This preview shows pages 1–3. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: ( TA NOTES IN RED ) Lecture 20: Cardiovascular System - Cardiac Physiology Reading: chapter 9, section: mechanical events, pgs 315-320 (pgs 320-325, if using 5 th edition) chapter 9, section: cardiac output and its control, pgs 320-326 (pgs 325-332, if using 5 th edition) Mechanical Events of the Cardiac Cycle - The cardiac cycle consists of alternate periods of contraction and emptying ( systole ) ( GREATEST PRESSURE ) and relaxation and filling ( diastole ) ( LEAST PRESSURE ) . These events occur in both the atria and the ventricles. A well-defined sequence of changes in pressure, volume, electrical activity and valve activity occur during each cycle (Figure 9-17,9-18) . The sequence is often described with respect to ventricular activity as a reference . Several key events of the cycle are defined below. end-diastolic volume - the volume of blood ( USUALLY IN ML ) in the chamber at the end of diastole. This is equivalent to the maximum amount of blood that the chamber will hold during the cycle. isovolumetric ventricular contraction ( ISOVOLUMETRIC = SAME VOLUME , NO BLOOD ENTERS OR LEAVES DURING THIS PERIDO ) - period of time during contraction when the chamber remains closed, and therefore no blood can enter or leave. Chamber pressure increases during this period. end-systolic volume - the amount of blood remaining in the chamber at the end of systole when ejection is complete. ( THIS IS THE LEAST AMOUNT OF BLOOD THAT WILL BE FOUND IN THE CHAMBER , IT A SMALL , RESIDUAL AMOUNT ) stroke volume - the amount of blood pumped out of the chamber with each contraction. Equal to the end-diastolic volume minus the end-systolic volume. ( KNOW THIS RELATIONSHIP ) isovolumetric ( CONSTANT VOLUME ) ventricular relaxation - period of time during relaxation when the chamber remains closed, and therefore no blood can enter or leave. Chamber pressure decreases during this period. Heart Sounds ( ARE ACTUALLY THE VALVES CLOSING , NOT THE CONTRACTION OF THE HEART PER SE ) first heart sound - low-pitched, soft and relatively long sound associated with the closure of the AV valves. Often referred to as a "lub". second heart sound - high-pitched, sharp and relatively short sound associated with the closing of the semilunar valves. Often referred to as a "dup" ( L AMINAR FLOW = SMOOTH & QUIET ( ALL THE PARTICLES ARE MOVING IN SAME DIRECTION ) TURBULENT FLOW = NOISY , PARTICLES MOVING IN VARIOUS DIRECTIONS ) murmurs - abnormal heart sounds, often associated with cardiac disease, that are due to the turbulent flow of blood through malfunctioning valves (Table 9-2) ....
View Full Document
This note was uploaded on 05/02/2008 for the course NPB 101 taught by Professor Fuller,charles/goldberg,jack during the Winter '08 term at UC Davis.
- Winter '08