Pulmonary CIrculation

Question 1

Pulmonary Circulation System

Answer 1

-Normally low resistance and high compliance

Question 2

Effects of pO2 and pCO2

Answer 2

• Exert opposite effects on pulmonary and systemic circulation
• Decreased pA-O2 causes hypoxic vasoconstriction to shift blood flow away from poorly ventilated regions of the lung

Question 3

Diffusion

Answer 3

Vgas=A/T X Dk(P1-P2)
	A is area
	T is thickness
	Dk(P1-P2) is partial pressure differential
A is decreased in emphysema
T is increased in pulmonary Fibrosis

Question 4

Pulmonary Hypertension

Answer 4

• Normal pulmonary artery pressure: 10-14mmHg
• Pulmonary HTN is >25mmHg or >35mmHg during exercise
• Results in atherosclerosis, medial hypertrophy, and intimal fibrosis of pulmonary arteries

Question 5

Primary Pulmonary HTN

Answer 5

• Due to inactivating mutation in BMPR2 gene
• Normally functions to inhibit vascular smooth muscle proliferation
• Poor prognosis

Question 6

Secondary Pulmonary HTN

Answer 6

• Causes:
  
  • COPD: destruction of lung parenchyma
  • Mitral stenosis: Increased resistance increases pressure
  • Recurrent thromboemboli: decreased area of vascular bed
  • Autoimmune: inflammation->intimal fibrosis->medial hypertrophy
  • LT-RT shunt: shear stress->endothelial injury
  • sleep apnea/altitude: hypoxic vasoconstriction
• Can lead to severe respiratory distress
  
  • Then cyanosis and Right heart hypertrophy
  • cor pulmonale-> RT ventricular failure

Question 7

Pulmonary vascular resistance

Answer 7

PVR=(Ppulmonary artery-Plt atrium)/cardiac output
Delta P=Q x R
R=delta P/Q
Resistance= 8nl/pi r^4