Question

A stretch reflex begins with which branch of the nervous system. What is the integrating centre for the knee jerk? What is the approximate vibratory stimulus in Hertz required for a tonic vibration reflex? What division of the efferent nervous system controls contraction of gastrointestinal muscle? What sort of neurons arc involved in polysynaptic reflexes that are not involved in monosynaptic reflexes? The efferent output from the knee jerk targets what muscles and how do they respond? Would you expect the Edinger-Westphal nucleus to be associated with 'fight or flight' or 'rest and digest'? Why? The positive waveform recorded in an EMG is a representation of what? Where is the stimulus for the knee jerk reflex applied and what is it intended to achieve initially?

Answer 1

1. A. Central nervous system is related to the stretch reflex action.

B. Spinal cord is the integration centre for Knee jerk. It is monosynaptic reflex and need only two neuron.

C. 30–100 Hz is the tonic vibration reflex. At this vibration it activates receptors of the skin, tendons and, most importantly, muscle spindles.

D. The autonomic nervous system (ANS) is a division of the peripheral nervous systemthat influences the function of internal organs including Gastrointestinal muscle contraction.

E. Monosynaptic means a single chemical synapse. For ex in peripheral muscle reflexes like patellar reflex, achilles reflex, a short stimulation to the muscle spindle results in contraction of the agonist or effector muscle. While , in polysynaptic reflex pathways, one or more interneurons connect afferent (sensory) and efferent (motor) signals. Most of the simple reflexes are polysynaptic, allowing activation or inhibition of polysynaptic reflexes within the brain.