DOH100 Lecture Notes - Lecture 4: Heart Failure, T Wave, Pulmonary Edema
Document Summary
Explain how pressure and resistance determine the flow of a fluid. Pressure gradient = pressure difference between two points. Ventricular pressure must rise above this resistance for blood to flow into great vessels. Measured in mm hg with a manometer or sphygmomanometer. Resistance - vessel radius, length and blood viscosity. Describe the cardiac cycle and relate its phases to pressure changes, volume changes, heart sounds and ecg. The cardiac cycle is one complete contraction (systole) and relaxation (diastole) of all 4 chambers of the heart that typically lasts for 0. 8 sec, heart rate 75 bpm. Phase i ventricular filling: rapid ventricular filling. Filling completed by atrial contraction, ventricles now contain end-diastolic volume (edv) of about 130 ml of blood. P wave occurs just before atrial systole. Rising pressure closes av valves - lubb heart sound occurs. No ejection of blood, no change in volume. Rapid ejection of blood (left ventricular pressure peaks 120 mm hg)
