Neurons

Three categories of neurons

• Sensory (afferent)

• _______ (efferent)

• Interneurons (association)

Motor

Neurons (nerve cells)

• excitable cells

• Generate and transmit ____

Messages

Parts of the neuron

• ____

• Axon

• Cell body

Dendrites

Dendrites - short branching projections a- carry info _____ the cell body

Toward

Axon - Carries info _____ from/the the cell body

Away

Contains nucleus and other organelles

Cell body

Myelin sheath form the ______ cells

Schwann

Nodes of Ranvier are ___

Gaps between adjacent Schwann cells

Saltatory conduction -

Messages jump from one node of Ranvier to the next

Ion channel - all only ____ ___ to pass through- may be open always or regulated by a “gate”

Certain ions

The “Gate” is a…

Protein that changes shape - opens or closes a channel

Active transport is when…

Sodium and potassium ions cross the membrane

Resting potential is when

A neuron is not conducting (More sodium outside and potassium inside)

Action potential is when

A neuron is stimulated

Depolarization

Reversal of charge across the membrane (now more positive inside)

A “threshold” causes

all Voltage gated-sodium channels to open

Repolaration

Restoration of the charge difference across the membrane (potassium goes out and makes it more negative)

Refractory period is a brief period following an_____ (NA+ channels are closed)

Action potential

Synapse

Junction between neuron and another cell