Question

Define reflex arc. Draw a flow chart showing the sequence of events

Answer 1

Reflex action:the simplest form of response in the nervous system is reflex action.
Reflex arc:the pathway taken by nerve impulses in a reflex action is called reflex arc.
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Answer 2

Reflex action is  an unconscious, automatic and involuntary response of effectors, i.e., muscles and glands, to a stimulus, which is monitored through the spinal cord. The pathways of neurons involved in a reflex is known as reflex arc.

The mechanism of reflex action involve the following steps:

• Receptor organ like skin perceives the stimulus and activates a sensory nerve impulse.
• Sensory organ carries message in the form of sensory impulse to the spinal cord.
• The spinal cord acts as modulator. The neurons of spinal cord transmit the sensory nerve impulse to motor neuron.
• Motor nerve conducts these impulses to the effector like leg muscles which responds by pulling back the organ away from the harmful stimulus.