The reflex arc, which is made of two neurons is known as:
Correct answer: A. Monosynaptic reflex arc
- A. Monosynaptic reflex arc
- B. Disynaptic reflex arc
- C. Polysynaptic reflex arc
- D. Asynaptic reflex arc
Explanation
Monosynaptic reflex arc has only two neurons, i.e. sensory and motor which form one synapse. Depending upon the number of synapses, reflexes are categorised as monosynaptic, disynaptic and polysynaptic ones. The reflex arc with single synapse and therefore, only 2 neurons (afferent and efferent neurons) is called monosynaptic. For example, stretch reflexes. Disynaptic arcs have one interneuron located between afferent and efferent neurons of the reflex arc i.e., they have two synapses and three neurons which makes option B incorrect. For example, inverse stretch arc. Polysynaptic reflexes are characterised by the presence of more than one interneuron between afferent and efferent neurons of the reflex arc i.e, more than three neurons which makes option C incorrect. For example, cross flexor reflex, withdrawal reflex etc. Option D is incorrect as reflex arc has at least one synapse and two neurons.
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About Reflexes and the Reflex Arc
A reflex arc shows how a rapid, automatic response travels from a receptor through a sensory neuron, relay neuron and motor neuron to an effector. The topic covers synapses, the spinal cord's role, and the difference between an involuntary reflex action and a slower voluntary response.
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