Neuron
Definition
A neuron is a specialized cell that transmits nerve impulses (electrical signals) in the nervous system. It consists of a cell body (soma), dendrites (receive signals), and an axon (transmits signals). Neurons communicate with each other at synapses using neurotransmitters.
Key Points for NEET
- 1Three parts: cell body, dendrites, and axon
- 2Resting potential: -70mV
- 3Action potential propagates along axon
- 4Synaptic transmission uses neurotransmitters
- 5Types: sensory, motor, and interneurons
Example
Motor neurons transmitting signals from brain to muscles for movement
Asked in NEET
Common Mistakes to Avoid
- ✗Confusing dendrites (receive signals) with axons (transmit signals away from cell body)
- ✗Thinking nerve impulse is flow of electrons — it is flow of ions (Na⁺ in, K⁺ out) across membrane
- ✗Forgetting that signal at synapse is chemical (neurotransmitters), not electrical
Quick Revision Notes
- ⚡Resting potential: -70mV (K⁺ leak channels); Action potential: Na⁺ rushes in → depolarization to +30mV
- ⚡All-or-none principle: neuron either fires fully or not at all — no partial action potential
- ⚡Synapse: presynaptic → neurotransmitter (ACh, dopamine) → synaptic cleft → postsynaptic receptor
- ⚡Myelin sheath (Schwann cells in PNS, oligodendrocytes in CNS) → saltatory conduction at nodes of Ranvier
Related Terms
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