Soft tissues include all soft tissues except epithelia, internal organs, and glial tissue. Thus, adipose tissue, muscle tissue, and connective tissue are included in soft tissues.
What is soft tissue?
Soft tissue refers to a collection of differentiated cells including their extracellular matrix. Soft tissues are usually composed of collagen, elastin, and a ground substance. Because of this special makeup, soft tissues can easily deform and then return to their original shape. Soft tissues are also viscoelastic. In other words, they have both elastic and viscous material behavior. They are also incompressible. This means that they do not change their volume even when subjected to pressure at a constant temperature. Thus, they cannot be compressed. Another property of soft tissues is anisotropy. Soft tissues are found in many parts of the body. For example, muscle tissue, connective tissue, and adipose tissue are all soft tissues.
Anatomy and structure
Adipose tissue is formed from adipocytes. These are quite large cells whose cell body is filled with a thick drop of lipid. Adipocytes are therefore also called univacuolar fat cells. The cell nucleus is pushed to the edge by the thick vacuole of fat. Cell organelles or cell fluid are not visible due to the fat filling of the cell. The fat vacuole is freely present in the cell fluid. The individual adipocytes are incorporated into a fibrous scaffold and surrounded by a basal lamina and reticular fibers. These fibers hold the fat cells in shape even when force is applied. A distinction can be made between yellow and white fat. Muscle tissue is divided into skeletal muscle, cardiac muscle, and smooth muscle. Skeletal muscle consists of several muscle fiber bundles, which in turn consist of individual muscle fibers. The individual muscle fibers can be up to 15 centimeters long. They are encased in connective tissue called fascia. The individual skeletal muscle in its entirety is also surrounded by connective tissue. From this, septa extend into the interior of the muscle. Each muscle fiber consists of thousands of myofibrils. These pass through the muscle fiber and are in turn made up of smaller units called myofilaments. The myofilaments are arranged in sarcomeres. Because of this arrangement, skeletal muscle appears striated under the microscope. It is therefore also called striated muscle. Smooth muscle can be distinguished from striated muscle. In contrast to striated muscle, there is no regular arrangement of myofibrils in smooth muscle. Smooth muscle is formed mainly from actin and myosin filaments. Cardiac muscle is formed from a special type of muscle. It is a striated muscle that cannot be consciously controlled. The term connective tissue covers various types of tissue, all of which contain comparatively few cells. On the other hand, connective tissue contains all the more interstitial cell substance. Various fibers are embedded in the intercellular substance. The main part is made up of collagens. These form a dense meshwork. The space between the collagenous fibers is filled by proteoglycans.
Function and tasks
The tasks and functions of soft tissue vary according to the type of tissue. Smooth muscle provides for the movement of organs. For example, it is an important part of digestion or breathing. Smooth muscle works slowly and persistently and functions completely independently of human will. The striated musculature can be influenced voluntarily. It forms more than 400 different skeletal muscles. These enable various movements. Frequently, several muscles are involved in a movement sequence. The skeletal muscles work quickly, but tire more easily. The heart muscles have a special position. Although it is striated, it cannot be influenced voluntarily. The cardiac musculature ensures the contraction of the heart and thus the ejection of blood into the circulation. It thus enables the supply of blood to the body. Fatty tissue can perform various tasks. In the fat bodies, the building fat serves as padding for the organs and also functions as a shifting layer. Storage fat serves to store energy from food.While white and yellow adipose tissue form the storage fat, brown adipose tissue is used for heat generation. Connective tissue can also perform various functions. Depending on its occurrence, it protects and surrounds organs, acts as a sliding and displacement layer just like fatty tissue, or serves as a conductive structure for pathways. It is also involved in the production and storage of various substances. It further serves as a support structure for the body.
Diseases
Depending on the soft tissue, various diseases may occur. The term collagenoses covers diseases in which the immune system is directed against the body’s own connective tissue. Collagenoses include, for example, Sjögren’s syndrome, scleroderma, systemic lupus erythematosus and polymyositis. The appearance of collagenoses varies from disease to disease. For example, Sjögren’s syndrome is noticeable by dry eyes, dry mouth, and decreased lacrimation. In scleroderma, on the other hand, the connective tissue hardens, resulting in mimic rigidity in the facial area and a reduction in the size of the mouth opening. A quite frequent disease of the fatty tissue is lipedema. In this disease, fatty tissue accumulates on the sides of the thighs and hips. The upper arms, lower legs and neck can also be affected by the atypical, symmetrical accumulation of fat. The swellings are accompanied by pain, tenderness and a tendency to hematoma. Lipedema affects almost exclusively women.
