Connective Tissue – Concept, types and functions

We explain what connective tissue is and how it is classified. Also, what are the various functions of these tissues.

Conjunctive tissue
The connective tissue cells are usually quite far apart.

What is connective tissue?

It is known by the name of connective tissue or connective tissue to a Diverse set of body tissues that fill, support, and connect the body, that is, it connects, separates and supports the various organ systems that make up the body of living beings.

Connective tissue it is generally of the fibrous type (collagen, elastin and reticulin fibers), as well as a matrix of variable consistency composed of water, mineral salts, polypeptides and complex sugars. The cells of the connective tissue are usually quite separate from each other, and may or may not be endowed with specific functions, such as the generation of enzymes, defensive cells or other regulatory substances.

In general, we speak of connective tissue (in the singular) to refer to the set of all connective tissues, whatever they are, which share structural and functional similarities. Blood is a very particular case of liquid matrix connective tissue, too, although it may not seem like it.

Types of connective tissue

Loose connective tissue
Loose connective tissue has a high content of cells.

Connective tissue is classified according to its specialized functions, as follows:

  • Specialized connective tissue. Those connective tissues endowed with unique and particular functions. They are divided into:
    • Loose connective tissue. It has a high content of cells and extracellular components of the matrix, much more abundant than the fibrous content. In turn, it can be of the following types:
      • Mucous connective tissue. An amorphous fundamental substance predominates in them, composed of hyaluronic acid and which has a moderate cellular abundance. It is rare in adults, but abundant in the umbilical cord and to a lesser extent in the pulp of the teeth.
      • Reticular connective tissue. It presents argyrophilic reticular fibers, composed of collagen, forming a network-like framework. Thus are composed, for example, the bone marrow stoma, spleen, and parenchyma.
      • Mesenchymal connective tissue. It is the tissue that makes up the embryonic mesenchyme, they are rich in mesenchymal cells from which the specific cells of each tissue come.
    • Dense or fibrous connective tissue. In which the fibers predominate over the cells, and which is classified in turn into:
      • Regular dense connective tissue. The one that forms the tendons, ligaments and other fibers that support traction and therefore are arranged in the same direction, parallel to each other to achieve greater strength.
      • Irregular dense connective tissue. Made of randomly arranged collagen fibers and little fundamental substance, it provides protection against stretching of the organs, which is why it can be found in the capsule of each one of them.
  • Non-specialized connective tissue. These are support and connection tissues that do not fulfill other specific functions, but rather fill the body. They are classified according to their nature in:
    • Adipose tissue Composed mainly of lipids and / or fats.
    • Cartilaginous tissue. Composed of cartilage, an elastic substance that acts as a cushion between the bones.
    • Woven bone. Composed of mineralized tissues that we call bone.
    • Lymphatic tissue. The one that makes up the lymphatic system, connecting the glands and serving as a transport to the body’s defenses.
    • Blood tissue. The blood and the cells that compose it.

Connective tissue functions

The primary function of the connective tissue is the systemic integration of the organism, that is, provide support, cohesion, separation and serve as a logistical means of communication to the organs and different systems that make up the body. For example, they support and separate the organs in the abdominal cavity, at the same time that they allow the distribution between them of the vascular and nervous structures.

On the other hand, specialized connective tissues they also have hematopoietic, lymphoid or similar functions, contributing to the production of cells of various types or to the production of specific substances for internal regulation of the body.