Anatomy & Physiology

Anatomy & Physiology Study Guide

13.2 Neurons Nerve cells specialized for intercellular communication are called neurons. Though neurons have many shapes, they have certain structures in common. Each neuron has a large cell body that is connected to a single axon and several short, branched dendrites.

13.3 Structure The Cell Body The cell body, or soma, contains a relatively well-built, round nucleus. The perikaryon is the cytoplasm surrounding the nucleus. The perikaryon contains neurofilaments and neurotubules within its cytoskeleton, which are similar to the filaments and microtubules of other types of cells. Internal collaboration for the branches of the soma is supported by bundles of neurofilaments called neurofibrils . They extend into the dendrites and axons. Most neurons lack centrioles and therefore cannot divide; thus, they cannot be inchanged if lost to injury or disease. Dendrites and Axons A number of “branches” known as dendrites extend out from the cell body. A neuron converts communication from other neurons through the dendrites. An axon is a long cytoplasmic process capable of propagating an electrical impulse known as an action potential. The base of the axon, or initial segment , of the axon in a multipolar neuron is connected to the cell body at a condensed region known as the axon hillock . The axon ends in a series of fine extensions, or telodendria . The telodendria of an axon end is at synaptic terminals.

©2018

Achieve Page 144

of 368