Essay on Bauer Chapter 9

939 Words Jan 6th, 2013 4 Pages
Chapter 9 & 10
Short Answer and Critical Thinking

CHAPTER 9

Short answer

15. Name and describe the four functional abilities of muscle that are the basis for muscle response.
Contractibility- is the ability to shorten forcibly when adequately stimulated. This ability sets muscle apart from other tissue types.
Extensibility- is the ability to extend or stretch. Muscle cells shorten when contracting, but they can stretch even beyond their resting length, when relaxed.
Elasticity- is the ability of a muscle cell to recoil and resume its resting length after stretching.
16. Distinguish between (a) direct and indirect muscle attachments and (b) tendon and an aponeurosis.
(a.) In direct or fleshy attachments, the epimysium
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When the nervous system stimulates muscle fibers, the myosin heads on the thick filaments latch onto myosin-binding sites on the actin in the thin filaments an the sliding begins. These cross bridge attachments form and break several times during a contraction, acting like tiny ratchets to generate tension and propel the think filaments toward the center of the sarcomere. As this event occurs simultaneously in the sarcomeres throughout the cell, the muscle cell shortens. As the thin filaments slide centrally the Z discs to which they attach are pulled toward the M line. Overall as a muscle cell shortens, the I bands shorten, the distance between successive Z discs shortens, and the H zones disappear and the contiguous A bands move closer together but their length does not change.
19. Explain how a slight (but smooth) contraction differs from a vigorous contraction of the same muscle. Use the concepts of multiple unit summation.
A motor unit consists of one motor neuron and all the muscle fibers it innervates or supplies. When a motor neuron fires all the muscle it innervates contract. The number of muscle fibers per motor unit may be as several hundred or as few as four. The more motor units that are recruited, the greater the muscle force. Muscles that exert fine control have small motor units. By contrast, large weight bearing muscles whose movements are less precise have large motor units. The muscle fibers in

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