27 Questions
What happens to alveolar capillary walls when blood volume inside increases?
They distend
At high lung volumes, what happens to extra-alveolar vessel resistance to blood flow?
It decreases
What is the effect of increased cardiac output on pulmonary vascular resistance?
It decreases pulmonary vascular resistance
What is the primary cause of decreased resistance to pulmonary blood flow during exercise?
Increasing blood flow to the lungs
What is the main factor contributing to a decrease in pulmonary vascular resistance when pulmonary capillary blood volume increases?
Distention of open vessels
At what lung volume is pulmonary vascular resistance usually lowest?
At functional residual capacity (FRC)
What is the main reason why edema fluid accumulates in the interstitium before the alveoli?
The pulmonary capillary endothelium is more permeable to water than the alveolar epithelium.
How does the resistance of pulmonary vessels compare to systemic circulation?
Pulmonary vessels have 1/10 the resistance of systemic circulation.
Which vessels of pulmonary circulation are analogous to the vessels where 70% of resistance in systemic circulation is found?
In distributing vessels
How do pulmonary vessels compare to systemic vessels in terms of compliance?
Pulmonary vessels are more compressible than systemic arteries.
How many pulmonary veins normally enter the left atrium?
Four veins
What type of vessels are considered exchange vessels in the pulmonary circulation?
Pulmonary capillaries
In which zone of the lung does continuous blood flow normally occur?
Zone 3
What is the characteristic of Zone 1 of the lung?
Alveolar dead space
How is pulmonary capillary wedge pressure (PCWP) estimated?
By thermal dilution technique
In which lung zone would capillary pressure never exceed alveolar pressure?
Zone 1
What is the function of the Swan-Ganz catheter in measuring PCWP?
To estimate PCWP by being floated into the pulmonary artery
How does positive pressure ventilation (PPV) affect pulmonary blood flow?
Decreases pulmonary blood flow by decreasing RV preload
What effect does intrathoracic pressure have on venous return during mechanical ventilation?
Decreases venous return by compressing great veins
What happens to alveolar pressure during inspiration in positive pressure ventilation (PPV)?
Alveolar pressure increases
How does positive alveolar pressure during mechanical ventilation affect Zone 1?
Increases Zone 1
What role does positive end-expiratory pressure (PEEP) play in intrapulmonary shunting during ventilation?
Decreases intrapulmonary shunting
How does positive pressure ventilation affect total thoracic blood volume?
Decreases total thoracic blood volume
Which of the following situations would be expected to lead to an increase in the amount of the lung under zone 1 conditions?
Positive-pressure ventilation with positive end-expiratory pressure (PEEP)
Which of the following situations would be expected to decrease pulmonary vascular resistance?
Moderate exercise
What might be expected to contribute to the formation of pulmonary edema?
Overtransfusion with saline
What causes active vasoconstriction in pulmonary circulation according to the text?
Alveolar hypoxia or atelectasis
Test your knowledge on the three zones of pulmonary blood flow in the lungs demonstrated through experiments on excised lungs of experimental animals. Learn about the characteristics and parameters of Zone 1, where there is no blood flow and capillary pressure is never greater than alveolar pressure.
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