Question

When we touch a hot plate unknowingly, then this heat is sensed by a receptor P present in our fingers. The receptor triggers an impulse in neuron Q which transmits the message to an organ R which is a part of the central nervous system. Here the impulse is passed on to a neuron S which in turn passes it to a yet another neuron T. The neuron T passes the impulse to a tissue U in our arm. The tissue U then contracts and pulls our hand away from the hot plate.

(a) What is the name of (i) receptor P (ii) neuron Q, and (iii) organ R ?

(b) What is (i) neuron S, and (ii) neuron T ?

(c) Name the tissue U.

(d) What name is given to the phenomenon in which hand is pulled away quickly from the hot plate ?

(e) Name the effector in this whole process.

Answer 1

(a)

(i)P is a thermo receptor.

The five organs which contain receptors are

Eyes

Ears

Nose

Eyes

Tongue

Skin

(ii) Q represents sensory nerves. Sensory nerves carry impulses from the sensory organs to the CNS.

(iii) R is the Spinal cord.

(b) (i) Relay Neuron

(ii) Motor neuron

(c) Tissue U is the Muscle

(d)The phenomenon in which hand is pulled away quickly from the hot plate is called Reflex action.

(e) The effector in this whole process is the muscle of the arm.