BIPN 100 Notes 3a - BIPN 100 Cardiac Cycle Diastole Systole...

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BIPN 100 Cardiac Cycle Diastole + Systole, rest and contraction Diastole, ventricles are at rest after contracting, the pressure is lower, atria have higher pressure than the ventricle, which cause the AV valve to open, semilunar close, and ventricles fill Atria systole force small amount of remaining blood to ventricle Ventricular systole, increase pressure in ventricles, pushes AV valves close, the volume stays the same(isovolumic contraction), decrease pressure in arteries and push volume of blood- ejection period Ventricular diastole, pressure drops in arteries and ventricles, pressure forces arterial valves shut, and then AV valves open for blood to fill again Pressure-Volume Curves Pressure in Left Ventricle v. Volume of Left Ventricle The area represented by curve represents work done by left ventricle Diastolic Pressure, pressure that the ventricle has to overcome, the afterload Heart Sounds: Valve Closures Lub sounds is the AV valve closing, Dub is the arterial valve closing Systolic murmur is the narrowing of the AV valve Diastolic murmur is when the mitral valve doesn’t open properly End-Diastolic + End-Systolic Volumes End systolic volume or ESV, volume at the end of systole, amount of blood contained at diastole End diastolic volume or EDV, volume at the end of diastole, amount of blood contained at systole(also called pre-load) Stroke Volume + Ejection Fraction Stroke Volume = EDV-ESV
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Ejection Fraction=what fraction of ventricular blood ejected into arteries = SV/DV, usually between 50-75% Cardiac Output Cardiac Output = SV X Heart Rate, normal cardiac output for adult at rest is about 5 L/min At maximum exercise, one can increase CO to about 20-25 L/min Elite Athletes can go up to CO of 30-35 L/min Regulation of Cardiac Output Two systems, systemic and pulmonary blood flow Circulatory system controls output and input of ventricles, right heart = left heart Local: Frank-Starling Law of the Heart Frank Starling Law: If more blood ventricle, increase EDV, the ventricle will contract more forcefully and adapt, stroke volume will increase o Increases stroke volume in other ventricle also Length-tension relationship: stretching sarcomere filaments maximize contraction Point of diminishing return: increase in contraction hit maximum, heat failure results EDV is increased by increase in venous return, which is increased by muscle pumping of veins ~ have about 70 percent of the total blood volume Increasing respiration, increase volume and decrease pressure, increases stroke volume and cardiac output in the heart Autonomic + Naturiuretic Peptide Sympathetic stimulation causes increase of EDV, because of norephinephrine, beta 1 receptors increase calcium production in cardiac muscle Atrial Natriuretic Peptide (ANP) increases sodium secretion by the kidneys, decrease in amount of water decrease in blood volume, cause vasodilation Brain Naturietic Peptide (BNP) produced by brain, counteract extra contraction of heart
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