Histology of Bone Flashcards
Functions of bone
protection support mechanical basis for movement storage hematopoiesis
Bone classification based on shape
long short flat irregular sesamoid
Long bones
longer than they are wide; upper and lower limbs
Short bones
cubed in shape, carpals and tarsals
Flat bones
plate-like; sternum and ribs
Irregular bones
complex shape; vertebrae and hip bones
Sesamoid bones
formed in tendons, act to alter pull of tendons; patella
Gross observation of bone types
compact
spongy
Structural components of long bones
Diaphysis/shaft
Metaphysis
Epiphysis
Diaphysis
compact bone on outside, Medullary cavity for R or Y marrow
Endosteum
cells belonging to stroma of marrow or derived from osteoblasts, very thin, osteoprogenator cells (osteoblasts), contains osteoclasts too
Periosteum
covers outer surface of bone, vascularized and have osteoprogenator cells
Metaphysis
area between diaphysis and epiphysis
Epiphysis
contains articular surface of Hyaline cartilage
Epiphyseal plate
in growing individuals, Hyaline cartilage activity lengthens long bones
Epiphyseal line
in adults, solidified epiphyseal plate
Perforating/Sharpey’s fibers
fibers that hold periosteum to bone surface with type I collagen
Bone structure of short/flat/irregular/sesamoid
periosteum, compact bone, spongy bone (diploe), endosteum (lines trabeculae with R and Y marrow between)
General composition of bone tissue
Cells
ECM
Cells in bone tissue
osteogenic cells
osteoblasts
osteocytes
osteoclasts
Osteogenic cells
like mesenchymal stem cells
Osteoblasts
synthesize and secrete osteoid, activity signals calcification to occur
Osteocytes
don’t lay matrix, stuck in matrix
Osteoclasts
break down bone, formed by monocytes
ECM in bone tissue
osteoid (organic), type I collagen and bone matrix proteins (GAGs, glycoproteins, osteoclasin (vitamin k dependent polypeptide, helps calcify matrix), osteonectin)
Canaliculi
cytoplasmic extensions from osteocytes in lacunae, how nutrients are provided and waste is removed, connected via gap junctions
Primary bone
also called woven or immature bone, formed during embryologic development or bone repair, contains lots of osteocytes, lower mineral content, temporary
Secondary bone
also called lamellar or mature bone, highly organized, collagen fibers in layers, concentric circles with BVs in center, present in adults
Osteons
also called Haversian systems, Haversian canal (containing n, v, and a), concentric lamellae made of bone ECM (collagen fibers run at 90 degrees from previous lamellae), outer collagen layer is called cement line
Outer circumferential lamellae
lamellae encircling entire diaphysis
Interstitial lamellae
old lamellae of older osteons
Volkmann’s canal
also called perforating canal, connect Haversian canal to other osteon layers
Osteon development
osteoclasts cut through bone to create space for new osteon, inward growing BV fills center of canal that is lines with osteoblasts that begin lying down new bone
Regions of osteon development
cutting cone
reversal zone
closing cone
Lamellar bone of spongy bone
does not contain osteons, trabeculae surrounds red marrow space
