SFOS 23

• Systolic - 25 mmHg
• Diastolic - 10 mmHg

Estimate of left atrial pressure

Venous flow

Flow through top portion of lung only during systole when pressure is high enough

No flow if alveolar P always greater than pulmonary arterial pressure

• Recruitment of closed capillaries
• Distention of open capillaries
• Elevate pulmonary arterial pressure to increase flow

• Collapse of lung tissue
• Results in blood vessel collapse

• Hyperexpanded alveoli crush capillaries
• Increase pulmonary resistance

• If gas in lungs has low O2 levels, blood vessels constrict
• Directs blood to well-oxygenated regions

• Vasocontriction of whole lung in hypoxic environment (high altitude)
• Results in pulmonary hypertension

• Keeps lungs contricted, limiting flow
• Release at birth