18
The Cardiovascular System:
The Heart
The Pulmonary and Systemic Circuits
(p. 659)
Heart Anatomy
(pp. 659–671)
Size, Location, and Orientation (p. 659)
Coverings of the Heart (pp. 660–661)
Layers of the Heart Wall (pp. 661–662)
Chambers and Associated Great Vessels
(p. 662)
Heart Valves (pp. 662–668)
Pathway of Blood Through the Heart
(p. 668)
Coronary Circulation (pp. 668–671)
Cardiac Muscle Fibers
(pp. 671–674)
Microscopic Anatomy (p. 671)
Mechanism and Events of Contraction
(pp. 671–673)
Energy Requirements (pp. 673–674)
Heart Physiology
(pp. 674–685)
Electrical Events (pp. 674–678)
Heart Sounds (pp. 678–679)
Mechanical Events: The Cardiac Cycle
(pp. 679–681)
Cardiac Output (pp. 681–685)
Developmental Aspects
of the Heart
(pp. 685–687)
Before Birth (pp. 685–686)
Heart Function Throughout Life
(pp. 686–687)
658
O
ur ceaselessly beating heart has intrigued people for centuries.
Te ancient Greeks believed the heart was the seat of intelligence. Others thought
it was the source of emotions. While these ideas have proved false, we do know
that emotions affect heart rate. When your heart pounds or skips a beat, you become
acutely aware of how much you depend on this dynamic organ for your very life.
Despite its vital importance, the heart does not work alone. Indeed, it is only part of the
cardiovascular system, which includes the miles of blood vessels that run through your
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