bone structure unit 4

How much bones are in the body?

206

bones main function

protect

support

levers

storage Calcium and phosporus

produce blood cells

bone composition

bone cells - osterocytes

inorganic salt

collagen

marrow

long bone epiphysis

ends of bones

Function of epiphysis

articulates w another bone

en ds of epiphysis coated w what

cartilage

shaft of bone

diaphysis

where is the periosteum

around the bone

endosteum

inner lining of bone

medullary cavity

yellow marrow filled cavity

yellow marrow

stores fat

red marrow

produces blood cells

Where is spongy bone found?

epiphysis

compact bone

tightly packed tissue under the periosteum wall

haversian canals

allow the passage of blood vessels for oxygen and nutrients

osteons

structural unit of compact bone

osteocytes

mature bone cells

Perforating (Volkmann's) canals

like Haversian canals but connects horizontally

lacunae

small cavities in bone that contain osteocytes

canaliculi

little channels that connect lacunae

osteogenesis

formation of bone

osteocytes function

maintain bone structure by recycling Ca+ salts

help w repairs

connect passing nutrients

osteoclasts resorption (osteolysis)

Control the amount of bone tissue

acid/enzymes to dissolve the bony matrix

Release stored minerals (ca+2 and Po4 -3) to blood stream when needed

osteoblasts

bone making

Lays down new bone matrix

promote Ca +2 deposition in bone matrix

turns into osteocytes when surrounded by bone matrix

bone matrix

ground substance that calcium becomes part of

turns into a hard substance

Intramembranous Ossification

formation of flat bones

where does intramembranous ossification comes from

embryonic or fetal fibrous connective tissue

steps of intramembranous ossification

1. stem cells gather (ossification center) and become osteoblasts

2. Osteoblasts get trapped in matrix -> calcified osteocytes (mature)

3. Trabeculae (holes form first) form spongy bone

4. periosteum develops - tough outer coating

endochondral ossification

forming long bones

cartilage -> bone

endochondral ossification steps

1. Bone collar forms around the diaphysis of the hyaline cartilage model.

2. Cartilage calcifies in the center of the diaphysis

3. blood vessels enter cartilage

4. osteoclasts break down spongy bone to make marrow cavity

5. epiphyses begins to calcify

articular cartilage

cartilage surrounding epiphyses top part

epiphyseal plate

cartilage between epiphysis and diaphysis

stops growth after puberty