Question

A person unconsciously withdraws his hand suddenly with a jerk, after touching a hot plate
(i) Draw a schematic diagram of the nervous pathway involved in this response.

(ii) What is such a response called?

(iii) How is this kind of response different from the one in which one begins to salivate at the sight of tasty food?

Answer 1

(ii) When a person withdraws his hand suddenly with a jerk after touching a hot plate this reflex is called a withdrawal reflex. This reflex is a spinal reflex intended to protect the body from damage. It is a polysynaptic reflex that stimulates the sensory, association and motor neurons, The heat stimulates the temperature and the danger receptors in the skin that triggers a sensory impulse that travels to the central nervous system and causes the withdrawal of the hand. It is an example of non-conditioned reflex that is already present by birth.

(iii) Salivating at the sight of tasty food is an example of conditioned reflexes. These are acquired during the lifetime of a person.