Summary Bone Tissue

Bone Tissue
 Narrow passageways through
the lamellae called canaliculi
connect lacuna where
Useful Termes:
osteocytes lie
 Chondro (cartilage)  Osteocytes are in contact
 Chondrocyte with neighboring osteocytes
 Endochondral through cytoplasmic
 Perichondral extensions and gap junctions
 Osteo (bone)  Nutrients and waste can be
 Osteogenesis exchanged with osteocytes
 Osteocytes either by gap junctions or via
 Periosteum interstitial fluid
 Blast (precursor cell /  Function: support; protection;
the one that produces movement
something)
Spongy Bone
 Osteoblasts
 Cyte (cell)  Spongy (or cancellous) bone
 osteocyte is found where bones are not
heavily stressed or if stress
come from many directions
 No osteons – lamellae
BONE STRUCTURE arranged in irregular lattice of
Compact Bone columns
 Trabeculae: interconnecting
 Denser material rods or plates of bone
 Used to create much of the  Makes bone strong
hard structure of skeleton but light
 Osteon (circular units of  Spaces filled with
bone material and blood marrow – red marrow
vessels) is the basic responsible for red
functional unit of compact blood cell formation
bone (may also contain
 Osteocytes are arranged in yellow marrow – store
concentric layers around a of adipose tissue as
central (Harvison) canal energy reserve)
 Harvision canal run parallel  Covered with
to bone surface and contain endosteum
blood vessels
 Perforating canals run
perpendicular to the surface
and contain blood vessels
 Lamellae of each osteon
form a series of concentric
cylinders around the central
canal

,  Oriented along stress Mechanical Stress and Bone
lines Strength
Bone Matrix  Stress causes bone
remodeling to:
 Mixture of organic and
 Increase bone mass
inorganic components
(density)
 Organic component
 Align trabeculae with
 35% extracellular
stress
protein fibres
 Changes causes by:
(collagen) and
 Osteoblasts activity
proteoglycans
(increases with stress)
 Contributes to bone
flexibility – high BONE CELLS
tensile strength
 Osteoprogenitor
(resistance to be
(osteogenic) cells are stem
pulled apart)
cells which maintain the
 Inorganic component
population of osteoblasts
 65% mineral crystal:
 Osteoblasts produce bone
calcium hydroxide to
matrix (a process called
make hydroxyapatite
ossification)
crystals
 Osteocytes are mature bone
 Hard and brittle –
cells – exchange nutrients
high compressive
with blood
(weight bearing)
 Osteoclasts release acid
strength
and enzymes to digest
 Water
mineral component of bone
Collagen matrix – resorption
 Most abundant protein in the Osteoblasts
human body
 Formation of bone through
 Found in bones, muscle, skin
ossification or osteogenesis
and tendons
 Collagen is produced by ER
 Substance that holds the
and Golgi and is release by
body together
exocytosis
Blood and Nerve Supply  Precursors of hydroxyapatite
stored in vesicles, then
 Bone is richly supplied with
released by exocytosis
blood
 Ossification



Osseus tissue is a type of
Connective Tissue



 Nerves accompany the blood  formation of bone by
vessels that supply bone osteoblasts