photo.jpg

## Neuron Structure - Has three basic parts: - **Cell body (soma)**: the control center of the neuron and contains the nucleus - **Dendrites**: which look like the bare branches of a tree, receive signals from other neurons and conduct information to the cell body - **Axon**: which carr...

## Neuron Structure - Has three basic parts: - **Cell body (soma)**: the control center of the neuron and contains the nucleus - **Dendrites**: which look like the bare branches of a tree, receive signals from other neurons and conduct information to the cell body - **Axon**: which carries nerve signals away from the cell body. Nerve cells have only one axon - **Myelin sheath**: axons of many neurons are encased. Consisting mostly of lipid, myelin acts to insulate the axon. In the peripheral nervous system Schwann cells form the myelin sheath. - **Nodes of Ranvier**: Gaps in the myelin sheath - **Synaptic Knob**: the end of the axon branches extensively with each axon terminal ending - **Myelin**: helps speed impulse conduction, nerve fibers stimulate skeletal muscles where speed is more important. - **Unmyelinated**: conducts nerve impulses more slowly, perform functions in which speed isn't essential. **Although myelination beings during the fourteenth week of fetal development, it is not complete until late adolescence** ## Life lessons: Multiple sclerosis MS is a disease in which the myelin sheaths surrounding the nerve of the CNS deteriorate and are replaced by hard scar tissue called Plaques.