Muscle Tissue Definition
Muscle tissue comprised of muscle cells (called myocytes). And each myocyte, in turn, consists of several chains of myofibrils. The myofibrils consist of repeating sections of the sarcomere, which is the basic unit of a muscle.
Muscle tissue is the specialized tissue that is found in animals and works by contraction, applying forces to various parts of the body. Muscle tissue consists of muscle cell fibers that are joined together by sheets and fibers. Together, these sheets and fibers, known as muscles, control the movements of an organism and many other contraction functions. Three different types of muscles are found in animals, depending on their use. Although these muscles differ slightly, they function similarly.
Muscle Tissue Function
Muscle tissue acts as a single unit and is often connected to the same nerve bundles. A nerve impulse that travels through the brain or any other external signal tells the muscle to contract. The nerve impulse is transferred almost immediately to all the nerve cells in the muscle tissue, and the entire muscle contracts.
At the cellular level, each muscle cell has a complex of proteins that contain actin and myosin. These proteins come from each other when a contract signal is received. The filaments are attached to the ends of the cells, and as they slide together, the cell shrinks in length.
A single cell can contract up to 70% in length, shortening the entire muscle when it contracts. Muscle tissue can be used to move bones, compress cells, or squeeze various organs. These different types of muscle tissue are discussed below.
Types of Muscle Tissue
There are three types of muscle tissues:
- Skeletal muscle (or striated voluntary muscle) tissue
- Smooth muscle (or non-striated involuntary muscle) tissue
- Heart muscle (or heart muscle) tissue
Skeletal Muscle Tissue
Skeletal muscle tissue is a type of striated muscle, which means that clear bands can be seen under a microscope. This can be seen in the image below (a). These small light and dark bands are highly organized packages of sarcomeres, actin, myosin, and associated proteins. These organized packages allow the striated muscles to contract rapidly and release quickly. Muscle tissue is attached to bones through tendons, which are highly elastic parts of connective tissue.
It can take many muscles to control a single appendix, but in fact, each one controls a small aspect of the movement. Skeletal muscle tissue can be voluntarily controlled by the somatic nervous system. Other types of muscles are mainly controlled by the involuntary or autonomic nervous system.
A sarcomere is defined as the area of a myofibril between two structures of the cytoskeleton called the Z disk (also known as the Z lines), and the streaky appearance of skeletal muscle fibers within each sarcomere. Thick and thin are caused by the arrangement of myofilaments. Dark striped band A is composed of thick fibers containing myosin, which extends into the center of the sarcomere and extends into the matrix.
The thick fibers are anchored in the middle of the sarcomere (line M) by a protein called monoamine. The lighter regions of a band I contain thin actin filaments anchored in the Z disk by a protein called α-actinin. Thin filaments extend within band A toward line M and overlap with thicker filament regions. Band A is dark due to overlap with the thick band myosin filaments as well as the actin filaments. Zone H in the middle of band A is slightly lighter in color because the thin filaments do not expand in this region.
Since a sarcomere is defined by a Z disk, a single sarcomere has a dark A band, half of which is each l band.) During contraction, the myofilaments themselves do not change length, but slide with each other so that the distance between the shorts of disk Z.
The length of band A does not change (the thick myosin filament remains a constant length), but zone H and region of the band I contract. These regions represent areas where the filaments do not overlap, and the filament overlap increases during contraction, and these non-overlapping areas decrease.
Thin filaments are made up of two filamentous actin chains (F-actin), which contain individual actin proteins. These thin filaments anchor in the Z disk and move toward the center of the sarcomere. Within the filament, each globular actin monomer (actin G) has a myosin binding site and is also associated with regulatory proteins, troponin and tropomyosin.
The troponin protein complex consists of three polypeptides. Troponin I (TnI) binds to actin, troponin T (TnT) binds to tropomyosin and troponin C (TnC) to calcium ions. Troponin and tropomyosin move and regulate actin filaments when actin-binding sites bind to myosin.
Coarse myofilaments are made up of myosin protein complexes, which are made up of six proteins: two myosin heavy chains and four light chain molecules. Heavy chains have a tail region, a flexible hinge region, and a spherical head that has an actin-binding site and a binding site for the high-energy ATP molecule.
The light chain plays a regulatory role in the hinge region, but the head region of the heavy chain interacts with actin and is the most important factor in generating force. Hundreds of myosin proteins are arranged in each thick filament, moving toward the M line and heading toward the Z disk.
Other structural proteins are associated with the sarcomere but do not play a direct role in the production of active force. Titin, which is the largest known protein, helps align the thick filament and adds an elastic element to the cam.
Titin is anchored in the M line, runs the length of the myosin, and extends to the Z disk. The thin fibers also contain a stable protein, called a nebulin, that extends the length of the thick fibers.
Cardiac Muscle Tissue
Although the striae in skeletal muscle tissue are similar and parallel, complex, branching streaks are seen in heart muscle tissue. The heart muscle can be seen at the bottom. Although strikes are more difficult to see in this image, the branched nature of cells is easy to extrapolate. Branching occurs because the heart muscle cells are interconnected. The cells are connected through interconnected disks. These junctions help the heart muscle contract as one and provide a rapid, coordinated contraction to move blood.
Smooth Muscle Tissue
Unlike the heart and skeletal muscle tissue, smooth muscle tissue has no strike. The myosin and actin fibers in smooth muscle fibers are not as organized as in other types of muscle tissue. In smooth muscle, contractions do not occur quickly and quickly but are smooth and continuous. Smooth muscle is found around many organs, blood vessels, and other vessels used to transport fluid. Smooth muscle can contract to exert a force on the organ. It can be used to transfer blood or food to their respective systems. Smooth muscle is recognizable by a lack of bump and excruciating nature.
Muscle Tissue, Function, Types, and Components