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24 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What are 4 functions of the lung and pulmonary circulation?
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1. Blood filtering
2. A metabolic organ 3. A blood reservoir 4. Gas exchange |
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The main metabolic function of the lung is?
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Converting angiotensin 1 to angiotensin 2 using ACE(angiotensin converting enzyme)
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What is the lung a reservoir for?
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It contains 500ml of blood that stabilizes the left ventricle stroke volume when standing up quickly.
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Why is gas exchange better in some parts of the lungs versus others?
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Because when standing up blood is more affected by gravity than air, and there is a mismatch of ventilation and perfusion. This means that the best gas exchange will occur at the bottom of the lung because more blood is there.
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Shunts:Left to Right, and Right to Left
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Left to Right Shunt(Arterial blood pumps into Venous blood)
Right to Left(Venous blood drains into Arterial blood) |
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What are 2 normal anatomical shunts(R to L)?
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1. Bronchial circulation is where the bronchial veins drain into the pulmonary veins(mixed venous O2).
2.Coronary circulation where the Thebesian veins(left heart) drain into the left ventricle. |
Bronchial and Coronary
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Why are abnormal shunts bad?
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R-L shunts can dump deoxygenated O2 into oxygenated blood and lower the PO2.
L-R shunts can increase pulmonary pressure. |
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What is the mean driving pressure of the pulmonary circulation and compare it to systemic circulation?
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10mmHg compared to 91mmHg in systemic circulation. This shows that there is a much lower vascular resistance in pulmonary circulation.
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How is left atrial or Wedge pressure measured?
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A catheter is inserted into a peripheral vein and advanced through to the heart. The catheter goes to the pulmonary artery and a balloon is inflated. The blood flow stops and the pressure is the left atrial pressure(LAP).
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What can cause elevated left atrial pressure(LAP)?
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Mitral stenosis or pulmonary edema.
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What is systolic pressure?
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The peak pressure in the arteries when the ventricles contract, normal is 115 Torr in adults.
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What is diastolic pressure?
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The lowest pressure in the resting phase of the cardiac cycle, about 75 Torr in healthy adults.
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What is the normal pulmonary blood volume?
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It is actually dynamic and changes easily with intrathoracic pressures. normally it's about 500ml in the lungs and 70-100ml in the lung capillaries.
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What is pulmonary vascular resistance controlled by?
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It is controlled by lung volume, cardiac output, and local chemical control.
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Relationships between lung volume and pulmonary vascular resistance(PVR)?
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1. At low lung volumes alveolar blood vessels compress and form a positive pressure against blood from the heart.
2. At high lung volumes the alveoli compress and the blood vessels also increase resistance. 3. So the PVR is high at low and high lung volumes. |
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Relationship between cardiac output and PVR?
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Exercise can cause and increase in cardiac output which actually decreases the PVR because of recruitment of extra capillaries to get more blood flow through easier.
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Recruitment
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Relationship between lung hypoxia and PVR?
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Low PO2 in the alveoli can cause vasoconstriction to increase blood flow due to increased pressure and velocity thereby increasing PVR. If you increased the cardiac output here you would just be wasting a lot of effort cause there's not enough O2 there anyways.
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If you increased the cardiac output here you would just be wasting a lot of effort cause there's not enough O2 there anyways.
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4 causes of pulmonary edema
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1. Increased hydrostatic pressure due to heart failure.
2. Increased capillary permeability 3. Increased surface tension 4. decreased colloid osmotic pressure |
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Increased hydrostatic pressure and Edema
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Mitral stenosis and congestive heart failure result in an increase in left atrial pressure. This means the lung circulation is backing up. The edema happens about 20 Torr.
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Cardiogenic edema
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Increased capillary permeability and edema
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Non cardiogenic edema. If there is damage to the capillary or alveolar endothelium, plasma proteins may leak into the interstitial space and alveoli. The water then follows by osmosis and fluid is there.
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High surface tension and edema
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Surfactant can be reduced if edema fluid enters the alveoli. The liquid causes a higher surface tension. This leads to more fluid movement into interstitial space and alveoli.
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Fluid has a higher surface tension than surfactant.
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Decrease plasma protein and edema
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Decreases in colloid osmotic pressure can result in pulmonary edema because the water will flow out of the plama and into the lungs.
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Other causes of edema
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Impaired lymphatic drainage, high altitude, and drowning.
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Pleural effusion
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edema of the plural cavity.
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