bone physiology Flashcards
name the functions of the skeleton
protection
framework
levers
mineral storage
fat storage
blood cell production
what make up bone
collagen fibres
glycosaminoglycans
mineral salts
what is the main crystal salt
calcium phosphate
CaPO4 (hydroxyapatite)
why is collagen in bone
makes bone flexible
what is the purpose of hydroxyapatite in bone (CaPO4)
fills spaces between collagen fibres
gives strength and rigidity
which bone type has the most cancellous bone found
irregular
what is the connnective tissue lining bone
periosteum
what cells develop into osteoblasts
osteogenic cell
what is the function of osteocytes
sense and respond to changes in the extracellular matrix
where are osteocytes found
lacunae (depressions in bone)
how do osteocytes signal
through canaliculi canals
what is the bone cell layer
periosteum
endosteum
haversian canals
what is the function of the bone fluid
transport calcium phosphate into and out of the blood
what do osteoblasts secrete
osteoid (becomes mineralised bone by mixing with CaPO4 crystals)
what enzyme aids in the production of calcium phosphate
alkaline phosphate
how do osetoclasts dissolve the bone
acidify the sub cellular space
enzymatically digest collagen + matrix proteins
describe how osteoblasts are triggered to resorb bone
osteoclasts leave mitogens (growth factors) which cause osteoblasts to mature and lay down new bone
why are osteoclasts needed
removed damaged matrix to avoid incorrect healing of an injury
what is osteopetrosis
too much osteoblast activity
what is osetoporosis
too much osteoclast activity
describe how the bone is vascularised
nurtient artery supplies centre 2/3
periosteal vessels supple outer 1/3
where does ossification start on long bones
middle (diaphysis)
what are young animal bones made of
hyaline cartilage
describe the stages of ossification of long bones
blood vessels grow from the diaphysis into the periosteum
this vascularises and stimulates osteoprogenitor cells to differentiate into osteoblasts.
osteoblasts produce osteoid which leads to the development of the bone collar.
this becomes ossified (CaPO4 crystals form) as alkaline phosphatase is released
matrix is vascularised, osteoblasts and osteoclasts move along the blood vessels for bone remodelling
what are secondary ossification centres in long bones
epiphyseal growth plates
what is appositional growth
allows bone to get thicker
what is endochonreal ossification
how long bones are formed
what is intramembranous ossification
how flat bones form
describe the process of intramembranous ossification
osteogenitors differentiate to osteoblasts in the centre, they secrete osteoid which is mineralised.
periosteum forms and is vascularised.
bone collar forms outwards along the periosteum
what is the difference between intramembrous and endochondral ossification
intramembrous has no cartilage precursor
bone forms between periosteal membranes
