PHSI2005 Study Guide - Final Guide: Aortic Valve, Heart Valve, Isochoric Process
15 Jan 2019
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Phsi2005/2905 notes: the phases of the cardiac cycle. 80 mmhg (cid:120) (cid:120) dicrotic notch = during isovolumetric relaxation, the pressure in the aorta is higher than the pressure in the ventricles, so blood wants to flow out. However, semilunar valves shut, causing a small blip in the pressure (cid:120) peak pressure = systole = approx. 120 mmhg (cid:120) pressure continues to fall (throughout the arterioles, capillaries, venules, veins) Ventricular pressure wave (teal) (cid:120) ventricles initially fill with blood, so there is a slight increase in pressure (cid:120) when av valves shut during isovolumetric contraction, pressure increases (cid:120) It suggests that the stroke volume can change, depending on physiological demands (cid:120) note: cardiac output = volume of blood leaving the heart per minute. Heart sounds (cid:120) when valves shut, right before the isovolumetric contraction and relaxation. Electrocardiogram (cid:120) picks up the current that moves through the muscles of the heart. Also current that causes relaxation of atria (but is masked)
