bone

bone function

support for body and protection of vital organs periosteum anchors tendons and ligaments fir leverage action, locomotion. concists of cells and type one collagen with the osteoid substance and is vascularized, calcium phosphate in form of hydroxyapatitate christals, residense for marrow, hematopoiesis

macroscopic appearance of bone

compact hard matter, spongy hard matter, pink and blueish, periosteum

periosteum

DICT, covers bine expect at articular surface, united bones by sharpeys fibers, bone vessels and nerves pass to bone

two layers of periosteum

inner cellular layer(fibroblasts/bone lining cells), outer dense, fibrous, vascular

sharpeys fibers

coarse collagenous fibers or bundles of fibers, pass from inner periosteum into periosteal lamellae perforating fibers

how does blood enter into the bone

via canals Volkmann and Haversian canals through the periosteium

long bones arteries and nerves

one or more nutrient arteries at midpoint through branch, nutrient veins retrace artery path, lymph vessels found in canals. sensory nerves in periosteium accompany arterial vessels

compact bone vs spongy (cancellous)

external layer more solid vs internal layer lattice work

all bones contain

some compact and spongy bone with differing degrees of porosity , amount and localization varies with the bones

bone matrix fibers

mostlt type 1 collagen comprises 90% of bone matrix

boone matrix ground substance

proteoglycans, glycosaminoglycans(GAGs), multiadhesive proteins, bone specific growth factors, osteoid

more collagen fibers

tensile strength and the addition of calclium salts is compressional strength. both become mineralized hydroxyapatite.

proteoglycans in ostods

similar to hyaline cartilage, contains hyaluronan (hyaluronic acid), aggrecans* in small amounts Bone specific glyoproteins and proteins present in matrix:

osteonectin

connects collagen and hydroxyapatite

Osteopontin

attaches cells to the matrix

Sialoproteins

cell attachment, involved in mineralization

Osteocalcin

attaches to calcium from circulation, stimulates osteoclast activity (and has other hormone functions

Osteoprogenitors

osteoblast precursors derived from mesenchymal cells during development

osteoblasts

(and “bone-lining cells”) – bone forming,secretes matrix, line growing bone, basophilic

Osteocytes

mature bone cell, an osteoblast that has become surrounded by matrix (in lacunae), maintains matrix homeostasis, less basophilic

Osteoclasts

hematopoietic origin, large, multinucleated, resorb bone - create localized acidic environment and produce digesting enzymes, acidophilic

osteons

consisting of concentric tubular layers (lamellae) parallel to
periosteum & endosteum/bone marrow cavity

haversian canal

in center of osteon

volkmann canals

transverse lamellae canals contain blood vessels and nerves

canaliculi

through lamellae, tunnel through and connect. cellular projections from the osteocytes occupy the canaliculi, communicate through gap junctions

bone decalcified

removal of salts using dilute acids

lamellae

Matrix in a parallel series 3 to 7 m thick,
4 to 20 in a system. Created by an ordered deposition
of matrix. Collagen fiber direction alternates in adjacent lamellae -
maximizes rigidity and strength/ Interstitial lamellae found
between osteons, remnants of old lamellae after remodeling

oval space

in which osteocytes reside between or within lamellae

spongy cancellous bone structure

continuous with compact bone, spongy mass of trabeculae, plates, tubules, fundamentally lamellar, interspaces filled with bone marrow.

bone marrow

Fills cavity of bone, between spaces of spongy bone. Until puberty is hematopoietic =red bone marrow, Later, much replaced by adipose
Inactive fatty marrow = yellow bone marrow, Under stress can reactive

endosteum

covers surface of spongy bone/marrow spaces. delicate layer, one cell thick containing osteoprogenitor cells.