class 11th, Connective Tissue, part – 4

Connective tissue proper: it holds various tissues together in any organ. It is further divided into three types:

Areolar – it is found below the skin, in kidney and around the mussel.  It helps to hold various tissues together. These cells have Mast cells that concerned with the allergy.  The areolar tissue joins different tissues forms the packing between them and helps to keep the organs in place an in normal shape. The areolar tissue contains three types of cells fibroblast, macrophages and mast cells. Fibroblasts synthesize two kinds of proteins-collagen and elastin.

  • Fibroblast secretes the major amount of matrix.
  • Macrophage / Histiocytes / Clasmocytes: They are phagocytic in nature.
  • Mast cells / Mastocytes: They are irregularly ovoid cells and contain basophilic granules.

White fibrous tissues – its matrix contain white fibres that make it inelastic. Sheets of these tissues are found to cover the bones, cartilage, kidney, etc.  The presence of white fibrous tissue at the joints between skull bones makes them immovable. Bundles of these tissues called Tendons.

Yellow fibrous connective tissues – these tissues are very elastic. Sheets of these tissues cover up the blood vessels. Bundles of these tissues called ligament. The ligament connects bones at the joints and holds them in position.

Adipose tissues – it is modified Areolar tissues in which the cell becomes very large and become oval. Cells are called adiposities.  It is found below the skin, around heart brain and below the eye balls. It helps in storage of food in the form of fats. It act as insulators and prevents loss of heat.

Skeletal tissues: it is the hard connective tissues that forms supportive framework of body. It is of two types:

Cartilage – this tissue is elastic, harder than connective tissue proper but softer than bone. Its elasticity is due to presence of protein chondrin. Spaces in its matrix are called lacunae, which contain cartilage forming cells called Chondrocytes. It is of three type’s hyaline, fibrous and calcified. It form supportive framework of nose, pinna, etc. Elastic Cartilage contains a dense network of elastic fibers between scattered chondrocytes. It forms the Eustachian tube, epiglottis and pinna of ear. The elastic fibers make those organs considerably elastic and pliable. Calcified Cartilage – Initially it is like hyaline cartilage but later on it gets hardened like bone due to deposition of Calcium salts for example, supra scapula of frogs pectoral girdle, pubis of pelvic girdle of frog.