Question

From superficial to interior, describe the composition of a nerve. Be as detailed as possible.

Answer 1

Nerve fibre
From superficial to interior
1 Epinerium layer

2 .Perinerium

3. Endoneurium .

Nerve is contact bundle of axons located outside of central nervous system.

Individual nerve fibers (single axons) are covered with varying amounts of myelin and then covered by endoneurium.

These individually wrapped nerve fibers are then grouped into bundles of fibers called fascicles, which are covered by perineurium.

Finally, groups of fascicles are bundled together to form the peripheral nerve (such as the median nerve), which is covered by epineurium. Perineurium forms blood neuron barrier.

Typical neuron is made up of
1.Perikaryon or soma or cell body: Contains many Nissl bodies and Golgi bodies.Cell body has nuckeus and is lined by cell membrane
Function - Organises and keep the cell functions .
Nucleus function is to control the neuron
Cell membrane protects the cell.

2. Dendrites: are known as receptor zone where it receives the signals fron other dendrites and graded electrogenesis occurs.

3. Axon hillock: The thickened area of cell body from which axon arises. They lack RER, free ribosomes, and Golgi apparatus.
Function - nerve impulse action potential begins here because highest concentration of Sodium channels / unit area is seen here .

4 Axon arises from axon hillock which has nodes of ranvier present over ita surface.Also Schwann cells present here helps in myelination .
Function - Transmits signals from one neruron to another
Schwann cell - myelination
Nodes of ranvier - allow diffuion of ions fast so inpulse travel from one node of ranvier to another becuase of myelination and conduction is faster called saltatory conduction .

5 .Axons terminate as Synaptic knobs .
Function - Vesicles contain acetycholine help in contraction .

Between 2 axons there is synapse which
Transmit the information from one neuron to another.