Bone is what kind of tissue? is is avascular?
connective tissue. vascular living tissue
functions of bone tissue are…..
movement and support of body by spine
storage and release of calcium and PO4 ions (homeostatic mechanism, uses when ca lvls too low)
blood cell formation occurs in bone marrow, what is it called
hematopoiesis
what is the composition:
inorganic salts ____%
ground substance_____ %
65-75% (ca hydroxyapaptite)
30-35% (organic part)
-10% proteoglycans and 90% type 1
what are the 2 types of bone
compact (outsides of bones)
cancellous (spongy) trabeculae
lamellar are…
mature bone
parts of bone are:
diaphysis is……
metaphysis is….
epiphysis is…..
main part of bone
growth plate btwn epiphysis and metaphysis (bone that is still growing)
end part
articular cartilage on the end is _____ cartilage for cushioning ends of bone
hyaline
long bone has what 2 types of bone
compact and spongy (trabeculae)
the joint between bones is what kind of cartilage?
in between the cartilage is what?
articular hyaline cartilage
articular cavity
the periosteium is ______ tissue. what does it contain.
immature tissue. it contains immature bone cells that cna repair bone or during development make the mature bone
what is the functional/anatomical unit of bone
osteons-haversian systems
what are osteons ? what do they have in the center?
concentric arrays of lamellae w/ osteocytes (mature cells)
in the center they have the haversian (central) canal that contains vessels, nerve, lymphatic
long bone has what kind of CT?
fibrous ct
volkmann’s canal (perforating canals) run ____ to haversian canals
perpendicular
what volkmann’s canals do to the blood
bring blood horizontally and then run vertially to be the haversian canals
volkmann’s cananls are central canals surrounded by _______ .
what are between them?
lamellae-rings of CT matrix
btwn the lamellae are lacunae for osteocytes
what are in between the rings of lamellae
osteocytes in lacunae
what is the central haversian canal for?
blood supply
what are canaliculi
small canals off of lacuna
what does the canaliculi do?
connects all lacuna and central canal which is bringning in oxygen for the osteocytes
*cancellous bone is not in this arrangement
how many lamella rings can you have in an osteon
up to 8
what are mature differentiated cells in lacunae that synthesize and secrete matrix?
osteocytes
what synthesize and secrete osteoids?
-organic matrix in bone becomes mineralized by endoenzymes
osteoblasts
what cell are multinucleate in the bone and function in reabsorption and bone remodling
osteoclasts
what cells are in the periosteum (outer bone) and endosteum (inner bone) and divide and proliferate
osteoprogenitors
which cells are trapped int heir matrix
osteocytes
osteocyte in lacuna:
- ____ RER
- ____ protein synthesis
- ______ chromatin
- ______ active
little
low
condensed
-not very active cells-shut down once it becomes trapped in its mineral matrix (calcified)
the movement of molecutes from central canal to canaliculi and from one cell to another is through….
gap junctions
osteoblasts:
- ____ and ____ cells
- contains ____ RER and golgi
- on the ____ of developing bone
- what shapeof cells?
- lay down _____ proior to mineralization
- process _____ cells by ____ junctions
- large and basophilic (lots of RER) cells
- a lot of RER and golgi-active protein synthesis
- surface
- cuboid or polygonal
- osteoid
- interconnecting cells by gap junctions
osteoblasts can become what if the matrix becomes mineralized? if this doesn’t happen what can they revert back to?
osteocytes
immature progenitor cells
for osteoblasts, the side facing the bone is very___
active
-highly polarized cells
osteoblasts synthsize and secrete ____ and ____ to mineralize the matrix
osteoids and extoenzymes
what are depresoins for the osteoclats?
howship’s lacunae. cells are sealed in this lacunae to ensure they are remodeling in the correct area
what do osteoclasts use to dissolve mineral matrix with?
what do they use to dissolve organic matrix? what does this respond to?
organic acids
lysosomes -respond to calcitonin (inhibits resorbtion) and parathromone (stimulates resorbtion)
waht does the sealing zone do
what does it have a lot of in the zone?
what are realsed to form hydrochloric acid to break down mineral matrix?
seals active side of cell off from other tissue. prevents acids and enzymes from breaking down tissue beyond it
- has a lot of actin in the zone
- hydroxide ions, chloride ions
where is the active site located in osteoclasts
near edges where they are working on to break down the matrix
why is bone broken down
in reponse to low serum calcium
what is released to stimulate osteoclasts to release enzymes to break down the bone matrix to get calcium out of the matrix
parathormone from parathyroid
what acts to increase surface aresa to secrete more enzymes and acid to breakdown the matrix
ruffled membrane
what stimulates resorbtion ?
what is the opposite of this
parathromone. stimulates activity of osteoclasts and increase blood calcium in parathyroid gland
- calcitonin is the opposite => decrease blood ca if the levels are too high in the thyroid gland
what are the 2 types of bone formatoin? where do they occur? which is the main one?
- endochondral (from cartilage matrix in long bones, MAIN)
2. intermembranous (mesencyme to osteoblasts, short and irregular bones during development)
what is the disease that is a dietary deficiency of calcium or vitamin D
rickets
-matrix doesnt mineralize and bone is weak
what is the disease that resorbtion by osteoclasts is greater than deposition by osteoblasts
osteoporosis
-diminishes matrix (both mineral and organic)
what is the calcificatoin of articular cartilage (hyaline)
arthritis
-calcification by invastion of blood vessels and mineralization of hyaline
what is the progessive thickening of bone
paget’s
-excessive bone formation folllwoing a break in bone
bone formation:
- ___ cartilage formed from mesenchyme
- assume shape of ____
- still all cartilage-periochondirum goes into ….
- osteogrogenitors start developing into …. - cartilage ___ and _____
- triggers blood vessel invation - ____ migrate w/ vessels into calcified cartilage, become osteoblasts, deposit osteoid. ____ removes dead chondrocytes
- _____ ossification centers set up
- continued ____ absored, BONE FINALLY PRODUCED FK
- hyaline
- final bone
- periosteum
- osteoblasts - proliferation and calcification
- osteoprogenitors
- osteoclasts - secondary
- calcium
which zone?
contains hyaline cartilage and no proliferation
zone of reserved cartilage
which zone?
condrocytes in columns, divide and synthesize matrix
zone of proliferation
which zone?
cell division stops, enlarge, start matrix calcificatoin
zone of maturation
which zone?
large spaces, movement of osteoblasts. deposit collage type 1
zone of hypertrophy
which zone?
cells die, matrix calcifies, progeneration and capillaries invade lacunae
zone of cartliage degeneration
which zone?
osteoblasts form from progenitors
osteogenic zone