Chapter 3 - Connective Tissue
Connective tissue supports and protects organ. It has three primary components: fibers, extracellular matrix and cells. The proportion of these elements is the basis of which the connective tissues are classified.
This chapter examines the basic types of connective tissue, while subsequent chapters examine specialized connective tissues such as cartilage, bone and blood.
Connective tissue fibers provide general support for other tissues. Three types of fibers occur in connective tissue: collagen, elastic and reticular.
Collagen is the most abundant structural protein in connective tissues.
CELLS OF CONNECTIVE TISSUE
Although connective tissue has fewer cells than most tissues, the cells found in connective tissue are extremely important. Fibroblasts and adipocytes do not leave connective tissue.
Fibroblasts are widely distributed within connective tissue and synthesize the components of the extracellular matrix. They are also capable of differentiating into other types of connective tissue cells
Adipocytes (or fat cells) are specialized for the synthesis and storage of lipids. They may occur singly but are more often found in clusters within loose connective tissue.
IMMUNE CELLS OF CONNECTIVE TISSUE
Neutrophils, eosinophils, basophils, lymphocytes, and monocytes are immune cells that migrate from blood into connective tissue.
Eosinophils are involved in many inflammatory processes, including parasitic infections, alleregic diseases, and asthma.
Mast cells are widely distributed in connective tissue. The release molecules that dilate blood vessels allowing the recruitment of more immune cells to an infection.
Mast cells undergo rapid degranulation during an anaphylactic reaction.
Lymophocytes develop the ability to recognize and respond to antigens. Their number increases dramatically at sites of inflammation.
Plasma cells produce large quantities antibodies against specific antigens. They are widely distributed in connective tissue, especially in the gastrointestinal tract
Macrophages are avidly phagocytic cells that engulf and digest microbes, cellular debris and foreign substances.
Mast Cell / Plasma Cells / Eosinophils
Example of multiple types of immune cells in connective tissue.