Biochemistry

Hormone-like substances are synthesized in nerve cells that act as neurotransmitters or neurohormones. The function of neurohormones includes the transmission of a chemical signal at a distance from the place of formation and excretion, and neurotransmitters provide the transmission of a nerve impulse to a neighboring cell. 13.2 ROLE OF THE NERVOUS SYSTEM IN REGULATION EXCHANGE OF SUBSTANCES A structural element of the nervous system is a nerve cell - a neuron. Neurons connect with each other and with various organs and tissues by dendrite. Between neurodendrite that transmit and receive signals, there are gaps filled with interstitial fluid, which are called "synapses". They contain chemical compounds - “ transmitters ” - neurotransmitters, with the help of which a signal is transmitted from one neuron to another. Some neurotransmitters activate the excitation of metabolism and functions in the corresponding system, others - cause inhibition. Excitatory neurotransmitters include acetylcholine, noradrenaline, adrenaline, dopamine, serotonin, histamine', inhibitory neurotransmitters include - y-aminobutyric acid (GABA), glycine. Acetylcholine is one of the most universal mediators. It is synthesized from choline and acetyl-CoA with the participation of the choline acetyltransferase enzyme, as well as Mg 2+ , К + and Ca 2+ . (CH 3 ) 3 N + - CH 2 - CH 2 - OH + CH 3 - CO - SKoA -> Choline Acetyl - CoA (CH 3 ) 3 N + - CH 2 - CH 2 - О - CO - CH 3 + HSKoA Acetylcholine Acetylcholine excites neurons that regulate skeletal muscle movements and the function of certain parts of the central nervous system. Nerve endings containing acetylcholine are called cholinergic. They contain not only enzymes that ensure the synthesis of acetylcholine, but also an enzyme that catalyzes its breakdown - acetylcholinesterase. As a result of the acetylcholine breakdown, its mediator function ceases. Thus, dynamics of the acetylcholine content in the nervous system, and therefore its regulatory effect on various organs, depend on the activity of АСҺЕ. Noradrenaline is one of the highly active mediators, especially in the transmission of nerve impulses in the peripheral nervous system. It is formed from the amino acid tyrosine. 278