Describe the characteristics and types of connective tissue.

(N/A) Connective tissues are the most abundant and widely distributed in the body of complex animals. They are named connective tissues because of their special function of linking and supporting other tissues/organs of the body.
Characteristics:
$1$. They consist of a few cells and a large amount of intercellular ground substance.
$2$. The cells secrete structural protein fibres called collagen or elastin,which provide strength,elasticity,and flexibility.
$3$. The cells also secrete modified polysaccharides,which accumulate between cells and fibres and act as a matrix.
Types of Connective Tissue:
Connective tissue is classified into three types:
$(i)$ Loose connective tissue
(ii) Dense connective tissue
(iii) Specialised connective tissue
$(i)$ Loose Connective Tissue: Cells and fibres are loosely arranged in a semi-fluid ground substance. Examples include:
$(a)$ Areolar tissue: Present beneath the skin. It serves as a support framework for epithelium.
$(b)$ Adipose tissue: Located mainly beneath the skin. The cells are specialised to store fats.
(ii) Dense Connective Tissue: Fibres and fibroblasts are compactly packed. It is of two types:
$(a)$ Dense regular: Collagen fibres are present in rows between many parallel bundles of fibres (e.g.,tendons and ligaments).
$(b)$ Dense irregular: Fibroblasts and many fibres (mostly collagen) are oriented differently.
(iii) Specialised Connective Tissue:
$(a)$ Cartilage: The intercellular material is solid and pliable and resists compression. Cells are called chondrocytes.
$(b)$ Bone: It has a hard and non-pliable ground substance rich in calcium salts and collagen fibres which give bone its strength. Cells are called osteocytes.
$(c)$ Blood: $A$ fluid connective tissue containing plasma,red blood cells (RBCs),white blood cells (WBCs),and platelets.