MCAT Anatomy > Nervous System > Axons

Axons

Background

MCAT Nervous System - Motor Axon

The soma cell body contains the nucleus, ribosomes and the endoplasmic reticulum of the nervous system cells, which is impermeable to charged species. The ER of these cells are extremely well developed and are capable of producing a massive amount of proteins. The nervous system cells are just specialized eukaryotic cells.

The axon is a nerve fiber specifically designed to carry an electrical message and is insulated by a myelin sheath to prevent signal loss and increase signal conduction throughout the body. This ensures the charge is not lost to the surroundings and passes with the greatest speed to the muscle of interest.

The axon hillock is the enlargement at the beginning of the atom, which provides a cell body and axon connection. Likewise, the axon terminal (synaptic knob) forms the end of the nerve and usually contacts a synapse.

Dendrites receive information and transmit into the soma cell body. These cells are extremely branched in order to increase surface area.

Myelin constructed of fatty acids and is produced by oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system. Myelin provides insulating coating to help speed up the conduction of the nerve signal and also protect it from moving outside of the cell. This causes the action potential that is generated to jump between the nodes of Ranvier.

Nodes of Ranvier are small breaks in the sheath at regular intervals that are critical to proper signal conduction. The electrical action potential helps speed up conduction through the axon.

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