Pulmonary Circulation Ventilation/Perfusion Balance

Question 1

Pulmonary vs. Systemic circulation pressures?

Answer 1

120/80

24/9

Question 2

pulmonary edema vs insterstitail adems

Answer 2

PE - when blood leaves both capillary and alveolar endothelium.

IE - Blood only leaves capillary endothelium and accumulates in interstitial space.

Question 3

What are the causes of Edema?

Answer 3

Elevated hydrostatic pressure
Toxin/disease induced increase in capillary permeability
Malnutrition induced - lowering of osmotic pressure
High altitudes
Head injury

Question 4

Where is blood flow the highest in the lungs? why?

Answer 4

The bottom, gravity increases the Pa, and the hydrostatic pressure.

Question 5

Explain pulmonary regional circulation

Answer 5

PA > Pa > Pv - vascular compression - 0 flow sometimes
Pa > PA > Pv - partial compression - pulsatile flow carries
Pa > Pv > PA - vascular distension - red. resistance

Question 6

Increasing Pa or Pv does what to vascular resistance? By what passive mechanisms?

Answer 6

Decreases v. resistance. Think static/kinetic friction

a) recruitment
b) increasing diameter of vasculature

Question 7

Explain pulmonary resistance in terms of lung capacity

Answer 7

+ capillaries with a central emptying tube in center. At higher volume increase diameter of central tube, but also stretches the converging capillaries. This has a U shaped change in pulmonary vascular resistance.

Question 8

Positive End Expiratory Pressure Mechanical Ventilation (PEEP) whats does this do? Give the good and the bad

Answer 8

Mechanical Breathing (positive pressure only); high pressures can compress capillaries, increasing vascular resistance and work done by the heart. But high pressures also can counteract atelectasis (alveolar collapse)

Question 9

Hypoxic Restrictive Vasoconstiction

Answer 9

Circulation is cut of to parts of the lungs, that are not receiving oxygen. This is independent of CNS. Smooth, and is a local mediator of blood flow.