2010-PSL-200-201--Cardio-03of07

2010-PSL-200-201--Cardio-03of07 - 1 Cardiovascular...

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Unformatted text preview: 1 Cardiovascular Physiology 3/7 Department of Physiology Nohjin Nohjin Kee Kee , Ph.D. , Ph.D. Email: Email: [email protected] [email protected] Office Hours TBA Office Hours TBA 2 The Cardiac Cycle he Cardiac Cycle The cardiac cycle includes all the events associated with the flow of blood through the heart during a single complete heartbeat The Pumping Cycle: includes the various phases in the pumping action of the heart Periods of Valve Opening and Closure Changes in Pressures (Atrial, Ventricular and Aortic - which reflect contraction and relaxation of the heart muscle) Changes in Ventricular Volume: which reflect the amount of blood entering and leaving the ventricle during each heartbeat Heart Sounds (two) 3 5. Heart Sounds 1. The Pumping Cycle 2. Valve Opening and Closure 3. Changes in Pressure 4. Changes in Ventricular Volume The Cardiac Cycle he Cardiac Cycle 4 5. Heart Sounds 1. The Pumping Cycle 2. Valve Opening and Closure 3. Changes in Pressure 4. Changes in Ventricular Volume The Cardiac Cycle he Cardiac Cycle 5 The Pumping Cycle • Because the cardiac cycle involves the events of one heartbeat, a complete cycle involves both ventricular contraction and ventricular relaxation • As a result, the cycle can be divided into two major stages: SYSTOLE, the period of ventricular CONTRACTION and DIASTOLE – ventricular RELAXATION We begin our examination of the cardiac cycle in the middle of diastole, a time at which the atria and ventricles are completely relaxed ardiac Cycle –umping Cycle 6 • Because the cardiac cycle involves the events of one heartbeat, a complete cycle involves both ventricular contraction and ventricular relaxation • As a result, the cycle can be divided into two major stages: SYSTOLE, the period of ventricular CONTRACTION and DIASTOLE – ventricular RELAXATION We begin our examination of the cardiac cycle in the middle of diastole, a time at which the atria and ventricles are completely relaxed The Pumping Cycle ardiac Cycle –umping Cycle 7 • Blood returning to the heart via the systemic and pulmonary veins enters the relaxed atria and passes through the AV valves and into the ventricles under its own pressure, i.e., the pressure in the veins is sufficiently high to drive the flow of blood into the heart (called venous return) • As the ventricles fill, the pulmonary and aortic (semilunar) valves are closed because ventricular pressure is lower than that in the aorta and pulmonary arteries Late in diastole (at the end of phase 1), the atria contract, driving more blood into the ventricles. Shortly thereafter, the atria relax and systole begins The Pumping Cycle Phase 1 ardiac Cycle –umping Cycle hase 1 8 • Blood returning to the heart via the systemic and pulmonary veins enters the relaxed atria and passes through the AV valves and into the ventricles under its own pressure, i.e., the pressure in the veins is sufficiently high to drive the flow of blood into the heart (called venous return)...
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This note was uploaded on 03/17/2011 for the course PSL 200 taught by Professor Averback during the Fall '11 term at University of Toronto.

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2010-PSL-200-201--Cardio-03of07 - 1 Cardiovascular...

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