connective tissues3

? General Features
1. Contain three basic elements: cells, ground substance and fibers (Extracellular Matrix).
2. Matrix which may be fluid, semi-fluid, gelatinous, fibrous or calcified is usually secreted by the connective tissue cells
3. Do not usually occur on free surfaces.
4. Have a nerve supply.
5. Highly vascular.
6. Cells in connective tissue are derived form mesenchymal cells.

? Composition
• Cells of connective tissues:

Type of cells Description Distribution Function
Fibroblasts, chondroblast, & osteoblast Large, flat Most numerous connective tissue cells Secrete fibers and ground substances into the matrix
Macrophages Rounded contain phogocytosed material
Lungs and spleen
Capable of engulfing bacteria and cellular debris through phagocytosis

Plasma Cells
Small cells, oval-shaped cells gastrointestinal and respiratory tracts Secrete antibodies

Mast cells and basophiles
Round to oval-shaped cells
Abundant near blood vessels
Produce histamine

Adipocytes
Flattened peripheral nucleus
Below the skin and around organs
Store neutral fats

White Blood cells
(Neutrophils and eosinophlis)
Generally spherical cells gather at sites of infection
Phagocytosis and participate in inflammatory reaction
Lymphocyte Small spherical cells with indentation Lymphatic tissues Production of immunocompetent cells

• Ground substance: an amorphous substance contain water and large molecules such as polysaccharide and proteins. Its functions:
o Supports cells.
o binds cells together.
o Provides medium for substance exchange.

• Fibers: there are 3 types of fibers collagen, elastic, and reticular fiber





Type of fiber Composition Properties Distribution Function
Collagen Collagen I, II Inelastic, eosinophilic bone, cartilage, tendons, ligaments
Strong, resist pulling forces.
Promote flexibility and toughness.

Reticular Collagen III Inelastic, branched, argyrophilic blood vessels
spleen, lymph nodes Support walls of blood vessels.
Supporting framework for soft organs.
Elastic elastin and fibrillin Elastic, eosinophilic skin, blood vessel walls, and lung tissue Promote resilience.