action potential

nerve

“tracts” found in the peripheral nervous system

(PNS)

tract

“nerves” that are found in the central nervous system

ganglion

“nucleus” (which is in the cns) found in the PNS

myelin sheath in CNS

one cell, many axons connect thru oligodendrocyte

myelin sheath in PNS

Each Schwann cell wraps its whole body around one segment of one axon

synapse

where neuron meets its target cell,

neurotransmitter

chemical messenger released by the presynaptic neuron to send signals to another cell across a synapse to the postsynaptic neuron

types of neurotransmitters

Acetylcholine (ACh)

Biogenic Amines

Amino Acids

Neuropeptides

potential generation

1. the cell is negative inside, positive outside

2. a stimulus connects to the channels

3. channel opens and Na+ fills in= positive inside

4. at -30 mV the Na+ channel closes and K+ channel opens

5. K+ flows out and inside is negative again

6. After one part of the membrane depolarizes, it triggers the next segment. which continues along the full axon

voltage gated ion channel

Open in response to changes in membrane potential.

Key for action potentials.

Na+

goes inside the postsynaptic neuron and makes it positive inside

K+

exits the postsynaptic neuron and makes it negative again

Ca2+

allows for stimuli to exit in the axon cell

ligand gated ion channels

Open when a specific molecule (ligand) binds.

Key for synaptic transmission

when ACh binds and lets Na+ in

mechanically gated ion channels

respond to pressure in sensory neurons

leak channel

passive channels that are always open

• K⁺ leak channels → more K⁺ leaves → inside stays negative at rest.

saltatory conduction

action potential travels fast, jumping, only happens in myelinated axons.

continuous conduction

action potential travels slow, step-by-step, only happens in unmyelinated axons