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CHEMICAL TRANSMITTERS. The most widely distributed transmitters are acetylcholine (ACH) and noradrenalin . acetylcholine cholinergic nerve cholinergic receptors.
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CHEMICAL TRANSMITTERS The most widely distributed transmitters are acetylcholine (ACH) and noradrenalin. • acetylcholinecholinergic nerve cholinergicreceptors. • noradrenalinadrenergic nerveadrenergic receptors. • adrenergic receptors : there are ά and β receptors, ά receptors are divided into ά1 and ά 2 receptors. • Subtypes of cholinergic receptor are nicotinic and muscarinic receptors.
Acetylcholine Site of release of acetylcholine(the cholinergic nerve fibers): I- Central cholinergic fibers: a)All the preganglionicsympathetic. b) All the preganglionicparasympathetic. c) All the somatic motor fibers supplying the skeletal muscles.
II- Peripheral cholinergic fibers: a) All the parasympathetic postganglionic fibers. b) Sympathetic postganglionic secretary fibers to sweat glands. c) Sympathetic postganglionic vasodilator fibers to blood vessels of skeletal muscle.
Actions of acetylcholine: • "the nicotine-like actions"nicotinic receptors. • "the muscarine-like actions" muscarinic receptors.
Myasthenia Gravis * It is a disease of the neuromuscular junction characterized by weakness and easy fatigability of skeletal musclesautoimmunity. * Destruction of the cell membrane over the motor end plate decreasing the receptor areafor acetyl choline.
Catecholamines Is the chemical transmitter of most of the postganglionic sympathetic nerves. ADRENERGIC RECEPTORS: • There are 2 main types of adrenergic receptors; ά and β. In each type there are 2 subtypes. So, there are ά1, ά2, β1andβ2 adrenergic receptors. • Different adrenergic receptors produce different actions in target organs.