The Connective Tissue
Definition
A tissue which supports other tissues which make up the body
It is one of the four basic tissue types : epithelial tissue, muscle tissue, nerve tissue and connective tissue
It forms a framework upon which epithelial tissue rests and witiin which nerve tissue and muscle tissue are embedded. Blood vessels and nerves travel through connective tissue
Provides mechanical suppoort for other tissues
provides a way for communication and transport among other tissues
It is the stage for inflammation
It is derived from mesenchyme of the embryo
Classification
The various classifications are :-
- ordinary / Special
- loose / dense
- regular / irregular
- fibrous, elastic, adipose, lymphoid, areolar, blood, bone and cartilage
The term connective tissue routinely refers to ordinary connective tissue while the special forms are more commonly referred to by thir specific names (e.g., bone, cartilage, blood)
Structure
Connective tissue consists of
- cells of several types
- extracellular fibers
- extracellular ground substance
Cells
fbroblasts, adipocytes, macrophages, mast cells, lymphocytes, other cells
Matrix - collagen fibers, reticular fibers, elastic fibers, ground substance ( )
Unlike cells of epithelial cells connective tissue cells are not directly attached to one another
Individual connective tissue cells are normally separated from one another by varying amounts of extracellular matrix.
The most common connective tissue cells are :
fibroblasts
adipocytes
mast cells, macrophages and lymphocytes
characteristic connective tissue cell types include both resident cells and immigrant or wandering cells
resident cells are - fibroblasts, adipocytes, mast cells, macrphages
immigrant cells are : lymphocytes, monocytes and neutrophils
Matrix
connective tissue matrix is composed of ground substance and fibers
ground substance consists of water stabilized by glycosaminoglycans, proteoglycans and glycoproteins; in bone ground substance includes minerals
in blood the ground substance is fluid (plasma)
Fibers
the principal fiber type is collagen (flexibility and tensile strength)
the matrix is produced by fibroblasts/chondroblasts/osteoblasts
Functions
Supports all the other tissues - other tissues ae either supported upon connective tissue (epithelium), invaginated into connective tissue (glandular epithelium) or embedded witin the connective tissue (blood vessels, muscles, and nerves)
Transports nutrients and metabolits
Immunological defense
Mechanical support
Tissue repair
Reserve energy storage (fat)
Heat generation (brown fat)
Haemopoiesis
