Download PSE4U EXERCISE SCIENCE

PSE4U EXERCISE SCIENCE
Section 7 Cardiovascular System
Pathway of Conduction/Cardiac Cycle
1. Provide students with a handout of the cardiac cycle and ask students to outline the
diastole and systole cycles.
The pathway of conduction diagram provided is adapted from the O.A.C. Physical and
Health Education, Core Concept A: Human Performance. The Halton District School
Board.
a) Pathway of conduction:
Four Components of the cardiac conduction system:
i) Sinoatrial (SA) node
ii) Atrioventricular (AV) node – located in the right atrium along the lower part of the
iii) Atrioventricular (AV) bundle (Bundle of His)
iv) Purkinje fibres
 cardiac control centre located in the brain (medulla oblongata), the impulse for the
heart contraction travels down to the sinoatrial (SA) node (the “pacemaker”)
 a group of specialized nerve tissue located in the posterior wall of the right atrium
 the electrical impulse generated by the SA node spreads through both atria and
reaches the atrioventricular (AV) node, located in the right atrial wall near the centre
of the heart, causing the atria to contract
 the heart is in diastole (atria contracting and ventricles filling)
 the AV node conducts the impulse from the atria and travels down AV bundle to the
purkinje fibres
 within the ventricular septum, the AV bundle divides into right and left branches into
both ventricles
 these branches send the impulse to the apex of the heart and subdivide into terminal
branches called the Purkinje fibres
 the Purkinje fibres cause the ventricles to contract from the apex up
 the heart is in systole (ventricles contracting and emptying)
b) Cardiac Cycle: one complete heart beat
diastole = relaxation of the ventricles (the chambers fill with blood)
systole = contraction of the ventricles (the chambers contract and expel blood)
c) Stroke Volume (SV): volume of blood pumped by one ventricle during one beat
(ml/stroke)
d) Cardiac Output (Q): volume of blood pumped by one ventricle in one minute (l/min)
SV x HR = Q
e) Heart Rate (HR): number of times ventricles beat per minute
Information provided is adapted from the following resources:
Kapit, W. and L.M.Elson. The Anatomy Colouring book (Third Edition). Toronto:
Benjamin Cummings, 2001. ISBN 0-8053-5086-1
Wilmore, J.H. and D.L. Costill. Physiology of Sport and Exercise (Second Edition).
U.S.A.: Human Kinetics, 1999. ISBN 0-7360-0084-4