Pulmonary Blood Flow Flashcards
What supplies blood to the lung? What percentages of L and R ventricular output does the lung receive?
Bronchial circulation through bronchial arteries and through pulmonary circulation; 2% of L and 100% of R
To what point in the tracheobrochial tree do bronchial arteries run?
Down to terminal bronchioles
How do respiratory bronchioles receive oxygen and nutrients?
They get oxygen directly from the air and nutrients from pulmonary circulation
How does bronchial drainage occur?
Part drains into the azygous v. and part drains directly into the pulmonary vein (normal anatomic shunt)
If the left side of the heart begins to out perform the right side, what will occur? The right outperforming the left?
Peripheral edema; Pulmonary edema
What is the resistance of pulmonary blood flow relative to systemic resistance to blood flow? Why?
Pulmonary blood flow has lower resistance because vessels in pulmonary circulation are more extensible
Where does the most resistance to blood flow occur in pulmonary circulation?
Capillaries
In which capillaries is flow pulsitile? Non-pulsitile?
Pulsitile in pulmonary circulation and non-pulsitile in systemic circulation
What is the equation for determining pulmonary vascular resistance?
resistance= (Mean pulmonary artery pressure- mean left atrial pressure)/ pulmonary blood flow
True or False: Most of the time pressure and flow determine the resistance of pulmonary circulation
True
What is the approximate ratio of capillaries to alveoli?
900: 1
What layers must a molecule of oxygen pass through before it can combine with hemoglobin?
Alveolus, thin layer of surfactant, alveolar endothelium, interstitial space, capillary endothelium, plasma, RBC membrane
What two types of vessels need to be considered in pulmonary vascular resistance?
Extra-alveolar and alveolar vessels
When inspiring deeply, what happens to the resistance in the extra-alveolar vessels? the alveolar vessels?
Extra-alveolar vessel resistance decreases and alveolar resistance increases
What makes the extra-alveolar vessels open during a deep breath?
Traction from filled alveoli, and intrapleural pressure is getting more negative and so transmural pressure gradient is increasing
Which pulmonary vessels increase in resistance during inspiration from FRC to the TLC? From the FRC to the RV?
Alveolar vessels; Extra-alveolar vessels
What is the relationship between blood flow and pulmonary vascular resistance?
Increased blood flow decreases pulmonary vascular resistance
What are the two mechanisms by which increased mean pulmonary artery pressure may decrease pulmonary vascular resistance?
Distension and recruitment
What is the effect of increased and decreased lung volume on pulmonary vascular resistance?
Increased
What is the effect of increased blood pressure or increased cardiac output on pulmonary vascular resistance?
Decreased
What is the effect of sympathetic stimulation on pulmonary vascular resistance?
Increased resistance
What molecules increase pulmonary vascular resistance?
Norepinephrine, epinephrine, alpha-adrenergic agonists, thromboxane, PGF2alpha, PGE2, angiotensin, endothelin, and histamine
What compounds decrease pulmonary vascular resistance?
ACh, beta-adrenergic agonists, PGE1, prostacylin, NO, and brandykinin
What region of the lung has the most blood flow when upright? Why?
There is more blood flow in lower parts of the lung because there is greater pressure at the bottom and therefore more recruitment and distension
What serves as the downstream pressure in pulmonary blood flow in zone 2 of the lung?
Alveolar pressure
In what zone of the lung is both pulmonary artery and pulmonary vein pressures greater than alveolar pressure?
Zone 3
Roughly what percent of the lung should be zone 1 in a young, healthy adult?
Should be no zone 1 because that is alveolar dead space
What is HPV in the context of pulmonary physiology? What is it?
Hypoxic Pulmonary Vasoconstriction- Pulmonary blood pressure increased and vessels constricted in response to hypoxia
What is the effect of hypoventilation on arterial O2 and CO2?
Hypoventilation decreases O2 and increases CO2
How does HPV help to maintain V/Q?
HPV increases the resistance to blood flow to hypoventilated alveoli- this diverts blood flow away from the hypoventilated alveolus to better ventilated alveoli
