Class 11 Biology Chapter 18 Neural Control and Coordination – Revision Notes

Neural Control and Coordination traces how a nerve impulse travels from receptor to effector, covering neuron structure, synaptic transmission, and the reflex arc along the way.

Last Updated: September 23, 2026

Neuron and Impulse

• Cell body, dendrites, axon.
• Resting potential (~−70mV); depolarization (Na⁺ in) → repolarization (K⁺ out).

Synapse

• Chemical synapse: neurotransmitter (e.g. acetylcholine) crosses synaptic cleft.

CNS and PNS

• CNS: brain (cerebrum, cerebellum, medulla) + spinal cord.
• PNS: somatic (voluntary) + autonomic (sympathetic/parasympathetic).

Reflex Arc

• Receptor → sensory neuron → spinal cord relay → motor neuron → effector; faster than voluntary response.

One-Line Summary

The nervous system controls and coordinates body functions through electrical nerve impulses (action potentials) and chemical synaptic transmission, with the CNS, PNS, and reflex arcs enabling both voluntary and rapid involuntary responses.

Frequently Asked Questions

What is the basic functional unit of the nervous system, and how does it transmit information?
The neuron is the basic functional unit of the nervous system, and it transmits information through electrical impulses that travel along its length and are passed to the next neuron through chemical signals at synapses.

What is a reflex action, and why is it faster than a voluntary response?
A reflex action is an automatic, involuntary response to a stimulus that bypasses the brain, being processed instead through the spinal cord via a reflex arc, making it much faster than a voluntary response.

Written by Satish

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