Question

Draw a labelled diagram of T.S of bone.

Answer 1

Hint: Bone: It is the hard-connective tissue. It is a very strong and non-flexible tissue. It is made up of 70% inorganic matter and 30% organic matter. If bone is put in HCl it gets decalcified and becomes soft and flexible and nothing is happened to it if put in KOH.

Complete answer:
Structure of a bone:
 The matrix of bone is very hard and non-pliable because of the presence of salts, such as calcium phosphate, calcium carbonate, etc. and proteins like ossein and collagen fibres.
 Calcium salts and collagen fibres give bone its strength.
 In the solid matrix longitudinal canals are present called haversian canals.
 Each haversian canal contains an artery, a vein, a lymph vessel, a nerve and some bone cells, all packed within connective tissue. The matrix is present in the form of layers called lamellae.
In these lamellae are present ring-shaped fluid-filled spaces called lacunae. The lacunae contain bone cells, called osteocytes.

 In long bones such as limb bones, a cavity called bone marrow cavity is present. This cavity is filled with a soft and semisolid fatty tissue termed as bone marrow.
The bone marrow in some bones is the site of production of blood cells (such as RBCs, WBCs, Platelets etc.)

Note: Bone performs many functions as:-
 It provides a structural framework to the body. It supports and protects soft tissues and organs, such as the brain, lungs etc. It provides surface for the attachment of muscles and thus helps in locomotion/ movement. It serves as a storage site for calcium and phosphate.