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38 Cards in this Set
- Front
- Back
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collapsing pressure
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2 x surface tension / radius
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FRC
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volume in lungs after normal expiration (RV + ERV)
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VC
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vital capacity = TV + IRV + ERV
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formula for physiologic dead space
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TV * (arterial pCO2 - expired pCO2)/ arterial pCO2
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what region of lung is largest contributor of dead space
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apex of healthy lung
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what is intrapleural pressure at FRC?
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negative, to prevent pneumothorax
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which form of Hb has low affinity for O2? High affinity?
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taut: low affinity; relaxed: high
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fetal hemoglobin has what affinity for O2? 2,3 BPG?
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high affinity for O2 b/c lower affinity for 2,3 BPG
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what favors T form over R form?
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increased Cl-, H+, CO2, 2-3 BPG, temp
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Methemoglobin
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oxidized form (ferric, Fe3+); increased affinity for CN
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treatment for methemoglobinemia
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methylene blue
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treatment for cyanide posioning
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nitrates to oxidize to methemoglobin; thiosulfate to bind cyanide
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Carboxyhemoglobin
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Hb bound to CO; decreased O2 binding capacity + left shift
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what gases are perfusion limited
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O2, CO2, N2O
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what gases are diffusion limited
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O2 (emphysema, fibrosis), CO
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Diffusion formula
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Vgas = A/T x D(P1-P2)
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pulmonary HTN
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>25 mmHg or > 35 during exercise
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consequences of pulmonary HTN
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atherosclerosis, medial hypertrophy, intimal fibrosis
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primary pulmonary HTN
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inactivating mutation of BMPR2 gene: normally inhibits vascular SM proliferation
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secondary pulmonary HTN
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d/t COPD, mitral stenosis, autoimmune disease, L-->R shunt, sleep apnea, high altitude
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formula for pulmonary vascular resistance (PVR)
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PVR = P pul a - P L atrium / CO
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formula O2 content
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(O2 binding capacity x % saturation) + dissolved O2
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what amt of Hb results in cyanosis
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when deoxygenated Hb > 5 g/dL
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how much O2 can 1 g of Hb bind
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1.34 mL O2
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formula O2 delivery
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O2 delivery = CO x O2 content
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alveolar gas formula
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PAo2 = 150 - PAco2/.8
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Normal A-a gradient
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gradient = PAO2 - PAO2 = 10-15
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causes of increased A-a gradient
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shunting, V/Q mismatch, fibrosis
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V/Q at apex
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3: wasted ventilation
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V/Q at base
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.6: wasted perfusion
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where is ventilation greater? Where is perfusion greater?
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both greater at base
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what is V/Q during aiway obstruction
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approaches 0
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what is a shunt
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airway obstruction
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what is physiologic dead space
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blood flow obstruction
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what is V/Q during blood flow obstruction
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approaches infinity
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3 ways CO2 is transported
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bicarb, bound to Hb @ N terminius of globin, dissolved
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Haldane effect
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Oxygenation of Hb promoites dissociation of H+ from Hb --> shift equilibrium towards CO2 formation
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Bohr effect
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H+ from tissue metabolism shifts curve RIGHT to unload O2
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