Neurotransmitters

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Acetylcholine

1. In NMJ: stimulates skel. ms. contraction

2. In ANS: excitatory & inhibitory

- From all preganglionic autonomic n.

- From all postganglionic parasymp. n.

- From postgangl. symp. n. supplying sweat glds

Norepinephrine

1. In ANS: excitatory or inhibitory.

- Secreted from all postganglionic sympathetic neurons except those supplying sweat glands

- Secreted from adrenal medulla

2. In CNS: few fibers, highly branched  project to many areas

- Determine the state of alertness

Epinephrine

- Secreted from adrenal medulla

Dopamine

-It is only present in CNS

- Controls body movements

- Involved in sensory perception, mood & attention

Serotonin

- Fibers secreting serotonin innervate almost every structure in brain & spinal cord

- Decreased in abnormal behaviour (eg. depression)

GABA

- inhibitory

- Used mostly by interneurons → dampens action of neuronal circuits → prevents overexcitement of brain

Nitric Oxide

• smooth ms. relaxation

• GIT, penis, respiratory passages & cerebral blood vessels