Q.Explain the Reflex Pathway with the help of a neat labelled diagram.

A reflex action is a sudden, spontaneous, automatic, involuntary response to a stimulus, and its pathway is the reflex arc.

Step 1. Receptor. A stimulus (e.g. touching something hot) is detected by a sensory receptor in the skin.

Step 2. Afferent (sensory) neuron. The receptor generates a nerve impulse, carried by an afferent nerve fibre into the spinal cord via the dorsal root, whose cell body sits in the dorsal root ganglion.

Step 3. Processing in the grey matter. For a simple monosynaptic reflex (like the knee-jerk), the sensory neuron synapses directly onto a motor neuron. For a complex polysynaptic reflex, an association (inter-)neuron in the grey matter first receives and integrates the sensory signal before routing it on.

Step 4. Efferent (motor) neuron. The signal is passed to a motor neuron in the ventral horn, whose axon leaves via the ventral root as an efferent nerve fibre. …

Present the reflex arc as a fixed five-part chain (receptor, afferent neuron, spinal-cord processing, efferent neuron, effector), noti …

• Routing the reflex pathway through the brain -- a defining feature of a (spinal) reflex arc is that it does NOT need to reach the brain first, which is exactly why it is fast. …