the blood flow in zone 2?

A

Arterial pressure- alveolar pressure

- towards apex of lung

22
Q

What determines the blood flow in zone 3? What does this resemble?

A

arterial pressure- venous pressure

  • normal systemic circulation
  • base and midline of lungs
23
Q

Does doubling the atmospheric pressure on the capillaries affect flow, for instance while scuba diving?

A

No- relatively all pressure change is the same

24
Q

What is the reason and MOA of hypoxic pulmonary vasoconstriction?

A

Shunting to perfuse areas that are being better ventilated

  • Shut down of K+ channels which leads to hyperpolarizatoin of cell
  • leads to contraction of smooth muscle
25
Q

What are some examples that lead to wet lungs?

A
  • CHF leading to pulmonary HTN- Increase in hydrostatic pressure leads to wet lungs
  • Hypoalbuminemia via kidneys leads to decrease in oncotic pressure
26
Q

What are some of the metabolic functions of the lung?

A
  1. Converts AgI to AgII
  2. Inactivates bradykinin
  3. Removes serotonin
  4. Metabolizes prostaglandins and leukotrienes
27
Q

Is the conversion of AgI to AgII in the lungs unique?

A

Nope

- happens at all endothelium

28
Q

What is unique about extra-alveolar capillaries?

A

They are pulled open by radial traction of the lung parenchyma

29
Q

Hypoxic vasoconstriction are important where else ?

A

High altitudes

Fetus- only 15% of CO goes through lungs

30
Q

What are some potents Vasoconstrictors?

A

Endothelin-1 ET-1

TXA2

Craab 2.5 (8 decks)

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