Neural Control and Coordination NEET Notes 2027: Key Points and PDF

Neural Control and Coordination is Chapter 18 of NCERT Class 11 Biology and part of Unit 5, Human Physiology, of the NEET UG syllabus. These notes cover the human neural system, the structure and types of neurons, generation and conduction of the nerve impulse, transmission across synapses and the parts of the brain, with a free notes PDF.

Neural Control and Coordination NEET Notes

Section-wise key points from NCERT Chapter 18, comparison tables, high-yield facts and common mistakes for NEET 2027 revision.

Neural Control and Coordination at a Glance

The topic list follows the NEET UG 2026 syllabus released by the National Medical Commission (NMC) on 22 December 2025, which stays the reference until the 2027 syllabus is out. The full list is on the NEET syllabus page.

Reflex action and the sense organs (eye and ear) are no longer part of the rationalised NCERT chapter, and the NEET syllabus does not list them.

What is coordination and why do we need a neural system?

Coordination is the process through which two or more organs interact and complement the functions of one another; in our body the neural and endocrine systems do this together.

• Example from NCERT: during exercise, energy and oxygen demand rise, so the rate of respiration, heart beat and blood flow all increase; they return to normal after exercise stops.
• The neural system provides an organised network of point-to-point connections for quick coordination. The endocrine system provides chemical integration through hormones.
• The neural system of all animals is made of highly specialised cells called neurons, which detect, receive and transmit different kinds of stimuli.
• Hydra has a simple network of neurons; insects have a brain along with a number of ganglia and neural tissues; vertebrates have a more developed neural system.

How is the human neural system divided?

The human neural system has two parts: the central neural system (CNS), made of the brain and spinal cord, and the peripheral neural system (PNS), made of all the nerves associated with the CNS.

Neuron: the Structural and Functional Unit

A neuron is a microscopic structure with three major parts: the cell body, dendrites and the axon.

• Cell body: cytoplasm with typical cell organelles and granular bodies called Nissl’s granules.
• Dendrites: short, repeatedly branched fibres that also contain Nissl’s granules and carry impulses towards the cell body.
• Axon: a long fibre whose distal end is branched. Each branch ends in a bulb-like synaptic knob with synaptic vesicles containing neurotransmitters.
• Axons carry impulses away from the cell body to a synapse or to a neuro-muscular junction.

Myelinated and Non-myelinated Fibres

How is a nerve impulse generated and conducted?

A neuron is excitable because its membrane is polarised at rest; a stimulus reverses this polarity (depolarisation), and the wave of reversal travelling along the axon is the nerve impulse.

Resting State (polarised Membrane)

• Ion channels in the neural membrane are selectively permeable to different ions.
• At rest the axonal membrane is more permeable to K+ and nearly impermeable to Na+; it is also impermeable to the negatively charged proteins in the axoplasm.
• So the axoplasm has high K+ and negatively charged proteins and low Na+, while the fluid outside has low K+ and high Na+.
• The sodium-potassium pump maintains these gradients by active transport, moving 3 Na+ outwards for 2 K+ into the cell.
• Result: the outer surface is positive and the inner surface negative. This potential difference across the resting membrane is the resting potential.

Action Potential and Its Conduction

• A stimulus at site A makes the membrane freely permeable to Na+. Rapid Na+ influx reverses the polarity: outside becomes negative, inside positive. The membrane is now depolarised.
• The potential difference at site A is the action potential, which is the nerve impulse.
• Current flows on the inner surface from A to the next site B, and on the outer surface from B to A, completing the circuit. Polarity reverses at B and an action potential forms there.
• The sequence repeats along the axon, so the impulse is conducted.
• The rise in Na+ permeability is very short-lived and is quickly followed by a rise in K+ permeability. K+ diffuses out, restores the resting potential, and the fibre is ready for the next stimulus.

How is an impulse transmitted across a synapse?

A nerve impulse passes from one neuron to the next through a synapse, formed by the membranes of a pre-synaptic and a post-synaptic neuron that may or may not be separated by a synaptic cleft.

Steps at a Chemical Synapse

• The impulse (action potential) arrives at the axon terminal.
• Synaptic vesicles move to the membrane, fuse with it and release neurotransmitters into the synaptic cleft.
• Neurotransmitters bind to specific receptors on the post-synaptic membrane.
• Binding opens ion channels; entry of ions can generate a new potential in the post-synaptic neuron, which may be excitatory or inhibitory.

Central Neural System: the Brain and Its Protection

The brain is the central information processing organ of the body and acts as its command and control system.

• It controls voluntary movements, balance, vital involuntary organs (lungs, heart, kidneys), thermoregulation, hunger and thirst, circadian (24-hour) rhythms, several endocrine glands and human behaviour.
• It is also the site for processing vision, hearing, speech, memory, intelligence, emotions and thoughts.
• The skull protects the brain. Inside the skull, the cranial meninges cover it: outer dura mater, very thin middle arachnoid and inner pia mater (in contact with brain tissue).
• The brain has three major parts: forebrain, midbrain and hindbrain.

