Neurotransmission & Neurotransmitter

Neurotransmission: Passage of an impulse across synaptic cleft or neuro effector junction due to release of neurotransmitter is called neurotransmission.

Neurotransmitter:It is a chemical substance which is released from nerve ending transmits impulse from nerve to nerve or nerve to effector organs.

Classification of neurotransmitter:

[A]According to type of action:

a)      Excitatory:

·         Ach.

·         Aspartate.

·         Glutamate.

·         PG.

·         Histamine.

b)      Inhibitory:

·         GABA.

·         Glycine.

·         Alanine.

·         Substance P.

c)       Mixed:

·         Adrenaline.

·         Dopamine.

·         NA.

[B]According to site of action:

a)      Peripheral neurotransmitter:Ach,histamin,adrenaline,noradrenaline.

b)      Central neuromtransmitter:Dopamin,GABA,glutamate,aspartate,serotonin.

Criteria of a neurotransmitter:

1)      NT must be released after some stimulus.

2)      The enzyme responsible for synthesis of NT must be present in the nerve ending.e.g Cholin acetyl transferase enzyme.

3)      The enzyme responsible for destruction of NT must be present in the nerve sending.e.g Cholinesterase enzyme.

4)      The effects of NT must be similar to the effects of exogenously administered NT.e.g the action of cholinomimetic drugs is simillar to the action of Ach.

5)      NT acts by binding with the specific receptor.e.g Cholinergic receptor.

6)      The actions of NT must be antagonised by the action of the antagonist of the NT.e.g Anti cholinergic drug.