Bones Flashcards
components of skeletal system
bone
cartilage
joints
ligament
connective tissue
function of skeletal system
support against gravity
leverage
protection
storage of calcium
blood cell production
types of bone
flat (2 layers of compact bone with dipole in middle)
long (leverage)
short (transfer forces)
irregular (multi purpose)
sutual (bone between skull bones)
sesamoid (small develop in tendons)
long bone features
Diaphysis (shaft) main long part of 2 dense bone layers surround bone cavity
epiphyses (ends) made of spongy / trabecular bone covered in articular cartilage
osteoclast crusher cell
dissolves old bone to be replaced
osteoblast
immature bone cell secreting matrix proteins to become mineralised
osteoid
matrix protein
osteocytes
mature bone cells maintaining matrix by branching through allowing Ca to travel
osteoclasts
multi nucleated cell secreting acid and enzymes to dissolve bone matrix
structure of compact bone
osteon (long cylinder)
central canal (tunnel for blood vessels)
lamellae (concentric layers of matrix)
lacunae
what causes the osteon to be strong
collagen fibres in different directions
features of trabecular bone (sponge)
no ostens
no canal as nutrients can diffuse in
trabeculae (branching network strong in directions)
red and yellow marrow (red=provides nutrients and forms rbc, yellow=stores fat)
bone vs forces
osteons = strength in long axis
trabecular - strength in range of directions as trabeculae align according to direction of loading
periosteum
membrane outside bone
-outer fibrous layer = collagen fibres
endosteum
membrane lining bone
inner cellular layer for metabolism and blood vessels
compact vs trabecular bone - structure
C=osteons, canal, concentric lamellae
T=network of cross bridges
compact vs trabecular bone - location
C=shaft of long bone
T=inside short / flat bone and epiphyses of long
compact vs trabecular bone - blood supply
C=through canal and perforating canal
T=via red bone marrow
ossification
formation / conversion to bone
intramembrane ossification
inside formation of flat bone
endochondrial ossification
bone forming inside cartilage
appositional bone growth
adding more bone to outside increasing width
remodelling of trabecular bone
as forces apply it become denser and compact into compact bone
1st stage of endochondrial ossification
chondrocytes in calcifying matrix enlarge and die
2nd stage of endochondrial ossification
osteoblasts cover shaft in a thin layer of bone
3rd stage of endochondrial ossification
blood vessels and osteoblasts penetrate to form a primary ossification centre
4th stage of endochondrial ossification
primary ossification centre enlarges until meets with collar
5th stage of endochondrial ossification
secondary ossification centre formed at epiphyses forming 3 bones
growth in bone length
3 sections of bone connected by cartilage allows expansion and stopped by hormones and fusion of cartilage
appositional bone growth
bone deposited by osteoblasts outside while inside resorbed by osteoclasts.
bone remodelling
continuous growth and breakdown
osteocytes detect forces and adapt to loading
stage 1 of fracture repair
bleeding and formation of a clot to hold together bone
stage 2 of fracture repair
formation of external callus (cartilage) and internal callus (sponge bone)
stage 3 of fracture repair
external callus replaced by bone, internal unites broken ends
stage 4 of fracture repair
initial swelling remodelled
