Class Notes (806,977)
Canada (492,550)
Religion (238)
RLGB10 (7)
Lecture 4

Lecture 4 Notes 2014.pdf

10 Pages
Unlock Document

University of Toronto Scarborough
Michael Inzlicht

1Lecture 4 The Cardiac Cycle Heart Pressures and Cardiac Output Heart Rate Regulation1 The Cardiac Cycle See lecture 3 notes for the detailed description of the cardiac cycleThe cardiac cycle is simply the cycle of changes in volume and pressure as well as the opening and closing of the AV and semilunar valves that occur during a single contraction and relaxation of the heart It is easiest to conceptualize this cycle if we begin during the late period of relaxation or late diastole At this point the ventricles are filling with blood passively with blood flowing from the vena cava through the right atria and into the right ventricle Blood also flows from the lungs through the pulmonary veins into the left atria and then into the left ventricleIn the final phase of the diastolic part of the cardiac cycle the atria contract pumping a little more blood into the ventricles The heart then enters its systolic or contraction phases of which there are two parts the first phase the isovolumetric phase involves the heart contracting but given that all of the valves are closed no blood actually leaves the heart at this point In the second part of systole the pressure differentials between the ventricles and the aortapulmonary artery become such that the valves open the aortic valve on the left the pulmonary valve on the right and blood is then pumped throughout the systemic circulation on the left or the pulmonary circulation on the right We then have an isovolumetric relaxation phase when the muscle tension in the heart begins to dissipate whilst the volume stays the same due to the closing of the valves Finally we return to the initial stage mid to late diastolethe pressure differential between the atria and the ventricles becomes such that the AV valve opens and blood begins to flow back into the ventricles setting the scene for the cycle to begin again We looked before at the cardiac cycle using a diagram which displayed four lines of dataatrial pressure ventricular pressure aortic pressure pulmonary pressure on the right side and
More Less

Related notes for RLGB10

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.