Chapter Overview & Weightage
Neural Control and Coordination covers neuron structure, nerve impulse transmission, synaptic transmission, the central and peripheral nervous systems, reflex arcs, and sense organs (eye and ear). This is one of the more conceptual chapters in human physiology.
This chapter carries 4-5% weightage in NEET with 3-4 questions. Neuron physiology (resting potential, action potential), brain parts and functions, and eye/ear anatomy are the most tested areas.
Key Concepts You Must Know
Tier 1 (Core)
- Neuron structure: cell body (soma), dendrites, axon, myelin sheath (Schwann cells), nodes of Ranvier, synaptic knob
- Resting membrane potential: ~ mV (inside negative), maintained by Na/K pump
- Action potential: depolarisation (Na influx) → repolarisation (K efflux) → hyperpolarisation → restoration
- Synapse: synaptic cleft, neurotransmitter (ACh, etc.) release, binding to post-synaptic receptors
- Reflex arc: receptor → afferent nerve → CNS (integration) → efferent nerve → effector
Tier 2 (Frequently tested)
- Brain parts: cerebrum (thinking), cerebellum (balance/coordination), medulla oblongata (vital functions), hypothalamus (homeostasis, emotions), thalamus (relay centre)
- Cranial nerves: 12 pairs; spinal nerves: 31 pairs
- Eye: cornea → aqueous humor → lens → vitreous humor → retina (rods and cones)
- Ear: outer ear (pinna, ear canal) → middle ear (3 ossicles) → inner ear (cochlea for hearing, semicircular canals for balance)
Tier 3 (Occasionally tested)
- Saltatory conduction in myelinated neurons (faster)
- PNS divisions: somatic (voluntary) and autonomic (sympathetic + parasympathetic)
- Eye defects: myopia, hypermetropia, astigmatism, cataract, glaucoma
- Organ of Corti in cochlea (hearing receptor)
Important Formulas
| Phase | Ion Movement | Membrane Potential |
|---|---|---|
| Resting | Na/K pump active (3 Na out, 2 K in) | mV |
| Depolarisation | Na channels open, Na rushes IN | → mV |
| Repolarisation | K channels open, K rushes OUT | → mV |
| Hyperpolarisation | Excess K efflux | Below mV briefly |
| Restoration | Na/K pump restores ion balance | Back to mV |
| Brain Part | Key Functions |
|---|---|
| Cerebrum | Higher mental functions, sensory/motor areas, memory, speech |
| Cerebellum | Balance, posture, coordination of voluntary movements |
| Medulla oblongata | Breathing, heart rate, vomiting, swallowing (vital centres) |
| Hypothalamus | Body temperature, hunger, thirst, emotions, endocrine regulation |
| Thalamus | Relay station for sensory signals to cerebral cortex |
| Pons | Sleep-wake cycle, relay between cerebrum and cerebellum |
| Midbrain | Visual and auditory reflexes |
For NEET, link each brain part to ONE key function: cerebellum = balance, medulla = vital functions, hypothalamus = thermoregulation + hunger. When in doubt between thalamus and hypothalamus, remember: thalamus = relay, hypothalamus = homeostasis.
Solved Previous Year Questions
PYQ 1 — NEET 2024
Problem: During an action potential, depolarisation is caused by:
(A) K efflux (B) Na influx (C) Cl influx (D) Ca influx
Solution:
Depolarisation occurs when voltage-gated Na channels open, allowing Na to rush into the cell. This makes the inside of the cell more positive, changing the membrane potential from mV to about mV.
K efflux causes repolarisation (the next phase). Ca influx is important in muscle contraction and synaptic transmission but not in neuronal depolarisation.
Answer: (B) Na influx
PYQ 2 — NEET 2023
Problem: Which part of the brain controls body temperature?
(A) Cerebrum (B) Cerebellum (C) Hypothalamus (D) Medulla oblongata
Solution:
The hypothalamus is the thermoregulatory centre of the body. It monitors blood temperature and triggers responses (sweating, shivering, vasodilation/vasoconstriction) to maintain body temperature around 37 degrees C.
Answer: (C) Hypothalamus
PYQ 3 — NEET 2022
Problem: The
three ossicles of the middle ear are:
(A) Malleus, incus, stapes (B) Malleus, incus, cochlea (C) Pinna, malleus, incus (D) Stapes, cochlea, organ of Corti
Solution:
The three ear ossicles are malleus (hammer), incus (anvil), and stapes (stirrup). They form a chain from the tympanic membrane to the oval window, amplifying sound vibrations about 20 times. The stapes is the smallest bone in the human body.
Answer: (A) Malleus, incus, stapes
Difficulty Distribution
| Difficulty | % of Questions | What to Expect |
|---|---|---|
| Easy | 40% | Brain part functions, ossicle names, neuron parts |
| Medium | 45% | Action potential phases, reflex arc components, eye structure |
| Hard | 15% | Saltatory conduction details, neurotransmitter mechanisms |
Expert Strategy
Days 1-2: Neuron physiology — understand resting potential, action potential, and synaptic transmission as a connected story, not isolated facts. The ion movements tell a logical narrative.
Days 3-4: Brain anatomy and functions. Use NCERT diagrams to learn the parts. For each part, memorise ONE flagship function. Then learn the reflex arc as a complete pathway.
Day 5: Sense organs — eye and ear anatomy. Focus on the pathway of light through the eye and sound through the ear. Photoreceptors (rods for dim light/black-and-white, cones for bright light/colour) are frequently tested.
The eye section often appears as a diagram question. Know the parts in order: cornea → aqueous humour → pupil → lens → vitreous humour → retina. Also know that the image forms on the retina (inverted) and the fovea has the highest concentration of cones.
Common Traps
Trap 1 — Na enters during depolarisation, K exits during repolarisation. Students swap these. Remember: Depolarisation = Na Deluge (flooding in). Repolarisation = K Retreat (flowing out).
Trap 2 — Cerebellum controls coordination, not higher thinking. Damage to the cerebellum causes ataxia (loss of coordination), not loss of consciousness or memory. Cerebrum handles higher functions.
Trap 3 — Myelinated neurons conduct FASTER, not slower. Myelin acts as insulation, forcing the impulse to jump between nodes of Ranvier (saltatory conduction). This is faster than continuous conduction in unmyelinated fibres.
Trap 4 — Rods are for dim light, cones are for colour. Rods contain rhodopsin and work in low light (scotopic vision). Cones contain iodopsin and detect colour in bright light (photopic vision). Night blindness = rod dysfunction (Vitamin A deficiency).