PNB 2265 Lecture Notes - Lecture 6: Mean Arterial Pressure, Superior Vena Cava, Heart Rate
16 Aug 2018
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Document Summary
The structure of blood vessels dramatic affects how blood flows through: both speed and force needed to push the blood. Affected by the physical properties of blood: hemodynamics. Blood vessels change and that change determines how blood flows through them. Physical factors affecting blood flow through arteries and veins. Pressure, flow, resistance and blood viscosity: flow = ml/min, p = hydrostatic fluid pressure, resistance force opposing blood flow, turbulence/laminar flow movement of blood, viscosity fluid resistance to flow. Flow is proportional to pressure gradients: across the ends of the blood vessel. Flow inversely proportional to resistance: effectively the diameter, since the walls are smooth. Diastolic and systolic: pressure to lift a column of mercury. Predictor of future problems: measured with a sphygmomanometer, auscultator by sound. Excessive pressure damages vessels, forces heart to work very hard. Elastic component of blood vessels in absence of pressure vessels can collapse. Lapla(cid:272)e"s law: wall tension = diameter * pressure.
