Skeletal Muscle Physiology
O B J E C T I V E S 1. To define these terms used in describing muscle physiology: multiple motor unit summation, maximal stimulus, treppe, wave summation, and tetanus. 2. To identify two ways that the mode of stimulation can affect muscle force production. 3. To plot a graph relating stimulus strength and twitch force to illustrate graded muscle response. 4. To explain how slow, smooth, sustained contraction is possible in a skeletal muscle. 5. To graphically understand the relationships between passive, active, and total forces. 6. To identify the conditions under which muscle contraction is isometric or isotonic. 7. To describe in terms of length and force the transitions between isometric and isotonic conditions during a single muscle twitch. 8. To describe the effects of resistance and starting length on the initial velocity of shortening. 9. To explain why muscle force remains constant during isotonic shortening. 10. To explain experimental results in terms of muscle structure.
keletal muscles are composed of hundreds to thousands of individual cells, each doing their share of work in the production of force. As their name suggests, skeletal muscles move the skeleton. Skeletal muscles are remarkable machines; while allowing us the manual dexterity to create magnificent works of art, they are also capable of generating the brute force needed to lift a 100-lb. sack of concrete. When a skeletal muscle from an experimental animal is electrically stimulated, it behaves in the same way as a stimulated muscle in the intact body, that is, in vivo. Hence, such an experiment gives us valuable insight into muscle behavior. This set of computer simulations demonstrates many important physiological concepts of skeletal muscle contraction. The program graphically provides all the equipment and materials necessary for you, the investigator, to set up experimental conditions and observe the