Neurotransmitters and its mechanism of action
Presented byR.Parthasarathy
INTRODUCTION:
What is neurotransmitterCriteriaGeneral characteristics featuresClassification biochemical physiologicalMechanism of action of individual chemical
ANATOMY OF NERVE:
Postsynaptic:
Muscle ContractionNeuron Action potentialGlands Secretion
DEFINITION:
Neurotransmitters are the chemical substances which are responsible for transmission of an impulse through a synapse.
Schematic diagram of synapse
CRETIA: 50 substance are there
Synthesized by pre-synaptic neurons with the help of synthesizing enzyme and stored in vesicles at axon terminal.
Stimulation of nerve cause release of transmitters.Travels between pre to post-synpatic membrane.Associated with an enzyme system(inactivation).Mimic the effects of nerve stimulation outside.Drugs which modifies nerve stimulation also
modifies transmitter action the similar way.
Neuromediators or neurohormones:
Neuromodulators:
Eg: VIP,somatostatin,ckk,substance P etc
Neuromodulators:
ACTION OF NEUROTRANSMITTERS general characteristics
Neurotransmitter travels pre post synapticReceptors associated with Ion channels and
enzyme(second messenger)Acts in millisecondsActivate both pre and post synaptic receptors.More transmitter interact both pre and post
synaptically (Sp Rec & sp effects)
CLASSIFICATION: BIOCHEMICALLY
PYSIOLOGICALLY
EXCITATORYEg:Acetylcholine
Aspartate
Dopamine
Histamine
Norepinephrine
Epinephrine
Glutamate
Serotonin
INHIBITORYGABA
Glycine
Excitatory neurotransmitters:
Inhibitory neurotransmitters:
Acetycholine:
SYNTHESIS:
• Vasodilation, • cardiac inhibition, • GI peristalsis; • control of thought, mood, sleep, muscles, bladder, sweat
glands
Catecholamines:
Dopamine:Control of movements(parkinsonism)Induction of vomitingInhibition of prolactin secretion Stimulation of GnRH Schizophrenia
SYNTESIS
Serotonin:
SYNTHESIS:
FUNCTIONS:Regulation Carbohydrate intake & Hypthalamic releasing hormonePain inhibitionHallucinations and 5HTDepression of mood
Histamine:
SYNTHESIS:
Amino acid:
SYNTHESIS:
OVERVIEW.
Neuropeptide transmitters:
General mechanism of action
Acetylcholine esterase
Thank you
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