Neurons and Neural Firing

Neuron

A nerve cell that communicates information in the nervous system.

Soma (cell body)

Contains the nucleus and DNA.

Dendrites

Receive signals from other neurons.

Axon

Carries a neural signal from the cell body toward the terminals.

Myelin sheath

Insulates and protects the axon.

Axon terminals (terminal buttons)

Send chemical messages to the next neuron.

Schwann cells

Produce myelin for the myelin sheath.

Nodes of Ranvier

Gaps between Schwann cells along the myelin sheath.

Glial cells (glia)

Support cells that provide neurons with protection and nourishment.

Resting potential

The neuron's slightly negative charge when not firing; ions are polarized.

Threshold

The minimum stimulation needed to trigger a neural impulse.

Action potential

Neural impulse when a neuron fires and ions exchange, causing depolarization.

All-or-nothing law

A neuron fires or does not fire once threshold is reached.

Depolarization

The change in electrical charge as ions exchange during a neural impulse.

Repolarization

The return of ions toward their original arrangement after firing.

Refractory period

The brief pause after a neuron fires while it resets before firing again.

Synapse (synaptic gap)

The small space between neurons.

Neurotransmitters

Chemical messengers released by axon terminals into the synapse.

How does a signal cross between neurons?

Electrical signal reaches terminals; neurotransmitters cross the synapse and bind to the next neuron.

Reuptake

The reabsorption of neurotransmitters by the sending neuron's axon terminals.

Communication within a neuron

Primarily electrical.

Communication between neurons

Chemical, using neurotransmitters.