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22 Cards in this Set
- Front
- Back
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Functions of CV System |
1) Meet body's metabolic needs - deliver O2 (12 fold during exercise) and remove CO2/metabolic byproducts 2) Maintain blood flow to brain and heart 3) Maintain blood pressure to drive renal filtration 4) Distribute nutrients, immune cells, hormones 5) Control core temperature |
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Importance of constant MAP |
Allows tissues to regulate own flow by adjusting resistance |
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Types of vessels |
Large arteries - conduit vessels Arterioles - resistance vessels Capillaries - exchange vessels Veins - return vessels |
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Cardiac output |
Flow out of aorta. CO (L/beat) = HR (beat/min) * SV (L/beat) |
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Fick's Law |
VO2 = deltaAVO2 * CO VO2 - rate of O2 consumption deltaAVO2 - difference in O2 content between arterial and venous system For individual tissue, replace CO with flow (q) and use deltaAVO2 for tissue. |
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Pressure |
Force/Area Measured in mmHg Total pressure includes hydrostatic pressure and other (respiratory, muscular, etc) |
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Hydrostatic Pressure |
P = pgh, p = density |
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Flow vs Flow Velocity |
Flow Q = Volume/Time - constant throughout system Flow velocity V = Q/A - decreases in wide part |
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Ohm's Law for Fluid Flow |
V = IR deltaP = Q * R, Q = flow, R = resistance |
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Calculating total hydraulic resistance |
Series - sum individual resistances Parallel - 1/RT = 1/R1 + 1/R2 + ... + 1/Rn |
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Poiseuille's Equation - Effect of tube length, radius, and viscosity on flow |
Q = (Pi-Po) * pi*r^4 / 8nl = deltaP / R R = 8nl/pi*r^4 Flow is directly proportional to r and deltaP and inversely proportional to viscosity and length. |
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Laminar vs Turbulent Flow |
Laminar flow - silent with parabolic distribution of flow velocity. Obeys Poiseuille's equation. Turbulent flow - Noisy with chaotic distribution of flow velocity. |
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Compliance |
Ability to distend vessel based on pressure. Ratio of change in volume per unit change in pressure. Analogous to capacitance C = deltaV / deltaP = deltaV / pgdeltah Short tubes have high compliance |
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Pulse pressure |
Systolic pressure (SBP) - diastolic pressure (DBP) |
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Mean arterial pressure |
(1/3 * Pulse Pressure) + Diastolic Pressure |
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Taking blood pressure |
Pump sphingomometer until brachial artery is occluded. Lower pressure gradually so artery opens briefly, find diastolic pressure when sound goes away. |
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Mean right atrial pressure |
MRAP = CVP |
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Total peripheral resistance |
Total resistance of all vessels between left ventricle and right atrium. Small arteries, arterioles, precapillary sphincters. R = deltaP / Q Peripheral Resistance Unit (PRU) = mmHg/mL/sec |
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Systemic circulation model |
CO = (MAP-MRAP) / TPR If MRAP = 0, CO = MAP/TPR MAP = CO * TPR = (HR * SV) * TPR |
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Pulmonary circulation model |
CO = (MPAP - MLAP) / Total pulmonary resistance Pattern of TPR and compliance determines dynamic changes in blood pressure (time constant) |
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Arterial system characteristics |
No resistance Low compliance High pressure (MAP) Conduit vessels little of total blood volume Afterload determined by compliance |
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Venous system characteristics |
No resistance High compliance Low pressure (CVP) CVP = MRAP Much of total blood volume Preload - filling pressure of heart |
