To do list for today

• functions of the skeleton• bone shapes• general features of bone – parts• bone histology = cells + matrix• Vitamin D, calcium & bones• structural disorders of bone

• osteoporosis

long short flat irregular

Fig. 6.2a(TE Art)Epiphysis

Epiphysis

Diaphysis

Spongy boneEpiphyseal line

Compact bone

Medullary cavity

Endosteum

Articular cartilage

Periosteum

Articular cartilage

osteo = boneperi = aroundendo = withinartic = joint

Compactbone

SpongyBone(diploe)

Suture

Flat bones

Bone tissue = bone cells = matrix

periosteum

endosteum

osteon

Central canal

trabeculae

Perforating canal

Perforating fibers

Compact boneSpongy boneBone marrow

Osteoprogenitor

** osteocyte **

** Osteoblast **

Bone cells

canaliculi

Stem cells

osteoclast

Bone dissolving macrophages** Osteoclast **

Why dissolve bone??

Paget’s disease (osteitis deformans) = increased osteoclast activity

Bone matrix

• 1/3 organic = flexibility• collagen• protein-carbo complexes

• 2/3 inorganic = strength• calcium phosphate salt• magnesium, sodium, potassium…•Osteogenesis imperfecta = impaired osteoblast function, collagen unorganized, brittle bones

Calcium and vitamin D• need vitamin D to absorb calcium in the small intestine• need UV to make vitamin D• osteomalacia (rickets) = deficient vit D, soft bones

Shell-less chickno calcium, no ossified bone

Bone deposition = resorption

Osteoporosis = porous bones

• decreased deposition• increased resorption• spongy bone affected

• bones become brittle• women > men

• less bone mass• lose it earlier & faster• decrease in estrogen

• build bone mass ???!

Drink milk?What about my latte milk?Does that count?

Things that affect bone resorption or deposition:• corticosteroids – reduce osteoblast activity (matrix synthesis) increase osteoclast activity• estrogen & testosterone – increase osteoblast activity• caffeine – binds Ca so it’s excreted• smoking – decrease osteoblast production, impairs Ca absorption, interferes with ERT

www.pdrhealth.com/

Osteoporosis and Anatomy….

Areas with more spongy bone

kyphosis

Hip fracture complications