Forebrain, Midbrain and Hindbrain: Key Points

The forebrain has the cerebrum, thalamus and hypothalamus; the midbrain lies between the forebrain and the pons; the hindbrain has the pons, cerebellum and medulla.

Forebrain

• Cerebrum forms the major part of the human brain. A deep cleft divides it into left and right cerebral hemispheres, joined by a tract of nerve fibres called the corpus callosum.
• The cerebral cortex covers the hemispheres and is thrown into prominent folds. It is grey matter because neuron cell bodies are concentrated there.
• The cortex has motor areas, sensory areas and association areas; association areas handle complex functions such as intersensory associations, memory and communication.
• Myelinated fibre tracts form the inner part of the hemispheres and look opaque white, so they are called white matter.
• Thalamus: the cerebrum wraps around it; a major coordinating centre for sensory and motor signalling.
• Hypothalamus: lies at the base of the thalamus; has centres controlling body temperature and the urge for eating and drinking; its neurosecretory cells secrete hypothalamic hormones.
• Limbic system (limbic lobe): inner parts of the hemispheres with deep structures like the amygdala and hippocampus. With the hypothalamus it regulates sexual behaviour, emotional reactions (excitement, pleasure, rage, fear) and motivation.

Midbrain

• Located between the thalamus/hypothalamus of the forebrain and the pons of the hindbrain.
• The cerebral aqueduct, a canal, passes through it.
• Its dorsal portion has four round swellings (lobes) called corpora quadrigemina.
• The NCERT summary notes that the midbrain receives and integrates visual, tactile and auditory inputs.

Hindbrain

• Pons: fibre tracts that interconnect different regions of the brain.
• Cerebellum: very convoluted surface, giving extra space for many more neurons.
• Medulla (medulla oblongata): connected to the spinal cord; has centres controlling respiration, cardiovascular reflexes and gastric secretions.
• Brain stem = midbrain + pons + medulla oblongata. It connects the brain and spinal cord.

Most-asked Facts for NEET: Neural Control and Coordination

Revise these one-line facts from the NCERT chapter just before the exam.

• Neural system gives quick point-to-point coordination; the endocrine system gives chemical integration through hormones.
• Afferent fibres carry impulses to the CNS; efferent fibres carry them from the CNS.
• Autonomic neural system = sympathetic + parasympathetic.
• Nissl’s granules occur in the cell body and dendrites.
• Multipolar neurons: cerebral cortex; bipolar: retina; unipolar: embryonic stage.
• Myelin sheath is formed by Schwann cells; gaps between sheaths are nodes of Ranvier.
• Sodium-potassium pump: 3 Na+ out for 2 K+ in.
• At rest the axon is more permeable to K+; a stimulus makes it freely permeable to Na+.
• Resting membrane: outside positive, inside negative.
• Repolarisation comes from the rise in K+ permeability after the brief Na+ influx.
• Electrical synapses are faster than chemical synapses but rare in our body.
• Meninges from outside in: dura mater, arachnoid, pia mater.
• Corpus callosum joins the two cerebral hemispheres.
• Hypothalamus controls body temperature, eating and drinking and secretes hypothalamic hormones.
• Corpora quadrigemina lie on the dorsal midbrain; the cerebral aqueduct passes through the midbrain.
• Medulla controls respiration, cardiovascular reflexes and gastric secretions.
• Brain stem: midbrain, pons and medulla oblongata.

Common Mistakes to Avoid

Watch for these mix-ups when you answer questions on this chapter.

• Saying the inside of a resting axon is positive. At rest the outer surface is positive and the inner surface negative.
• Reversing the pump ratio. The sodium-potassium pump moves 3 Na+ out for every 2 K+ in.
• Saying Na+ leaving the axon restores the resting potential. It is restored by K+ diffusing out after the rise in K+ permeability.
• Saying non-myelinated fibres have no Schwann cells. They are enclosed by a Schwann cell that does not form a myelin sheath.
• Swapping neuron locations: bipolar neurons are in the retina, multipolar in the cerebral cortex.
• Calling chemical synapses faster. Transmission across an electrical synapse is always faster.
• Including the cerebellum in the brain stem. The brain stem is the midbrain, pons and medulla oblongata.
• Confusing the corpus callosum (joins the cerebral hemispheres) with the corpora quadrigemina (four lobes of the midbrain).
• Calling the cerebral cortex white matter. The cortex is grey matter (cell bodies); the inner myelinated tracts are white matter.
• Revising reflex arcs and the eye and ear from older notes. These were removed from the rationalised NCERT chapter and are not in the NEET syllabus.

Neural Control and Coordination Notes PDF and Related Pages

Download the AglaSem notes for Neural Control and Coordination (key notes and important questions with answers) free: View PDF

• All chapters: NEET Biology notes
• Full topic list: NEET syllabus
• Practice: NEET question papers
• Source text: NCERT Chapter 18 (NCERT, Class 11 Biology)

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