Term
| What are Non-Gas Exchange functions of the Pulmonary Circulation? |
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Definition
Filtration - Protects the circulation against embolization of air, thrombi, fluid, and fat
Metabolic - Endothelial cells activate, inactivate and produce compounds that affect the local circulation, systemic circulation, and airways.
Reservoir Function - constriction of pulmonary vessels leads to mobilization of blood into the central circulation |
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Term
| What is an example of Activation-Conversion in the lungs? |
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Definition
| Angiotensin I is activated and converted to Angiotensin II by ACE located on the pulmonary capillary endothelial cells |
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Term
| What is an example of Inactivation in the lungs? |
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Definition
| Bradykinin, serotonin, prostaglandins E1, E2, and F2α and norepinephrine are inacivated by the pulmonary capillaries |
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Term
| What is an example of Production in the lungs? |
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Definition
| Lung tissue injury can induce the pulmonary endothelial cells to release histamine, prostaglandins, leukotrienes, and other inflammatory mediators. These compounds can cause pulmonary arteriole constriction leading to pulmonary hypertension and right heart failure. May also cause constriction of bronchioles leading to perfusion mismatch and hypoxemia. |
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Term
T/F: The pulmonary and systemic circulations have different blood flow per minute.
The systemic circulation has a higher perfusion pressue. |
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Definition
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Term
| What is the Pulmonary Circulation Perfusion Pressure? |
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Definition
| About 15 mmHg. This is the pressure responsible for moving blood from right ventricle to the left atrium. |
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Term
| T/F: Pulmonary vessels have thicker walls, more musculature, and more connective tissue than systemic vessels. |
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Definition
| False. Pulmonary vessels are more compliant. |
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Term
| What percentage of the lung's weight is due to blood? |
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Definition
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Term
| What is the effect on pulmonary arterioles with PAO2 in adjacent alveoli decreases and PACO2 increases? |
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Definition
| The pulmonary arterioles will constrict |
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Term
| What is the effect on pulmonary arterioles with PAO2 in adjacent alveoli incrases and PACO2 decreases? |
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Definition
| The arterioles will dilate |
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Term
| What is the equation for resistance? |
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Definition
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Term
| An increase in Cardiac Output and concomitant increase in pulmonary artery pressure will cause a(n) ____________ in pulmonary vascular resistance (PVR). |
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Definition
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Term
| What are the mechanisms that cause a decrease in PVR following an increase in CO and PAP? |
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Definition
Capillary Recruitment - Increasing CO and PAP will open up more collapsed capillaries leading to decreased resistance.
Capillary Distension - Capillary lumens will distend with higher pressure, further decreasing resistance. |
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Term
| What are the 3 beneficial effects of capillary recruitment? |
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Definition
Reduced velocity of blood flow - this ensures that the time available for capillary diffusion is sufficient
Increased capillary surface area
Maintenance of low resistance and mean pulmonary pressure - |
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Term
| What are the two types of alveolar vessels? |
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Definition
Extra-Aveolar Vessels - arteries and veins that are subjected to pleural pressures
Alveolar Vessels - capillaries that form a network of alveolar walls, which are subjected to alveolar pressures |
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Term
| What is the effect on extra-alveolar and alveolar vessels with regard to inspiration? |
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Definition
Extra-Alveolar - Increase in diameter
Alveolar - Decrease in diameter |
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Term
| Where is pulmonary vascular resistance the lowest? |
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Definition
| At Functional Residual Capacity. |
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Term
| What are some vasoconstrictors of pulmonary vessels? |
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Definition
| Serotonin, Norepinephrine, Histamine, Thromboxane A2, and leukotrienes |
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Term
| What are some vasodilators of pulmonary vessels? |
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Definition
| Adenosine, acetylcholine, prostacyclin (PGI2), NO |
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Term
| T/F: Pulmonary artery hypoxemia and alveolar hypoxia will cause vasoconstriction of the local pulmonary arteries and arterioles. |
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Definition
| True. This is to avert blood away from alveoli that are being insufficiently perfused. |
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Term
| What is Hypoxic Pulmonary Vasoconstriction? |
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Definition
| This will reduce the effect of poorly ventilated alveoli on oxygen and carbon dioxide exchange. This will improve blood oxygenation in lung regions affected by decreased alveolar ventilation. |
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Term
| What is Global Hypoxia and what can cause it? |
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Definition
This is generalized pulmonary arteriole constriction leading to a significant rise in pulmonary vascular resistance (PVR) and Pulmonary Artery Pressure (PAP).
High altitude, end-stage lung disease: emphysema, bronchitis, asthma, cystic fibrosis |
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Term
| What are some factors that fluid movement depends upon? |
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Definition
Hydrostatic Pressure
Colloid Osmotic Pressure
Alveolar Surface Tension
Capillary Permeability
Pulmonary Edema |
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Term
| How does Hydrostatic Pressure effect fluid movement in the lungs? |
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Definition
| Arteriolar pressure and mean capillary pressure favor fluid flux out of the capillary lumen and into the interstitial connective tissue around the alveolus. |
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Term
| Where does outward fluid flux occur in the lungs? |
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Definition
| Occurs in the arteriolar side of the alverolar capillary bed. |
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Term
| Where does inward fluid flux occur in the lungs? |
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Definition
| On the venous side of alveolar capillary bed |
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Term
| What decreases the alveolar surface tension? |
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Definition
| Surfactant. Loss of surfactant leads to increased fluid in the interstitial space. |
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Term
| What is the effect of increased Capillary Permeability on fluid flux in the lung? |
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Definition
| Pulmonary capillary is normally permeable to small molecules such as water and electrolytes, but impermeable to proteins. Increased capillary permeability will lead to diffusion of proteins and increased interstitial fluid retention. |
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Term
| What occurs when there is accumulation of fluid in the interstitial and alveolar space due to capillary filtration exceeding re-absorbtion. |
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Definition
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Term
| What are some causes of Pulmonary Edema? |
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Definition
1. Left Ventricular Failure
2. Damage to Type II pneumocytes decreasing surfactant production
3. Decreased colloid osmotic pressure
4. Diffuse lung injury |
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Term
| T/F: Diffusion is usually the cause of hypoxemia in patients with significant pulmonary disease |
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Definition
| False. Since total surface area is large and membrane thickness is so small, diffusion occurs very easily. |
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Term
| What is used to normally measure the lung's diffusion constant or capacity? |
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Definition
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