Human Anatomy

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  • Topic: Muscle, Biceps brachii muscle, Flexion
  • Pages : 2 (553 words )
  • Download(s) : 1741
  • Published : September 22, 2008
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Multiple Choice Chapter 6

1.A, C, D, E
4.B, D
5.A, B, C, D
6.B, C
7.B, D
8.A, B

8. Isotonic contraction (“same tone” or tension) - In isotonic contractions, myofilaments are successful in their sliding movements, the muscle shortens, and movement occurs. Contractions in which the muscles do not shorten are called isometric contractions (“same measurement” or length). In isometric contractions, the myosin mysofilaments are “skidding their wheels,” and the twnaion in the muscle keeps increasing.

9. Muscle tone is a state of continuous partial contractions. Muscle tone is the result of different motor units, which are scattered through the muscle, being stimulated by the nervous system in a systematic way. If the nerve supply to a muscle is n longer stimulated in this manner, and it loses tone and becomes paralyzed. Soon After, it becomes flaccid, or soft and flabby, and begins to atrophy.

10. One of these points, the origin, is attached to the immovable or less movable bone. The insertion is attached to the movable bone, and when the muscle contracts, the insertion moves toward the origin.

12. A prime mover is a muscle that has the major responsibility for causing a particular movement. Synergists help prime movers by producing the same movement or by reducing undesirable movements. Movements that oppose or reverse a movement are antagonists. When a prime mover is active, its antagonist is stretched and relaxed. Antagonists can be prime movers in their own right. For example, the biceps of the arm is antagonized by the triceps.

13. If I were alternately contracting and relaxing my masseter muscle I would be chewing. This muscle closes the jaw by elevating the mandible. Three facial muscles are: the orbicularis oculi which has fibers that run in circles around the eyes. It allows you to close your eyes, squint, blink, and wink. The orbicularis oris is the circular muscle of the lips. Because it closes the muscles the...
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