Sarcoplasmic Reticulum, Sarcoplasmic Reticulum

Sarcoplasmic Reticulum, Sarcoplasmic Reticulum are elements of the endoplasmic reticulum of striated muscle fibers that play an important role in muscle concentration and relaxation. The sarcoplasmic reticulum is the main site of calcium storage in the muscle cell and performs cytoplasmic calcium regulation functions necessary for normal muscle contraction.

The structure of the Sarcoplasmic Reticulum consists of numerous membranous canals and vesicles that penetrate the muscle cell. These channels and vesicles form a complex three-dimensional network that is located near the myofibrils, the main contractile units of muscle tissue.

An important function of the Sarcoplasmic Reticulum is the management of calcium in the muscle cell. During muscle contraction, calcium is released from the Sarcoplasmic Reticulum into the cytoplasm, where it binds to the proteins of the contractile units, which leads to a change in their shape and muscle contraction. After muscle cell contraction, excess calcium is returned to the Sarcoplasmic Reticulum for later use.

In addition, the Sarcoplasmic Reticulum plays an important role in transmitting nerve impulses to the contractile regions of muscle fibers. When a nerve impulse reaches the end of a nerve fiber, it causes the release of a neurotransmitter, which stimulates the Sarcoplasmic Reticulum to release calcium into the cytoplasm. This leads to muscle contraction.

Thus, the Sarcoplasmic Reticulum is an important element of the muscle cell, playing a key role in muscle concentration and relaxation. Its functions are related to the regulation of calcium in the muscle cell, transmission of nerve impulses and ensuring normal muscle contraction.

The sarcoplasmic reticulum (SR) is a network of specialized proteins and lipids found in the sarcoplasm of muscle cells. The SR performs a number of important functions in muscle function, such as transmission of nerve signals to muscle fibers, accumulation and release of calcium ions, regulation of contractile activity, etc.

The SR consists of two main types of structures: tubules and vesicles. The tubules are 0.5 to 1.5 µm long and about 0.2 µm wide. They pass through the entire sarcoplasm, connecting with each other and forming a network. The vesicles have a diameter of about 0.1 μm and contain protein molecules and lipids. They are formed as a result of the fusion of CP tubules and transport calcium ions into cells.

The functioning of the SR is associated with the transmission of nerve signals. When a nerve impulse reaches a muscle fiber, it activates receptors on the muscle fiber membrane. The receptors activate enzymes that cause the release of calcium from the SR. Calcium enters the sarcoplasmic reticulum and activates enzymes responsible for contraction of muscle fibers, which leads to muscle contraction.

In addition, SR is involved in the regulation of muscle contractility. When muscles contract, the SR releases calcium, which activates contractile proteins and causes contraction. When the muscles relax, the SR absorbs calcium from the sarcoplasm, which prevents re-contraction.

Thus, SR plays an important role in muscle function and is a key element in the process of muscle contraction and relaxation. Impaired SR function can lead to various muscle diseases, such as myopathy, myasthenia gravis, etc. Therefore, understanding the mechanisms of SR functioning is of great importance for the development of new methods for the treatment and prevention of muscle diseases.

Sarcoplasmic filaments are part of the system for transmitting nerve impulses to muscle fibers. These fibers are part of the sarcoplasmic reticulum, which is located between the sarcolemma - the outer membrane of the muscle cell - and the adjacent tinctorial membrane, which is a continuation of the outer membrane of the myocyte. The main role of this system is to transmit nerve impulses to muscle cells.

Before the discovery of plasma filaments, it was believed that the muscle was driven by the force of chemical reactions occurring inside the muscle. The decisive moment that predetermined the idea of ​​nervous control of a muscle as muscle power was the discovery by A. Gaston in 1883 of the transmission of one nervous excitation to two successively located muscles through an intermediate metal contact between them. And most importantly, the discoveries of B. Basedov, Luigi Galvani and Alessandro Volta, as a result of which it became clear that electric current can be used to reproduce an impulse. In 1913, the mechanism of transmission of nerve potential was discovered. B. Ganong determined that thanks to small electrometric processes (resting electrical potential - RPP), the muscle fiber membrane is modified and becomes capable of transmitting excitation waves in the form of primary changes in the electrical permeability of muscle filaments during the movement of Na+ or K+ ion molecules through its pores. Thus, the action potential is able to transmit the next wave of excitation, transferring the molecule inside each muscle cell. This means that the transfer of electrical energy to a nerve cell occurs through a narrow gap (pores), and not simply by diffusion, as with the transfer of chemical effects in a muscle. The exciting wave gives biochemical effects, but without the introduction of ions to the walls