AP Biology

Nervous SystemsPart 3

Synapse and Neurotransmitter

Nerve Impulse is approaching the axon terminal by Saltatory Conduction

Cell body

Schwann cell

Depolarized region(node of Ranvier)

Myelinsheath

Axon

Synapse at the axon terminal

Postsynaptic cellPresynaptic cell

Synaptic vesiclescontainingneurotransmitter

Presynaptic membrane

Voltage-gatedCa2+ channel

Ca2+Postsynaptic membrane

Postsynaptic membrane

Neuro-transmitter

Ligand-gatedion channel

Na+

K+

Ligand-gatedion channels

Synaptic cleft

Post synaptic membrane

Resting potential

Threshold

Mem

bran

e po

tent

ial

(mV)

Actionpotential

Time–100

–50

+50

0

Potassiumchannel

Extracellular fluid

Plasma membrane

Na+

Resting state

Inactivationgate

Activationgates

Sodiumchannel K+

Cytosol

Na+

Depolarization

K+

Na+

Na+

Rising phase of the action potential

K+

Na+

Na+

Falling phase of the action potential

K+

Na+

Na+

Undershoot

K+

Na+

Synapse with effector cell Motor

unit 1Motorunit 2

Nerve

Synaptic terminals

Motor neuroncell body

Spinal cord

Motor neuronaxon

Muscle

Tendon

Muscle fibers