HRR: pulmonary circulation Flashcards
What is the approximate volume of the lungs?
500 mL
What is the capillary volume in the lungs?
75 mL
What are the circulations in the lungs?
Pulmonary and bronchial
Describe pulmonary circulation.
It involves the reoxygenation of blood delivered from the right heart. It is 100% of cardiac output.
Which circulation in the lungs is involved in generation of pleural fluid?
Pulmonary
Describe bronchial circulation.
Involved in the oxygenation of bronchioles and is about 2% of cardiac output.
Pulmonary circulation is a ___ pressure, ___ resistance, and ___ compliance circulation.
Low, low, high
How are extra alveolar vessels impacted by alveolar pressure?
They’re not!
How are extra alveolar vessels impacted by intrapleural/interstitial pressure?
Their caliber is impacted by lung volumes; a higher volume decreases intrapleural pressure, which will increase diameter of the vessels.
How are alveolar vessels impacted by alveolar pressure?
A high alveolar volume increases alveolar pressure and causes a decreased diameter of the vessels.
As pulmonary artery pressure goes up, what happens to resistance?
It goes down! This is due to distension and recruitment of pulmonary capillary beds.
What is passive regulation?
The capacity of pulmonary capillaries to adjust to changes in flow and pressure while keeping resistance low.
What is active regulation?
Local hypoxia causes vasoconstriction, allowing for more blood to be sent to areas of oxygenation. The same process with generalized hypoxia causes increased PVR, PH, and right heart hypertrophy. This occurs at small arteries and arterioles.
What is the primary factor of active regulation?
Alveolar oxygen tension
What is a main vasodilatory in pulmonary vasculature?
Low PACO2
What is a main vasoconstrictor in pulmonary vasculature?
High PACO2
Which zone of the lung gets the most blood?
Zone 3 (lower lung)
Which zone of the lung gets the most ventilation?
Zone 3 (lower lung)
Describe an anatomic shunt in the pulmonary vasculature.
Venous blood bypasses oxygenation at the capillary and gets directly into arterial circulation.
Why does pulmonary edema occur in HF?
Normally, filtration is favored in the lung vasculature. In normal conditions the lymphatic system can handle this to prevent excess fluid in the lungs. However, increased LV pressure causes a back pressure into the atrium, then the pulmonary veins, then the capillaries. This causes even more filtration to account for the pressure increase, and the lymphatics can’t handle the volume.
