Question

Observe the given figure and identify the labelled parts P, Q, R and S.

Hint:

Reflex arc pathway: Receptor → Sensory neuron → Spinal cord → Motor neuron → Effector.

Answer 1

Concept: The given diagram represents a reflex arc. A reflex arc is the pathway followed by nerve impulses during a reflex action. It involves receptors, sensory neurons, the spinal cord, motor neurons, and effectors. Identification of Labelled Parts:

• P – Receptor (in skin)
• Q – Sensory neuron
• R – Spinal cord (relay neuron/interneuron)
• S – Motor neuron

Explanation:

• The receptor (P) detects the stimulus (hot object).
• The sensory neuron (Q) carries the impulse to the spinal cord.
• The spinal cord (R) processes the information through a relay neuron.
• The motor neuron (S) carries the response to the muscles (effector).