6.3 Histology of Bone Tissue

Collagen fibers

A bone's flexibility depends on its ___________________.

Crystallized inorganic mineral salts

A bone's hardness depends on the ____________________.

Calcification

As mineral salts are deposited in the framework formed by the collagen fibers of the extracellular matrix, they crystallize and the tissue hardens. This process is called _______________ and is initiated by bone-building cells called osteoblasts.

Osteons or Haversian systems

Cylindrical structures that comprise compact bone are called ___________________

Concentric lamellae

Layers of mineralized extracellular matrix (bony matrix) around a central canal are called ______________.

Osteoprogenitor cells, osteoblasts, osteocytes and osteoclasts.

Name the four types of cells that are present in bone tissue:

Lacunae

Small cavities in between the concentric lamellae that contain osteocytes are called ____________________.

Trabeculae

Spongy bone tissue consists of lamellae that are arranged in an irregular pattern called ________________. It contains macroscopic spaces that are filled with red bone marrow and yellow bone marrow.

Osteonic canal

The central canal in the osteon which contains a blood vessel, interconnected by Volkmann's canals is called _________________.

Bone resorption

The removal of minerals and collagen fibers from bone by osteoclasts is termed ________________________.

Spongy Bone tissue

__________ also referred to as trabecular or cancellous bone tissue does not contain osteons, and is ALWAYS located in the interior of bone.

Osteocytes

___________ are mature bones cells that maintain its daily metabolism. They do not undergo cell division.

Compact bone tissue

___________ contains few spaces and is the strongest form of bone tissue. Additional notes: Found beneath the periosteum of all bones. Provides protection, support and resists stresses.

Osteoblasts

_____________ are bone-building cells. They synthesize and secret collagen fibers and other organic components required to build the extracellular matrix of bone tissue. They also initiate calcification. Additional notes: Surround themselves with extracellular matrix, and become trapped in their secretions and become osteocytes.

Osteoclasts

______________ are huge cells derived from the fusion of as many as 50 monocytes. The ruffled border of the cells release a powerful lysosomal enzyme that digest the protein and mineral components of the extracellular matrix.

Perforating (Sharpey's) fibers (Compact bone)

______________ connect circumferential lamellae to the periosteum.

Canaliculi

________________ are hair-like canals that connect lacunae to each other and the central canal. Fingerlike processes of osteocytes project through these channels and communicate with neighboring osteocytes.

Interosteonic canals (Volkman's or perforating cells)

________________ are transverse canals that penetrate the compact bone and contain blood vessels and nerves which connect with those of the medullary cavity, periosteum and central canals.

Osteoprogenitor cells

________________ are unspecialized bone stem cells derived from mesenchyme. They are the only bones cells to undergo cell division. Additional notes: Found along the inner portion of the periosteum, in the endosteum and in the canals within the bone.

Circumferential lamellae (Compact bone)

_________________ are located deep to periosteum and superficial to endosteum and extend around entire circumference of the diaphysis and resist twisting of long bone. Additional notes: - They develop during initial bone formation. - The circumferential lamellae directly deep to the periosteum are called external circumferential lamellae. They are connected to the periosteum by perforating (Sharpey's) fibers. - The circumferential lamellae that line the medullary cavity are called internal circumferential lamellae

Hydroxyapatite

_________________ is the compound of calcium and phosphorous that makes up bone.

Interstitial lamellae

____________________ are fragments of older osteons that have been partially destroyed during bone rebuilding or growth and are the areas between neighboring osteons. Additional notes: - Also have lacunae with osteocytes and canaliculi.