81.Spastic paralysis occurs when a.descending excitatory pathways destroyed b.excitatory inputs to motor

Question : 81.Spastic paralysis occurs when a.descending excitatory pathways destroyed b.excitatory inputs to motor : 1417088


81.Spastic paralysis occurs when

a.descending excitatory pathways are destroyed

b.excitatory inputs to motor neurons are unopposed because of disruption of an inhibitory system in the brain stem

c.muscle spindles are destroyed

d.the cerebellum is damaged

e.the motor neurons are destroyed

82.During coactivation,

a.all muscle fibers in a skeletal muscle are activated simultaneously

b.the gamma motor-neuron and alpha motor-neuron systems to a skeletal muscle are activated simultaneously

c.all cross bridges within a single skeletal muscle are activated simultaneously

d.the primary (annulospiral) and secondary (flower-spray) endings within a muscle spindle are activated simultaneously

e.none of the above occur

83.Intrafusal muscle fibers

a.are supplied by alpha motor neurons

b.are found within muscle spindles

c.contain sensory nerve endings that are activated by stretch

d.have characteristics a and c

e.have characteristics b and c

84.The stretch receptors in the central portion of the muscle spindle can be activated by

a.passive stretch of the whole muscle, including stretch of the muscle spindle

b.contraction of the end portions of the muscle spindle

c.gamma motor neuron stimulation of the muscle spindle

d.all of the above

e.none of the above

85.Stretch reflexes are important for

a.maintaining balance and posture

b.providing afferent information to the primary motor cortex

c.determining which skeletal muscles will be used for a certain activity.

d.both a and b

e.both b and c

86.Calcium turns on cross bridges by physically repositioning the troponin-tropomyosin complex to uncover the actin cross-bridge binding sites in

a.skeletal muscle

b.cardiac muscle

c.smooth muscle

d.striated muscle

e.all of the above except c

87.Choose the false statement about smooth muscle.

a.It is under involuntary control.

b.It does not have troponin.

c.Its contraction is initiated neurogenically only.

d.It is found in walls of hollow tube-like organs.

e.It is innervated by the ANS.

88.Cardiac muscle tissue

a.has well developed sarcoplasmic reticulum

b.has fast myosin ATPase activity

c.contracts only when stimulated neurogenically

d.has gap junctions

e.stores calcium in its T tubules

89.The regulation of smooth muscle contraction is mediated by the phosphorylation of ____ in response to calcium binding to ____.

a.myosin; calmodulin

b.actin; calmodulin

c.troponin; calmodulin

d.myosin; troponin

e.actin; troponin

90.Select the correct statement regarding smooth muscle.

a.It composes the walls of the heart.

b.It is absent in the walls of hollow organs.

c.Its cells are multinucleated.

d.Its cells are spindle-shaped.

e.Its cells lack actin and myosin.


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Biology 1 Year Ago 32 Views
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