Short Repeatedly Branched Fibres: Axon

An axon is a long, slender projection of a neuron that conducts electrical impulses away from the cell body, towards other neurons or target cells. It is the primary transmission line of the nervous system, responsible for transmitting and propagating action potentials.

Structure of an Axon:
- Axon Hillock: The axon hillock is the cone-shaped region of the neuron where the axon originates from the cell body. It is the site where action potentials are generated.
- Axon Proper: The axon proper is the elongated part of the axon that extends away from the cell body. It is covered by a lipid-rich insulating layer called the myelin sheath, which is produced by specialized supporting cells called Schwann cells in the peripheral nervous system, and oligodendrocytes in the central nervous system.
- Axon Terminal: At the distal end of the axon, there are fine branches called axon terminals or terminal boutons. These branches form synapses with other neurons or target cells, allowing for the transmission of signals.

Function of an Axon:
- Signal Transmission: The main function of an axon is to transmit electrical signals, known as action potentials, from the cell body to other neurons or target cells. These signals travel along the axon, facilitated by the myelin sheath and nodes of Ranvier, which allow for saltatory conduction. This rapid transmission of signals enables efficient communication within the nervous system.
- Synaptic Transmission: At the axon terminals, the electrical signals are converted into chemical signals. When an action potential reaches the axon terminal, it triggers the release of neurotransmitters into the synaptic cleft, which then bind to receptors on the target cell, transmitting the signal from one neuron to another or to an effector cell (such as a muscle cell or gland).

Conclusion:
In summary, the short repeatedly branched fibers in neurons are called axons. Axons play a vital role in the transmission of electrical signals throughout the nervous system, allowing for communication between neurons and the activation of target cells.