MEDICAL BIOLOGY, HUMAN ANATOMY, PHYSIOLOGY AND PATHOLOGY - Ya.I. Fedoniuk 2010

BIOLOGY

CHAPTER 1. BIOLOGICAL FOUNDATIONS OF HUMAN VITAL ACTIVITY

1.2. CELL. TISSUES. CONCEPT OF AN ORGAN, ORGAN SYSTEM, ORGANISM

CONNECTIVE TISSUE

1. Fibrous Connective Tissue

Depending on the content of fibrous structures, fibrous connective tissue is classified into loose and dense. Loose connective tissue contains relatively more Cells and ground substance, whereas Cytology/practical/45.html">Dense connective tissue is rich in fibrous structures.

According to the arrangement of fibrous structures, Dense Fibrous Connective tissue is subdivided into regular and irregular: in regular tissue, the fibers run parallel to one another, whereas in irregular tissue, they extend in various directions.

Loose fibrous connective tissue accompanies nerves and Blood Vessels and forms the stroma of Organs. Its intercellular matrix contains Collagen, elastic, and reticular fibers. Collagen fibers are composed of the protein collagen, while elastic fibers consist of Elastin. Collagen fibers are extremely strong, providing the mechanical properties of connective tissue. Elastic fibers impart elasticity to the tissue, allowing it to stretch and subsequently return to its original dimensions.

Reticular fibers perform a supportive function, form networks, and are particularly well-developed in hemopoietic organs. The ground (amorphous) substance, in which the cells and fibers of the connective tissue are embedded, is a gel of specific viscosity and chemical composition. It consists of Water, Proteins, Lipids, Polysaccharides, and minerals. The content and COMPOSITION OF THE ground substance vary across Different types of connective tissue.

The cells of loose connective tissue include fibroblasts, macrophages, plasmocytes, tissue basophils, pigment cells, adventitial cells, fat cells, and reticular cells, as well as leukocytes migrating from the blood (Fig. 1.8).

Class="center">

Fig. 1.8. Loose fibrous connective tissue: 1 - fibroblast; 2 - macrophage; 3 - plasmocyte; 4 - tissue basophil; 5 - lymphocyte; 6 - neutrophilic granulocyte; 7 - adipocyte; 8 - adventitial Cell; 9 - collagen fiber; 10 - elastic fiber.

Dense fibrous connective tissue is characterized by a high content of fibers (predominantly collagenous) and a low content of the amorphous component within the intercellular matrix. Among the sparse cell population, fibrocytes predominate. This structural feature ensures high mechanical strength. Depending on fiber orientation, dense fibrous connective tissue is categorized into regular and irregular types.

Regular dense fibrous connective tissue is found in fibrous membranes, ligaments, and tendons. The latter, connecting Muscles to bones, experience mechanical force vectors acting primarily in a single direction. This factor determines the strictly parallel spatial orientation of collagen fiber bundles.

An example of irregular dense fibrous connective tissue is the reticular layer of the dermis. In this layer, thick bundles of collagen fibers run in various directions, providing the Skin with resistance to mechanical stress applied from multiple directions.