Question

please explain the topical structure of neuron in detail.

Answer 1

A typical neuron consists of a cell body (soma), dendrites, and an axon. The termneurite is used to describe either a dendrite or an axon, particularly in its undifferentiatedstage. Dendrites are thin structures that arise from the cell body, often extending for hundreds of micrometres and branching multiple times, giving rise to a complex "dendritic tree". An axon (also called a nerve fiber when myelinated) is a special cellular extension (process) that arises from the cell body at a site called the axon hillock and travels for a distance, as far as 1 meter in humans or even more in other species. Nerve fibers are often bundled into fascicles, and in the peripheral nervous system, bundles of fascicles make up nerves (like strands of wire make up cables). The cell body of a neuron frequently gives rise to multiple dendrites, but never to more than one axon, although the axon may branch hundreds of times before it terminates. At the majority of synapses, signals are sent from the axon of one neuron to a dendrite of another. There are, however, many exceptions to these rules: for example, neurons can lack dendrites, or have no axon, and synapses can connect an axon to another axon or a dendrite to another dendrite.

All neurons are electrically excitable, maintaining voltage gradients across theirmembranes by means of metabolically drivenion pumps, which combine with ion channelsembedded in the membrane to generate intracellular-versus-extracellular concentration differences of ions such assodium, potassium, chloride, and calcium. Changes in the cross-membrane voltage can alter the function of voltage-dependent ion channels. If the voltage changes by a large enough amount, an all-or-noneelectrochemical pulse called an action potential is generated, which travels rapidly along the cell's axon, and activates synaptic connections with other cells when it arrives.

In most cases, neurons are generated by special types of stem cells. Neurons in the adult brain generally do not undergo cell division. Astrocytes are star-shaped glial cellsthat have also been observed to turn into neurons by virtue of the stem cell characteristic pluripotency. Neurogenesis ceases during adulthood in most areas of the brain. However, there is strong evidence for generation of substantial numbers of new neurons in two brain areas, the hippocampus and olfactory bulb.
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Answer 2

Neuron is the longest cell in the human body. It consists of following parts:
•cell body or cyton- it is the broad rounded part of neuron with a central nucleus, abundant cytoplasm and various cell organelles.
•dendrites- the branched process of the body which receives and transmits stimulus.
•axon- the long fibre like cytoplasmic process that conducts impulses away from the cotton towards the nerve endings. It is the longest part of the neuron.
•nerve endings - the fine branched like terminations of neurons. This transfer the impulses to the dendrites of another neuron.