W3 BONE MATRIX, CALLS AND STRUCTURE

Ground substance (Bone matrix)

• jelly like substance

• aids in exchange of nutrients

• helps with movement for collagen fibres

Collagen fibres (bone matrix)

• contributes tensile strength

• ability ti twist and bend

Calcium phosphate crystals (Bone Matrix)

• provides compressive strength

Osteoprogenitor cells

• stems cells that differentiate into osteoblasts

Osteoblasts

• bone building cells, secrete collage fibres and ground substance

• osteoblast - build

• secretes bone matrix

osteocytes /bone-lining cells

• mature bone cells that maintain the matrix

• inactive osteoblasts

• over see/sight - watching to see what’s going to happen

• there if we need to build up bone again

osteoclasts

• bone resorbing cells, break down matrix and release stored materials

• osteoclasts = clear

Compact bone (bone tissue)

• dence and protective

• compact tissue is arranged into osteons

  • runs parallel to the long axis of a bone (i.e. the shaft)

  • act as tiny weight bearing pillar

components of osteons

• central canal - containing blood vessels and nerves

• concentric circles - hollow cylinders of matric

• osteocytes - lie between the cylinders of matrix

spongy bone (bone tissue)

• lighter and more “adaptive”

• osseous tissue arranges into a irregular lattice of this needle like stuctures called trabecule

  • precisely orientatated to resist forces from all directions and transfer weight without breaking

  • lighter than compact bone

  • in long bones, mainly found in the proximal and distal epiphysis

• bone marrow can be found between gaps

Structure of bone

• outer layer is dense, smooth compact bone

• internal layer of spongy bone

• periosteum - outer connective tissue membrane

  • covers compact bone

  • contains blood vessels and nerves

• endosteum - internal connective tissue membrane

  • covers spongy bone

epiphysis (long bone)

• “epi” means on top

• composed mostly of spongy bone

• red bone marrow stored in the spaces

epiphyseal plates (long bone)

• also called growth plates

• site of new bone growth

• increasing bone length during childhood and adolescence

Diaphysis (long bone)

• “dia” means through

• composed mostly of compact bone

• strength and support

Long bone

Types of bones