Structure of a Typical Neuron

Myelin

-A mixture of proteins and phospholipids forming a whitish insulating sheath around many nerve fibers -Function: increasing the speed at which impulses are conducted.

Soma or Cell Body

-Contains nucleus, nucleolus and usual organelles surrounded by cytoplasm -Nissl Bodies (made up of rough endoplasmic reticulum (RER) are e.g. organelles -What is the function of RER: protein synthesis -Function of Nissl Bodies: Neurotransmitter production

Synaptic End Bulb

-Found at end of axon terminal & contain synaptic vesicles that are filled with neurotransmitters

Axon

-One axon per neuron -Transports information away from the cell body of a neuron

Projections (Nerve Fibers)

-Projections are attached to soma -Two types of projections: +Dendrites +Axons

Typical Neurons

-Their size and shape vary -Are made up of two parts: +Soma (Cell Body) +Projections (Nerve Fibers) -Cluster of cell bodies of neurons in CNS are called Nucleus and in PNS are called Ganglion (Ganglia)

Dendrites

-Usually short and multiple in number -Profuse branching -Unmyelinated: Lacking a myelin sheath -Transports information towards the cell body of a neuron

Axon Hillock

-Wide area (cone shape) -Atom is attached to the cell body of the neuron -Unmyelinated: lacks myelin sheath

Nodes of Ranvier

Gaps in the myelin sheath

Myelinated Nerve Fibers

Matter that surrounds a nerve fiber

Axon Collaterals

Side branches of the axon

Axon Terminal (Telodendira)

The endpoint of a neuron where neurotransmitters are stored

Schwann Cell

a cell in the peripheral nervous system that is wrapped around a myelinated axon, providing one segment of its myelin sheath

Unmyelinated Nerve Fiber

lacks myelin sheath; Schwann cells are not wound around the axons but simply form a groove or valley in which the axon sits; appear GRAY in color.