8. Special Circulations Flashcards Preview

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Flashcards in 8. Special Circulations Deck (13)
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1
Q

The metabolic needs of the lungs are met by which circulation?

A

Bronchial circulation

2
Q

What is the optimal ventilation perfusion ratio?

A

0.8

3
Q

Alveolar hypoxia leads to what happening to the pulmonary vessels and why is this beneficial?

A

Vasoconstriction, this allows optimal gas exchange as less well ventilated alveoli are less well perfused

4
Q

Chronic hypoxic vasoconstriction can be caused by what?

A

Altitude

Emphysema

5
Q

Chronic hypoxic vasoconstriction can cause what condition?

A

Right ventricular failiure

6
Q

Why is pulmonary oedema unlikely to occur normally?

A

Pulmonary capillary pressure is low hence hydrostatic is small relative to oncotic pressure so little fluid leaves

7
Q

What can increase pulmonary pressure?

A

If left atrial pressure rises due to:
Mitral valve stenosis
Left ventricle failiure

8
Q

What is the affect of exercise on pulmonary blood flow?

A

Increased cardiac output
Vasodilatation of pulmonary system
More O2 exchange
System stable as demand met

9
Q

What is Cushing’s reflex?

A

Where impaired blood flow to the brain is dealt with by increasing sympathetic vasomotor activity increasing arterial blood pressure to maintain cerebral flow

10
Q

The filling of the coronary circulation occurs mostly during which part of the cardiac cycle and why?

A

Diastole

Pressure decreases due to heart relaxation

11
Q

Coronary endothelia produce which chemical to cause vasodilation to ensure blood flow?

A

NO

12
Q

Increasing core temperature causes what to happen in cutaneous circulation to dissipate heat?

A

Artereovenous anastamoses open
Increased blood flow to skin
Heat dissipated via shunting to venous plexus

13
Q

The pulmonary circulation is supply driven, what does this mean?

A

Must accommodate all of cardiac output