Explain the type of action involved in the contraction of pupil when the eyes are exposed to the bright light.

Explanation

Reflex action is contraction of pupil of the eyes when they are exposed to bright light.
(a) A reflex action is an involuntary and almost instantaneous response to a stimulus.
(b) The nerve pathway along which the impulses transmit to generate a reflex action is called reflex arc.
(c) The pathway has the following components:
(i) Stimulus-receptor perceives the stimulus
(ii) Sensory neurons—these neurons transmit the impulse to the spinal cord
(iii) Spinal cord—relay neurons connect the sensory neurons and the motor neurons in the spinal cord.
(iv) Motor neurons—these neurons send nerve impulses away from the central nervous system to the effector.