T. S. of Bone- Mammal
• A connective tissue that consists of cells, connective tissue fibers, neurovascular supply and
extracellular matrix.
• Four types of cells are present in bone tissue: osteogenic cells, osteoblasts, osteocytes and
osteoclasts.
• Osteogenic cells are derived from mesenchyme, found along the inner portion of the
periosteum and divide to give rise of osteoblasts.
• Osteoblasts are bone building cells located are the bone surfaces. They synthesize and secrete
collagen fibers and initiate calcification. As osteoblasts surround themselves with extracellular
matrix, they become trapped in their secretions and become osteocytes.
• Osteocytes are mature bone cells, branched, located in lacunae, and use canaliculi for
communication and exchange of nutrients and wastes.
• Osteoclasts are huge multinucleated cells derived from fusion of monocytes and concentrated
in the endosteum. These cells release powerful lysosomal enzymes and acids that breakdown
the extracellular matrix. These cells help in reabsorption (removal of bone), remodelling and
repairing of bone.
• The extracellular matrix is made up of water, collagen fiber and crystallized mineral salts like
calcium phosphate, calcium hydroxide, calcium carbonate and ions as magnesium, fluoride,
potassium and sulphate.
• The structural unit of a compact bone matrix are the osteons (Haversian systems). Each osteon
consists of layers of concentric lamellae arranged around a central (Haversian) canal.
• Lamellae are thin plates of bone that contain osteocytes in almond-shaped space called
lacunae. Radiating from each lacuna in all directions are tiny canals, called canaliculi.
• Blood vessels, lymphatic vessels and nerves from the periosteum penetrate compact bone
through transverse perforating or Volkmann’s canals.
Functional correlation:
• Compact bone is strongest form of bone tissue and provides protection, support and resists the
stresses produced by weight and movement.
• Serve as a rigid skeleton for the body, and provide attachment sites for muscles and organs.
• Bone also protects the brain in the skull, heart and lungs in the thorax, and urinary and
reproductive organs between the pelvic bones. In addition, bones function in hemopoiesis
(blood cell formation), and serve as crucial reservoirs for calcium, phosphate, and other
minerals.
• Hormones regulate both the calcium release into the bloodstream and its deposition in the bone.
When calcium level falls below the normal, parathyroid hormone, indirectly promotes an
increase in osteoclast numbers. This action induces increased breakdown of bone matrix by the
osteoclast and release of calcium and vise versa done by calcitonin hormone released from
thyroid gland.
• A connective tissue that consists of cells, connective tissue fibers, neurovascular supply and
extracellular matrix.
• Four types of cells are present in bone tissue: osteogenic cells, osteoblasts, osteocytes and
osteoclasts.
• Osteogenic cells are derived from mesenchyme, found along the inner portion of the
periosteum and divide to give rise of osteoblasts.
• Osteoblasts are bone building cells located are the bone surfaces. They synthesize and secrete
collagen fibers and initiate calcification. As osteoblasts surround themselves with extracellular
matrix, they become trapped in their secretions and become osteocytes.
• Osteocytes are mature bone cells, branched, located in lacunae, and use canaliculi for
communication and exchange of nutrients and wastes.
• Osteoclasts are huge multinucleated cells derived from fusion of monocytes and concentrated
in the endosteum. These cells release powerful lysosomal enzymes and acids that breakdown
the extracellular matrix. These cells help in reabsorption (removal of bone), remodelling and
repairing of bone.
• The extracellular matrix is made up of water, collagen fiber and crystallized mineral salts like
calcium phosphate, calcium hydroxide, calcium carbonate and ions as magnesium, fluoride,
potassium and sulphate.
• The structural unit of a compact bone matrix are the osteons (Haversian systems). Each osteon
consists of layers of concentric lamellae arranged around a central (Haversian) canal.
• Lamellae are thin plates of bone that contain osteocytes in almond-shaped space called
lacunae. Radiating from each lacuna in all directions are tiny canals, called canaliculi.
• Blood vessels, lymphatic vessels and nerves from the periosteum penetrate compact bone
through transverse perforating or Volkmann’s canals.
Functional correlation:
• Compact bone is strongest form of bone tissue and provides protection, support and resists the
stresses produced by weight and movement.
• Serve as a rigid skeleton for the body, and provide attachment sites for muscles and organs.
• Bone also protects the brain in the skull, heart and lungs in the thorax, and urinary and
reproductive organs between the pelvic bones. In addition, bones function in hemopoiesis
(blood cell formation), and serve as crucial reservoirs for calcium, phosphate, and other
minerals.
• Hormones regulate both the calcium release into the bloodstream and its deposition in the bone.
When calcium level falls below the normal, parathyroid hormone, indirectly promotes an
increase in osteoclast numbers. This action induces increased breakdown of bone matrix by the
osteoclast and release of calcium and vise versa done by calcitonin hormone released from
thyroid gland.
