6.1 Structure of Neurons

Axon

Extension from neuron cell body; propagates action potentials away from cell body

Axon Hillock

The part of a neuron where an axon leaves the cell body; site of action potential origination

Axon Terminal

End of axon; transmits information to other neurons/effector cells, and forms synaptic or neuroeffector junction with postjunctional cell

Cell Body (Soma)

In cells with long extensions, the part that contains the nucleus

Central Nervous System (CNS)

Brain and spinal cord

Dendrites

Highly branched extensions of neuron cell body; receive synaptic input from other neurons

Dendritic Spines

Small protrusions from dendrites that receive synapses from axons

Glial Cells

Nonneuronal cells in the central nervous system; help regulate extracellular environment of central nervous system

Initial Segment

First portion of axon plus the part of the cell body where axon arises

Myelin

Insulating material covering axons of many neurons; consists of layers of myelin-forming cell plasma membrane wrapped around axon

Neuron

Cell in nervous system specialized to initiate, integrate, and conduct electrical signals

Neurotransmitters

Chemical messengers used by neurons to communicate with each other or with effectors

Nodes of Ranvier

Spaces between adjacent myelin-forming cells along myelinated axon where axonal plasma membrane is exposed to extracellular fluid

Oligodendrocytes

Type of glial cells; responsible for myelin formation in the central nervous system

Peripheral Nervous System (PNS)

Neurons outside/extending from the central nervous system

Schwann Cells

Nonneural cells that form myelin sheath in the peripheral nervous system