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Block 2 Exam 3 > Pulmonary Circulation: Week 7 > Flashcards

Pulmonary Circulation: Week 7 Flashcards

1
Q

What two structures do the right pulmonary veins pass behind?

A
  1. right atrium

2. superior vena cava

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2
Q

What structure do the left pulmonary veins pass in front of?

A

descending thoracic aorta

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3
Q

Primary site of gas exchange

A

pulmonary capillaries

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4
Q

What is the normal pulmonary artery pressure?

A

15mmHg/8mmHg

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5
Q

Blood pressure varies with the height of the lung. What is the pressure at the apex? What is the pressure at the base?

A

12mmHg; 36mmHg

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6
Q

What percentage of pulmonary vascular resistance is at the level of the capillaries?

A

35-45%

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7
Q

What does low pre-capillary resistance lead to? What happens in pulmonary arterial hypertension?

A

pulsatile motion in the microvascular bed; this motion is lost in severe pulmonary arterial hypertension

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8
Q

What is the transit time across the microcirculation?

A

0.5-1 sec

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9
Q

Equation for pulmonary vascular resistance. How does pulmonary vascular resistance compare to systemic vascular resistance?

A

PPA - PPV / Pulmonary Blood Flow

About 1/10th of systemic vascular resistance, because there are no arterioles to regulate blood flow.

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10
Q

As pressure in the left atrium increases, pulmonary vascular resistance will no longer decrease as a result of increasing PPA. Why?

A

The vascular bed is fully distended.

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11
Q

Capillaries are near atmospheric pressure (alveolar pressure). How?

A

Because of surfactant

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12
Q

Pressure decreases further when lung expands, causing radial traction. What two things occur?

A
  1. Pulls open vessels

2. Reduces pressure

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13
Q

Pulmonary vascular resistance can be decreased by three mechanisms. What are they?

A
  1. Recruitment (opening of previously closed capillaries
  2. Distension (increase caliber of already open capillaries
  3. Expansion of lung volume
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14
Q

What does pulmonary artery wedge pressure measure? What are the normal values?

A

Measures static fluid pressure in the pulmonary circuit. Reflects left atrial pressure and estimates total body fluid balance. Normal values range from 8-12mmHg.

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15
Q

Describe the general pattern of blood flow from base to apex in the lung.

A

From base to apex, there is a decrease in flow.

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16
Q

Discuss the relationships of alveolar pressure, pulmonary arterial pressure, and pulmonary venous pressure at the apex of the lungs (zone 1).

A

Alveolar pressure > pulmonary arterial pressure > pulmonary venous pressure

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17
Q

Discuss the relationships of alveolar pressure, pulmonary arterial pressure, and pulmonary venous pressure at the base of the lungs (zone 3).

A

Pulmonary arterial pressure>pulmonary venous pressure>alveolar pressure

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18
Q

Discuss the relationships of alveolar pressure, pulmonary arterial pressure, and pulmonary venous pressure at the midsection of the lungs (zone 2)

A

Pa > PA > Pv

19
Q

In the supine position, what happens to apical blood flow? What happens to basal blood flow?

A

Apical blood flow increases; basal blood flow stays the same

20
Q

What happens to apical blood flow during exercise? What happens to basal blood flow?

A

Apical blood flow increases; basal blood flow increases

21
Q

What is the main reason for regional blood flow differences?

A

Hydrostatic pressure

22
Q

In zone 1 of the lungs, the apex is ventilated but not perfused. This is referred to as?

A

Dead space ventilation

23
Q

What occurs during dead space ventilation?

A

Capillaries are flattened due to increased alveolar pressure

24
Q

What determines blood flow in zone 2?

A

Blood flow determined by difference between Palveolar and Parterial. This is called the waterfall effect.

25
Q

What determines blood flow in zone 3?

A

Blood flow determined by usual arterial - venous pressure

26
Q

Physiological phenomenon in which pulmonary arteries constrict in the presence of hypoxia (low oxygen levels) without hypercapnia (high carbon dioxide levels), redirecting blood flow to alveoli with a higher oxygen content

A

Hypoxic vasoconstriction

27
Q

At what level of PO2 is hypoxic vasoconstriction most responsive?

A

PO2 alveolar less than 70mmHg

28
Q

What happens at high altitude? What happens to pressure in the pulmonary arteries?

A

Generalized vasoconstriction; increased pressure in pulmonary arteries

29
Q

Factors that inhibit hypoxic vasoconstriction

A 
CO
Increased pulmonary vascular resistance
Acidosis/alkalosis
Ca+ channel blockers
Inhaled anesthetics
30
Q

Where does fluid leaking from capillaries go?

A

To the interstitium of alveolar walls via perivascular and peribronchial lymph nodes. May cause interstitial edema.

31
Q

What happens when the capacity of the lymphatics is exceeded?

A

Alveolar edema. Fluid pours into alveoli and interferes with gas exchange.

32
Q

Increased intracranial pressure leading to increased pulmonary capillary pressure

A

Neurogenic pulmonary edema

33
Q

Accumulation of proteinaceous fluid in the alveoli due to a number of causes

A

Adult respiratory distress syndrome

34
Q

Causes of ARDS

A
  1. severe trauma
  2. sepsis
  3. pancreatitis
  4. aspiration pneumonia
  5. community-acquired pneumonia
35
Q

Treatment for ARDS

A

low tidal volume ventilation

36
Q

Variant of ARDS

Occurs with massive blood product transfusion, most commonly fresh frozen plasma

A

Transfusion related acute lung injury (TRALI)

37
Q

What’s the proposed mechanism for TRALI?

A

Mechanism thought to be development of anti-granulocyte antibodies which then attack the recipient’s granulocytes, and initiate an inflammatory response in the pulmonary capillaries

38
Q

2 other functions of pulmonary circulation

A
  1. reservoir for blood

2. filtration

39
Q

One metabolic function of the lungs includes the activation of what?

A

Angiotensin I to Angiotensin II

40
Q

One metabolic function of the lungs includes the inactivation of what?

A

Bradykinin, serotonin, prostaglandins, norepi, arachidonic acid

41
Q

The lung converts arachidonic acid to what two things?

A
  1. leukotrienes (via lipoxygenase)

2. prostaglandins (via COX)

42
Q

What two things do all prostaglandins cause?

A
  1. platelet aggregation

2. bronchoconstriction in asthma

43
Q

What does prostaglandin E2 do?

A

Relaxes patent ductus arteriosus in fetus

Block 2 Exam 3 (19 decks)

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