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12 Cards in this Set

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What are the 4 differences between pulmonary and systemic arteries/veins?
Wall thickness greater in systemic.
Compliance greater in pulmonary.
Pressures greater in systemic.
Volumes - only 10% in pulmonary
Where is the peak pulmonary pressure? Where does the difference in pulmonary pressures disappear btwn systole and diastole?
Peak pulmonary pressure at heart.
Difference dissapears at the pulmonary capillaries.
What is zone 1, zone 2, zone 3?
Zone 1- no flow because alveolar pressure is greater than arterial pressure.

Zone 2- Intermittent flow because systolic arterial pressure is higher than alveolar pressure

Zone 3 - Continuous flow because arterial pressure remains greater than alveolar always.
How does pulmonary vascular resistance change as lung volume changes?
At RV, alveolar vessels are spherical. At TLC, they become stretched thin, resistance increases.

But for extraalveolar vessels, the opposite is true. At low lung volumes they are small, and at high lung volumes they are large.

The net result is that PVR is lowest in between the two.
In the upright position, how does blood flow change from bottom to top of lung?
Flow is greater in the bottom of the lung. (Top of lung has lower perfusion pressures). At the very bottom there is a small drop off in flow- due to positive pleural pressure compressing vasculature.
Is gravity the sole determinant of regional differences in lung perfusion?
Remember that lung perfusion generally increases as you go down the lung. This is not solely due to gravity because theres isogravitational plane variations in perfusion thought to be caused by SEQUENTIAL BRANCHING OF PULMONARY VESSELS.
How does hypoxia affect pulmonary vascular resistance?
How does pH play a role in this?
As inspired PO2 is decreased, PVR increases, which is bad!
At lower pHs, this effect becomes even worse.
What happens if you have an underventilated alveolus in terms of capillary flow?
The blood supply to the capillary decreases, diverting the blood to a well ventilated alveoli.
What occurs to maintain a long pulmonary transit time during conditions of increased flow (exercise)
Capillaries expand to increase lung volume; each unit of blood will remain in the lung for a longer period of time.
How do N2O, O2, and CO differ in how they will reach equilibrium between alveoli and capillaries?
N2O is not bound in the blood so its partial pressure rapidly rises to its partial pressure in the alveoli. CO is rapidly taken up by RBC, so its partial pressure only reaches a fraction of its partial pressure in the alveoli. O2 is in the middle of the two.
What factors keep the lungs dry?
Hydrostatic and osmotic pressure drive water into the pulmonary interstitial space, which is then drained by the lymphatic pump.
Why does pulmonary edema not occur until left atrial pressure has increased to about 25 mmHg?
High compliance in pulmonary vasculature prevents this.
Lymphatic pump removes excess water.