Bone Tissue

BONE TISSUE
Bone tissue is a specialized form of connective tissue and is the main element of the skeletal tissues. It is composed of cells and an extracellular matrix in which fibers are embedded. Bone tissue is unlike other connective tissues in that the extracellular matrix becomes calcified.
FUNCTIONS OF BONE TISSUE

• The skeleton is built of bone tissue. Bone provides the internal support of the body and provides sites of attachment of tendons and muscles, essential for locomotion.
• Bone provides protection for the vital organs of the body: the skull protects the brain; the ribs protect the heart and lungs.
• The hematopoietic bone marrow is protected by the surrounding bony tissue.
• The main store of calcium and phosphate is in bone. Bone has several metabolic functions especially in calcium homeostasis.

Bone is a hard, but brittle, tissue and is relatively light per unit volume. Bone is a dynamic tissue, which throughout life bone tissue is continually being formed and resorbed. This remodelling and reorganization of bone tissue is the result of many factors including:

• mechanical stimuli
• metabolic causes (lack of dietary calcium, illness, aging)
• endocrine changes
• effects of drugs.

MACROSCOPIC STRUCTURE OF BONE
There are two main categories of bone :

• Spongy bone (trabecular bone, cancellous bone)
• Compact bone (cortical bone)

Spongy bone
Spongy bone is composed of a lattice or network of branching bone spicules or trabeculae. The spaces between the bone spicules contain bone marrow.
Compact bone
Compact bone appears as a mass of bony tissue lacking spaces visible to the unaided eye

Reference:
www.technion.ac.il