Nervous System

Central Nervous System (CNS)

Brain and spinal cord

Peripheral Nervous System (PNS)

Nerves

Autonomic Nervous System (ANS)

Part of the PNS that controls parts of your body automatically

Neurons

Nerve Cells

Glia

Support Cells

Cell Body

Main part of neuron

Dendrites

Receive signals

Axon

Sends signals

Sensory (afferent) Nuerons

Send signals to the CNS

Motor (efferent) Neurons

Sends signals from the CNS to the rest of the body

Interneurons

Neurons that conduct signals from sensory to motor neurons

Myelin

White, fatty wrapping that covers the axon

Schwann Cells

Form myelin in PNS

Nodes of Ranvier

Spaces between Schwann cells

Neurilemma

Outer membrane of Schwann cells

Astrocytes

Star-shaped glia that attach neurons to blood vessels

Blood-Brain Barrier (BBB)

Separates blood from nervous tissue

Microglia

Digest microbes and dead neurons

Oligodendrocytes

Hold neurons together, includes Schwann cells

Nerves

Bundled nerve fibers in the PNS

Tracts

Bundle of axons in the CNS

White Matter

Tracts with myelinated axons

Gray Matter

Cell bodies and axons that are not myelinated

Endoneurium

Thin membrane covering each membrane

Fascicle

Bundle of nerve fibers

Perineurium

Thin membrane that surrounds each fascicle

Epineurium

Thick membrane that surrounds the whole nerve

Action Potential

Nerve impulse caused by a difference of electric charges

Neuron Pathway

Route of neurons that action potentials travel along

Reflex Arc

A basic type of neuron pathway

Receptors

Dendrites of sensory neuron

Ganglion

Bundle of sensory neurons located in the PNS

Synapse

Space between the axon of one neuron and the dendrites of another

Effector

An organ that turns an impulse into action

Reflex

The response to an impulse conducted over a reflex arc

Polarization

A resting neuron that has a slight positive charge on the outside of the membrane and a slight negative on the inside

Depolarization

Na+ channels open causing the inside of the membrane to become more positive

Repolarization

Return of the cell to resting state

Saltatory Conduction

Conduction of an action potential jumping from one node of Ranvier to the next in myelinated axons

Presynaptic Neuron

Neuron before the synapse

Postsynaptic Neuron

Neuron after the synapse

Synaptic Knob

Bulge at the end of the axon of the presynaptic neuron that contains neurotransmitters

Synaptic Cleft

The space between the neurons in a synapse

Neurotransmitters

Chemical messengers that cross the synaptic cleft and stimulate the postsynaptic neuron