The conduction of most of the cholinergic nerves in the human body (including the preganglionic fibers of the motor sympathetic and parasympathetic nerves, the postganglionic fibers of the parasympathetic nerves and some sympathetic nerves) relies on the release of acetylcholine at the junction between its terminals and cells to innervate the effector organs. Acetylcholine is also involved in the transmission of impulses between nerve cells in some parts of the central nervous system, such as the sensory motor area of the cerebral cortex, especially the pyramidal cells in the deep cortex, the caudate nucleus and the thalamus. The transmission of cholinergic nerves must be combined with cholinergic receptors to produce effects. Cholinergic receptors are divided into muscarinic and nicotinic types; the former is distributed in the myocardial smooth muscle glands innervated by cholinergic postganglionic fibers Equivalent organ, the latter is distributed in the autonomic ganglia and the motor endplate of skeletal muscle. Under normal circumstances, the released acetylcholine is rapidly decomposed by the acetylcholinesterase present in the tissue after completing its physiological function and loses its effect.
After the organophosphorus enters the human body, its phosphoryl group is covalently combined with the active part of the enzyme to form phosphorylated cholinesterase, and the ability to decompose acetylcholine is lost, so that a large amount of acetylcholine accumulates in the body and inhibits the only activity of acetylcholinesterase, making the central The nervous system and cholinergic nerves are over-excited, and finally into depression and failure, showing a series of symptoms and signs.