Connective Tissue Overview

Overview

This lecture introduces the four main types of connective tissue, their structural components, specific varieties, and primary functions in the body.

The four main types are connective tissue proper, cartilage, bone, and blood.
Connective tissue functions include binding, support, protection, insulation, storage, and transport of substances.
All connective tissues derive from embryonic mesenchyme and contain cells plus an extensive extracellular matrix.

The extracellular matrix consists of ground substance and fibers.
Ground substance fills spaces between cells and contains fluid, adhesion proteins, and proteoglycans.
Three main fiber types: collagen (strongest), elastic (stretchy), and reticular (network-supporting).
Connective tissue cells are either immature ("-blast" suffix, forming matrix) or mature ("-cyte" suffix, maintain matrix).

Divided into loose (areolar, adipose, reticular) and dense (regular, irregular, elastic) connective tissue.
Areolar: cushions, supports, stores fluids; most abundant.
Adipose: stores fat and insulates.
Reticular: supports certain structures with reticular fibers.
Dense regular: parallel collagen, resists tension, found in tendons/ligaments.
Dense irregular: collagen in various directions, resists tension from many directions.
Dense elastic: similar to regular but more elastic fibers.

Cartilage withstands tension and compression; lacks nerves and blood vessels and gets nutrients via diffusion.
Hyaline cartilage: most abundant, firm, cushions and reinforces.
Elastic cartilage: more elastic fibers, found in the ear.
Fibrocartilage: alternating rows of chondrocytes and collagen, compressible and strong, found in intervertebral discs.

Bone (osseous tissue) matrix contains collagen and inorganic calcium salts, making it hard; has blood vessels.
Blood, though fluid, is considered connective tissue due to mesenchymal origin; consists of cells in plasma.

Mesenchyme — embryonic tissue from which all connective tissues derive.
Extracellular matrix — network of ground substance and fibers outside the cells.
Collagen fibers — strong protein fibers that resist tearing.
Elastic fibers — stretchy fibers made of elastin.
Reticular fibers — thin fibers forming supportive networks.
Fibroblast/Chondroblast/Osteoblast — immature matrix-secreting cells for connective, cartilage, and bone tissue, respectively.
Fibrocyte/Chondrocyte/Osteocyte — mature connective, cartilage, and bone cells.