45. Hours after a \"normal\" (non-stressful) death, the pH of the skeletal muscl

Question

45. Hours after a "normal" (non-stressful) death, the pH of the skeletal muscle will be:

A.       7.5                C.       3.5

B.       5.5                D.       8.5

46. The motor unit is defined as:

A.       many myofibrils within the sarcoplasm

B.        the functional myofilaments within a muscle fiber

C.       many motor endplates within a single neuromuscular function

D.       a motor neuron and the muscle fibers innervated by it

47. During contraction of a skeletal muscle cell:

a.        calcium ions are released from the transverse tubules to initiate contraction.

b.       calcium ions bind to the regulatory protein tropomyosin, which is associated with the thin filaments.

c.        neither the thin myofilaments nor the thick myofilaments change in length.

d.       all of the above

Explanation / Answer

45 ans C. 3.5

after death skeletal muscle becomes more acidic so ph values decreases

46.ans D. a motor neuron and muscle fibers inerveted by it

A motor unit is made up of a motor neuron and the skeletal muscle fibers innervated by that motor neuron's axonal terminals. Groups of motor units often work together to coordinate the contractions of a single muscle; all of the motor units within a muscle are considered a motor pool.

47.ans B.calcium ions bind to the regulatry protein tropomyosin, which is associated with the thin fillaments

In turn this triggers the sarcoplasmic reticulum to release calcium ions into the muscle interior where they bind to troponin, thus causing tropomyosin to shift from the face of the act in filament to which myosin heads need to bind to produce contraction.

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