The Cardiac Cycle

MATERIALS NEEDED

textbook

For Procedure A—Heart Sounds:

stethoscope 70% alcohol absorbent cotton

For Procedure B—The Electrocardiogram:

electrocardiograph (or other instrument for recording an ECG) cot or table 70% alcohol absorbent cotton electrode cream (paste) plate electrodes and cables lead selector switch

Virtual Physiology Lab: 5, Electrocardiogram

A set of atrial contractions, followed by ventricular contractions, constitutes a cardiac cycle. Such a cycle is accompanied by blood pressure changes within the heart chambers, opening and closing of heart valves, and movement of blood in and out of the chambers. These events produce vibrations in the tissues and thus create the sounds associated with the heartbeat.

A number of electrical changes also occur in the myocardium as it contracts and relaxes. These changes can be detected by using metal electrodes and an instrument called an electrocardiograph. The recording produced by the instrument is an electrocardiogram, or ECG (EKG).

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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