Neuron Structure and Synaptic Transmission — NEET Biology
✅ Asked in NEET 2024These fibres transmit impulses towards the cell body. The axon is a long fibre, the distal end of which is branched. Each branch terminates as a bulb-like structure called synaptic knobs which possess synaptic vesicles containing chemicals called neurotransmitters. The axons transmit nerve impulses away from the cell body to a synapse or to a neuro-muscular junction. Based on the number of axon and dendrites, the neurons are divided into three types, i.e. multipolar (with one axon and two or more dendrites), bipolar (with one axon and one dendrite) and unipolar (cell body with one axon only; found usually in the embryonic stage). There are two types of axons, namely, myelinated and non-myelinated. The myelinated nerve fibres are enveloped with Schwann cells, which form a myelin sheath around the axon. The gaps between two adjacent myelin sheaths are called nodes of Ranvier. Myelinated nerve fibres are found in spinal and cranial nerves. Unmyelinated nerve fibre is enclosed by a Schwann cell that does not form a myelin sheath around the axon, and is commonly found in autonomous and the somatic neural systems.
NTA tests your understanding of neuron anatomy, especially the role of synaptic knobs and neurotransmitters in impulse transmission, along with neuron classification (multipolar, bipolar, unipolar) and axon types (myelinated vs unmyelinated). Students commonly confuse the direction of impulse transmission—dendrites carry impulses TOWARD the cell body, while axons carry them AWAY. Another trap: mixing up myelin sheath formation—Schwann cells form myelin in myelinated fibers but don't in unmyelinated fibers. Remember: synaptic knobs release neurotransmitters at synapses, nodes of Ranvier are gaps in myelin sheaths, and myelinated fibers (spinal/cranial nerves) conduct faster than unmyelinated fibers (autonomous nervous system).
This paragraph was tested 2 times in NEET.
Match List-I with List-II List-I A. Schwann cells B. Synaptic knob C. Bipolar neurons D. Multipolar neurons List-II I. Neurotransmitter II. Cerebral cortex III. Myelin sheath IV. Retina [NEET 2024 Re]
[NEET Re-2022] Match the neuron types and locations:
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