Pulmonary Circulation Lecture 12

Question 1

Effects of hypoxic pulmonary constriction

Answer 1

narrowing of blood vessels to shut off those that are not producing enough oxygen to the blood. Long term effects include hypertrophy of the smooth muscle and pulmonary hypertension; this can lead to right heart failure

Question 2

Effects of pulmonary edema

Answer 2

Narrowing of the airways
hypoxemia <85 mmHg PaO2
decreased compliance (more work to breathe)

Question 3

Causes of edema

Answer 3

Left heart failure can back up the pulmonary circulation
Organ failure of the liver or kidney can back up drainage of the lymphatic system
Acute damage caused by pneumonia or noxious chemicals
ARDS (Adult respiratory distress syndrome) cause increase fluid due to lack of surfactant
Decreased oncotic pressure as a result of anorexia may also cause problems

Question 4

Zones of blood flow in the lungs (3)

Answer 4

Zone 1- Alveolar pressure exceeds both arterial and venous pressure - ergo there is no bloodflow; this condition does not exist in healthy lungs; only in hemorrhagic patients
Zone 2- Pa>PA>Pv - medium flow, normal in the upper 2/3rds of the lung; blood flows during systole BUT not diastole; recruitment of capillaries during exercise happens here
Zone 3- Pa>Pv>PA- continuous flow (Pv>PA); distention happens here; diastolic pressures are greater than alveolar pressures here