Term
| name two mechanisms explaining why pulmonary vascular resistance gets smaller as pressure within pulmonary circulation rises: |
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Definition
| 1. recruitment 2. distension |
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Term
| vascular resistance of extra-alveolar vessels is (high/low) at large lung volumes and (high/low) at low lung volumes |
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Definition
| low at large lung volumes, high at low lung volumes |
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Term
| drugs that are effective vasoconstrictors |
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Definition
| serotonin, histamine, norepinephrine |
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Term
| drugs that relax smooth muscle in pulmonary circulation: |
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Definition
| acetylcholine, isoproterenol |
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Term
| Equation for calculating O2 consumption per minute: |
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Definition
Oxygen consumption is equal to amount of oxygen taken up by blood in lungs: VO2dot = Qdot(CaO2-CvO2)
OR: Qdot = VO2dot/(CaO2-CvO2) |
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Term
| the pulmonary artery carries (mixed venous or arterial) blood |
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Definition
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Term
| how do you explain the distribution of blood flow in the lung (blood flow decreases almost linearly from bottom to top)? |
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Definition
| hydrostatic pressure: difference in pressure between the bottom and top of a lung 30 cm high will be ~30 cmH2O |
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Term
| What factors govern fluid exchange in and out of capillaries? What is the equation? |
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Definition
forces pushing fluid out: capillary hydrostatic pressure minus capillary pressure in the interstitial fluid (Pc-Pi); force pulling fluid in: colloid osmotic pressure of proteins in blood minus proteins in interstitium: sigma(PIc-PIi)
net fluid out = K[(Pc-Pi)-sigma(PIc-PIi) |
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Term
| What is the pressure difference in the pulmonary circulation versus the systemic pressure? |
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Definition
| pressures in pulmonary circulation are very low: PA - right atrium pressure = 15-5 =10; pressure difference in systemic circ.: MAP - left atrium = 100 - 2 = 98 mmHg |
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Term
| equation for vascular resistance: |
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Definition
| (input-output pressure)/blood flow |
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Term
| optimal (lowest) pulmonary vascular resistance occurs at: |
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Definition
| functional residual capacity (FRC) |
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Term
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Definition
| Palveolar > Parterial > Pvenous; NOT NORMAL; arterial pressure lower than alveolar so no blood flows; may occur during hemorrhage or positive-pressure ventilation; is ventilated but unperfused lung |
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Term
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Definition
| Parterial > Palveolar > Pvenous; blood flow determined by by arterial-alveolar pressure difference |
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Term
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Definition
| Parterial > Pvenous > Palveolar; venous pressure exceeds alveolar pressure; blood flow determined by the arterial-venous pressure; increasing blood flow involves distension of capillaries |
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Term
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Definition
| collapsed lung as bases; high resistance to blood flow in extra alveolar vessels |
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