Nervous SystemsPart 3

RA # 4.3

What is a synapse?

Gaps between neurons or between neurons

and effectors

Nerve Impulse is approaching the axon terminal by

Saltatory Conduction

Cell body

Schwann cell

Depolarized region(node of Ranvier)

Myelinsheath

Axon

Explain the steps of nerve impulse conversion

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+

The ability of the postsynaptic membrane to either turn on (EPSP) or turn off (IPSP) a nerve impulse.

COMPARE EPSP’s TO IPSP’s.

Explain the purpose of summation

Motorunit 1

Motorunit 2

Nerve

Synaptic terminals

Motor neuroncell body

Spinal cord

Motor neuronaxon

Muscle

Tendon

Muscle fibers

To reach threshold more quickly

What is the most common neurotransmitter in the human body?Acetylcholine

What is the “sleep” neurotransmitter?Serotonin

What neurotransmitter relays pain?Substance P

Which gas is AKA “laughing gas?”Nitric oxide

What do GABA’s do?Inhibit transmission

Which neurotransmitters create the “fight or flight” response?Epinephrine and norepinephrine

Which neurotransmitter is the “happy” neurotransmitter?Dopamine

What affect does carbon monoxide have on nerve transmission?Inhibits

What do endorphins do?Block Substance P