What is a neurotransmitter?Chemicals secreted by neurons

Stimulated action potential in adjacent neurons

Two types of responses:ExcitatoryInhibitory

Types of ResponsesExcitatory:

Opens sodium gatesStarts a nerve

impulseInhibitory

Makes neuron more negative on inside Raises Threshold

Requires more stimulus to start a nerve impulse

SummationEffect produced by the accumulation of

neurotransmitters from two or more neurons

EXAMPLESNeurotransmitter

Excitatory or Inhibitory

Effect

Acetylcholine Both excitatory and inhibitory

•Involved with somatic & parasympathetic nervous systems•Stimulates skeletal muscles•Inhibits cardiac muscles

Norepinephrine (noradrealine)

Excitatory •Involved with sympathetic nervous system

Neurotransmitter

Excitatory or Inhibitory

Effect

Glutamate Excitatory •Cerebral cortex (brain) excitatory transmissions•75% of all transmissions

GABA (Gamma aminobutyric acid)

Inhibitory •Cerebral cortex inhibitory transmissions

Dopamine Excitatory •Elevates mood•Controls skeletal muscles

Seratonin Inhibitory •Involved in alertness , sleepiness, mood, thermoregulation

DisordersAlzheimer’s Disease

Low acetylcholine

Parkinson’s DiseaseLow dopamine

Drugs….Which are good? Which are bad?

Prescription drugsMade to alter neurotransmitter release

Addictive drugsInterfere with neurotransmittersProduce feeling of pleasure

Release dopamine

Prescription DrugsValium

Increases GABAResult: alleviate anxiety

ProzacEnhances serotoninResult: antidepressant

Drug and Poison OverviewMuscle paralysis

E.g. Nerve gas, botulin toxin, some insecticides

Result: disrupts acetylcholine

StimulantsMimics norepinephrineResult: alertness,

excitement

DepressantsBlock

norepinephrine formation

Result: slows body activity, depression

HallucinogensInterferes with

serotonin

MethamphetamineEnters synaptic vessiclesCauses dopamine releaseBlocks dopamine from reentering synaptic

knobResult:

Increased pleasure

CocaineEnters synapseBlocks dopamine from reentering synaptic

knobResult:

Increased pleasure

NictoineBinds to receptor

on presynaptic neuron

Causes more dopamine to be released