Question | Answer |
What is the organization of pulmonary circulation? | pulmonary artery, branch with airways, mesh of capillaries at the respiratory bronchioles, pulmonary venules, and pulmonary veins |
What is the flow and pressure of pulmonary circulation? | high flow, low pressure |
What happens to alveolar vessels when they are exposed to high alveolar pressure? | contract |
What happens to alveolar capillaries when the alveolar pressure is low? | the alveolar capillaries dilate |
What inspiration do to extra-alveolar vessels? | pulls them open by radial traction |
What is the only organ to receive all of the cardiac output? | lungs |
Why is there little smooth muscle in the lung? | only enough to direct blood to all areas of the lung. |
What determines blood flow in the lung? | passive hydrostatic forces |
What are the two types of vessels in the lung? | alveolar vessels (capillaries exposed to alveolar gases) and extra-alveolar vessels |
What determines the diameter of extra-alveolar vessels? | lung volume |
What determines the caliber of alveolar vessels? | balance between internal and alveolar pressures |
Which vessel can collapse if alveolar pressure is large enough? | pulmonary capillaries |
What is pulmonary vascular resistance compared to systemic vascular resistance? | pulmonary vascular resistance is 1/10th of the systemic vascular resistance |
What will happen to pulmonary vascular resistance if the arterial or venous pressure increases? | pulmonary vascular resistance decreases |
Why does pulmonary vascular resistance reduce? | recruitment and distension of other pulmonary capillaries |
When does pulmonary vascular resistance increase? | with low or high lung volumes |
Why does pulmonary vascular resistance increase at high lung volumes? | the high volumes put a lot pressure on the capillaries stretching them increasing resistance |
Why does pulmonary vascular resistance increase at low lung volumes? | the resistance is from the extra alveolar vessels because there is less radial traction to open up these vessels. |
Where is pulmonary blood flow grater? | lung base |
Where is the greatest distension of capillaries? | Zone 3 (base) |
Where are the vessels most compressed? | zone 1 (apex) |
What is hypoxic vasoconstriction? | blood flow in the lung is directed away from the hypoxic area of the lung. Usually is regional |
What happens in generalized hypoxia? | elevates pulmonary pressure by large areas of hypoxia which results in edema. |
Why is keeping the alveolar walls problematic in keeping them dry? | they are very thin |
What causes fluid leakage? | Hydrostatic pressure and the surface tension |
What causes fluid to stay in the capillaries? | colloid osmotic pressure and lymph drainage |
Where is fluid in early edema? | engorgement of interstitial spaces |
Where is fluid in late edema? | fluid in alveoli |
What are the metabolic functions of the pulmonary system? | conversion of angiotension I to Angiotension II, serotonin uptake and removal of Norepi, leukotrienes and prostaglandins |