Bone Tissues

Osteoprogenitor cells

unspecialized undergo mitosis and develop into osteoblasts, found in periosteum, endosteum, and canals that contain blood vessels

Osteoblasts

cells that form bone but don’t divide, secrete collagen and other organic bone components, derived from osteoprogenitor cells

Osteocytes

mature, derived from osteoblasts, don’t divide, trapped in bone matrix, don’t secrete matrix material, maintain cellular activities of bone, exchange of nutrients and waste with blood

Osteoclasts

believed to develop from circulating monocytes, settle on bone surface and function in bone reabsorption

Bone tissue matrix

contains mineral salts of tricalcium phosphate (hydoxyapatite) and calcium carbonate, with small amounts of magnesium hydroxide, sulfate, and fluoride

Calcification

process in which salts are deposited in the frame work formed by collagen fibers, salts give the bone hardness and fibers give it tensile strength

Compact (dense) bone tissue

few spaces, make up bulk of diaphysis, gives long bones strength, forms concentric ring structure

Osteon

the basic structural unit of compact bone, target shaped structures made of rings of bone

Haversian (central) Canal

a hole at the center of the osteon, contains blood vessels, lymphatic vessels and nerves

Concentric lamellae

rings of bone around the central canal, make up the osteon

Lacunae

small spaces within the lamellae that house osteocytes

Canaliculi

are small channels which radiate away from the lacunae; they are filled with extracellular fluid and processes from osteocytes

Interstitial lamellae

Arches of bone that fill up the spaces between the osteons

Circumferential lamellae

Arches of bone around the surface of the bones, make the bones surface smooth

Perforating canals

Tubes in the sides of the bones that allow blood vessels, lymphatic vessels and nerves to reach the central canals of the osteon

Spongy bone tissue

does not contain osteons, made of irregular lattice of bone plates called trabeculae, spaces between trabeculae are filled with red bone marrow, in trabeculae are osteocytes in lacunae, radiating from lacunae are canaliculi

Long bones

greater length then width, curved for strength, mostly made of compact bone, but with some spongy bone, ex. thigh, leg, arm, forearm, finger and toes

Short bone

cube shaped, made of spongy bone except at the surface where there is thin layer of compact bone, ex. wrist and ankle bones

Flat bone

thin, composed of two parallel plates of compact bone enclosing a layer of spongy bone, provide protection and places for muscle attachment, ex. cranial bones, sternum, ribs

Irregular bone

complex shape, vary in amount of spongy and compact bone tissue, ex. vertebrae

Suturas bone

small bones found in the sutures of certain cranial bones, vary in number between people not all people have them

Sesamoid bone

small bones warped in tendons where pressure develops, ex. wrist, variable in number, knee caps are sesamoid

Diaphysis

Main shaft of a long bone

Epiphysis

End of bone of a long bone

Metaphysis

in mature long bone where epiphysis meets the diaphysis, in growing bone it contains the epiphyseal plate

Articular cartilage

Thin layer of hyaline cartilage where the bone articulates with another bone

Periosteum

Membrane around the surface of bone not covered by articular cartilage; has two layers

Fibrous layer

(Part of periosteum) made of dense irregular connective tissue, contains blood vessels, lymph vessels and nerves

Inner osteogenic layer

(Part of periosteum) has elastic fibers, blood vessels and various types of bone cells, periosteum necessary for bone growth in diameter, repair, and nutrition, present in all bone types

Medullary

marrow cavity, space in diaphysis filled with yellow bone marrow, present in all bone types

Endosteum

membrane that lines the medullary, contains osteoprogenitor cells and osteoclasts, present in all bone types