Download 20-03_pptlect

Anatomy & Physiology
SIXTH EDITION
Chapter 20, part 3
The Heart
PowerPoint® Lecture Slide Presentation prepared by
Dr. Kathleen A. Ireland, Biology Instructor, Seabury Hall, Maui, Hawaii
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Frederic H. Martini
Fundamentals of
Contractile Cells
• Resting membrane potential of approximately –
90mV
• Action potential
• Rapid depolarization
• A plateau phase unique to cardiac muscle
• Repolarization
• Refractory period follows the action potential
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Calcium Ion and Cardiac contraction
• Cardiac action potentials cause an increase in
Ca2+ around myofibrils
• Ca2+ enters the cell membranes during the
plateau phase
• Additional Ca2+ is released from reserves in the
sarcoplasmic reticulum
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 20.15 The Action Potential in Skeletal
and Cardiac Muscle
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 20.15
Figure 20.15 The Action Potential in Skeletal
and Cardiac Muscle
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 20.15
The cardiac cycle
• The period between the start of one heartbeat
and the beginning of the next
• During a cardiac cycle
• Each heart chamber goes through systole and
diastole
• Correct pressure relationships are dependent
on careful timing of contractions
PLAY
Animation: Intrinsic Conduction System
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 20.16 Phases of the Cardiac Cycle
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 20.16
Figure 20.16 Phases of the Cardiac Cycle
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 20.16
Pressure and volume changes: atrial systole
• rising atrial pressure pushes blood into the
ventricle
• atrial systole
• the end-diastolic volume (EDV) of blood is in the
ventricles
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Pressure and volume changes: ventricular systole
• Isovolumetric contraction of the ventricles:
ventricles are contracting but there is no blood
flow
• Ventricular pressure increases forcing blood
through the semilunar valves
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Pressure and volume changes: ventricular
diastole
• The period of isovolumetric relaxation when all
heart valves are closed
• Atrial pressure forces the AV valves open
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 20.17 Pressure and Volume Relationships
in the Cardiac Cycle
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 20.17
Heart sounds
• Auscultation – listening to heart sound via
stethoscope
• Four heart sounds
• S1 – “lubb” caused by the closing of the AV
valves
• S2 – “dupp” caused by the closing of the
semilunar valves
• S3 – a faint sound associated with blood
flowing into the ventricles
• S4 – another faint sound associated with atrial
contraction
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 20.18 Heart Sounds
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 20.18a, b
SECTION 20-4
Cardiodynamics
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Stroke Volume and Cardiac Output
• Cardiac output – the amount of blood pumped by
each ventricle in one minute
• Cardiac output equals heart rate times stroke
volume
CO
HR
Cardiac output
Heart rate
(ml/min)
=
(beats/min)
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
SV
X
Stroke
volume
(ml/beat)
Figure 20.19 A Simple Model of Stroke Volume
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 20.19a-d