Question

Route of reflex arc is:
A. Receptors, effectors, grey mater and motor fibres
B. Receptors, sensory fibres, grey mater, motor fibres and effectors
C. Sensory fibres, grey mater, motor-fibres, receptors and effectors
D. Effectors, grey mater, motor, sensory fibres and receptors

Answer 1

Hint: Route of the reflex arc is nothing but how the signal travels in reflex action. There must be a receptor, effector, central nervous system, etc.

Complete Step by Step Answer:
You must have experienced a sudden withdrawal of any body part when in contact with a hot object which occurs involuntarily. The reflex arc is formed by the stimulus and effect of that stimulus. For example, the process from touching a hot object to retracting the hand is seen in the reflex arc.

To start a reaction, there must be a receptor which accepts the information (whether the object is hot) which is called an afferent neuron. It receives a signal from a sensory organ. It will take the signal from the receptor to the central nervous system (CNS). This conduction is done by sensory fibres. Grey matter is present in the central nervous system which is responsible for movement, memory and emotions.

Grey matter processes the signal there itself and signals the response. This conserves some time, as the time required for the signal to go to the brain and process takes some time as compared to the grey matter. Hence, the body does not get hurt badly.

Grey matter passes the signal to the muscle fibres to act on the signal. It either contracts or pulls to stop hurting the body. These signals are then transferred to the effector organs for the respective situation.
The correct order for the reflex arc will be afferent receptors, sensory fibres, the grey matter which is a part of the central nervous system, motor fibres to conduct the signal and effector organs.

Hence, The correct option is B.

Note: Reflex action is an involuntary action performed due to a stimulus. The simplest arrangement of the reflex arc is the receptor, interneuron and effector.