Question

a) What would be the effect on the spinal stretch reflex of a specific muscle if the gamma efferents to that muscle were stimulated to fire at a higher rate than they had been initially? Briefly explain.

b) I ask you to generate force continuously with a muscle innervated by two motor units, a small one and a large one. I ask you to increase force gradually (starting from generating ZERO force), then maintain exerting a lot of force, then gradually relax until you are again generating ZERO force. On one graph, plot the firing rate versus time for both of these motor units. Do not plot individual action potentials!

Answer 1

a) The reflex function to maintain the muscles at constant length.Gamma neurone are constitute the motor neurone.Which enhances the muscle function.Gamma neuron innervate the muscle spindle at each end. they allow contraction of intrafusal fibres and increase their sencitivity to stretch.And the gamma neuron acts as a important muscle stretch reflex mechanism in conjuction with alpha neuron.

When the effect of an increased activity of gamma neuron then increase the activity of muscle length and leads to the increase in the spindle afferent activity level.

Strech reflex is an involutary action that streching the skeltal muscle.Incresing the activity of gamma neuron and the indirect increases of musle tone by increasing the sensory afferent and then the alpha motor neuron efferent.