Muscle Physiology Question And Answers

Muscle Physiology

Regulation of muscle tone.
Answer:

Muscle tone:

• Muscle tone Definition:
  • The muscle fibers always maintain a state of slight contraction with certain degree of vigor and tension.
  • This property of muscle is called tone.
• Muscle tone Regulation;
  1. In skeletal muscle.
• Regulation of muscle tone in skeletal muscle is neurogenic.
• It is due to continuous discharge of impulses from gamma motor neurons in anterior gray horn of spinal cord.
• The gamma motor neurons innervate the intrafusal fibers present in the musle spindle.
• Muscle spindle is the proprioreceptor situated in the muscle.
• The impulses from the gamma motor neuron causes contraction of end portions of intrafusal fibers.
• So, the central portion of the intrafusal fibers is stretched and activated.
• It leads to discharge of impulses from the primary sensory nerve endings.
• These impulses stimulates the alpha motor neurons of the spinal cord.
• Now, these neurons send impulses to extrafusal fibers.
• This causes contraction of the muscle fibers.
• The gamma motor neurons, muscle spindle and muscle tone are all controlled by basal ganglia.

1. In cardiac muscle.

• Regulation of muscle tone in cardiac muscle is myogenic.
• The muscles themselves control the tone.

1. The smooth muscle.

• In smooth muscle, tone is myogenic.
• It depends upon calcium level and number of cross bridges.