Learning Objectives

After completing this exercise, you should be able to

1. make use of a recording system and stimulator to record frog muscle responses to electrical stimulation;

2. determine the threshold level of electrical stimulation in frog muscle;

3. determine the intensity of stimulation needed for maximal muscle contraction;

4. record a single muscle twitch and identify its phases;

5. record the response of a muscle to increasing frequency of stimulation, and identify the patterns of tetanic contraction and fatigue.


• Wear disposable gloves when handling the frogs.

• Dispose of gloves and frogs as instructed.

• Wash your hands before leaving the laboratory.

To study the characteristics of certain physiological events such as muscle contractions, it often is necessary to use a recording device, such as a kymograph or a Physiograph. These devices are relatively simple to use, and they can provide accurate recordings of various physiological changes.

To observe the phenomenon of skeletal muscle contractions, muscles can be removed from anesthetized frogs. These muscles can be attached to record-

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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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