Flashcards in Bone Tissue Deck (35)
cartilage and bone are both what kinds of tissue?
is bone vascular or avascular?
what are some major functions of the bone?
structure of body, storage and release of calcium and phosphate ions and blood cell formation (hematopoiesis).
What is bone composed of?
inorganic salts (65-70%, main component): Calcium hydroxyapatite.
ground substance (30-35%) organic component: PG and type 1 collagen (which makes up 90% of GS).
What are two types of bone?
1. lamellar: mature bone, it is compact outside of bones and cancellous or spongy trabeculae inside the bones, forms a meshwork.
2. Woven: only in fetus and during bone repair.
Define epiphysis, metaphysis and diaphysis
epiphysis: end part of long bone
metaphysis: growing part of long bone located between epiphysis and diaphysis
diaphysis: shaft or central part of long bone.
what layer in bone is similar to the perichondrium found in cartilage?
periosteum, immature cells are also found here just like in cartilage but now are called osetoblasts.
What is the formation of compact bone?
organized into osteons or haversian systems
What is the mature cell type in bone?
connective tissue is attached to bone by what kind of fibres?
Haversian canal or central canal runs in what direction? and is located where?
runs in vertical direction and runs up through center of osteon in compact bone.
What are volkmanns canals? which way do they run?
they run perpendicular (90 degrees) to haversian canals.
what are the layers called that surround the osteons? what is between these layers? these cells are embedded in what?
lacunae (same as chondrocytes)
tiny lines radiating from ostecytes between layers of lamallae are? what do they carry?
canniculi (which also join to central canal).
O2, nutrients and waste NO blood.
what is the formation of spongy bone?
NO osteons, osteocytes are dispersed throughout the matrix.
what is the main type of collagen in bone?
osteocytes are mature or immature? located in which type of bone?
mature (in lacunae) located in both spongy/compact. synthesize and secrete matrix. have long cytoplasmic processes in cannaliculi. trapped in matrix until they die.
function of osteoblasts?
synthesize/secrete osteoid (organic matrix becomes mineralized). can mature to osteocytes (would then be trapped in matrix for life) or go back to osteoprogenitors.
function of osteoclasts?
multinucleate, involved in resorption and remodeling (breaksdown bone).
What are osteoprogenitors?
in periosteum, divide and proliferate.
do osteocytes have high active protein synthesis?
NO, therefore little RER, condensed chromatin. once mature not alot of synthesis occurs.
cytoplasmic processes from different osteocytes can touch and have what type of junction?
GAP, can pass nutrients, O2, etc.
are osteoblasts highly active?
YES, therefore lots of RER, high protein synthesis, lots of euchromatin. on surface of developing bone, cuboidal.
which enzyme is used by osteoblasts to lay down mineralized matrix?
What is the organic part of bone? the matrix where osteocytes are located have what type of matrix?
periosteum= made up of collagen type 1+PGs
mineralized (has calcium, mature tissue).
as the organic component matures, it becomes mineralized.
osteoblasts are what kind of cell type?
polarized. active face faces maturing tissue (mineralized matrix)
osteoblasts synthesize what cell type?
What kind of enzyme is alkaline phosphatase?
ecto enzyme, sits on PM and mineralizes matrix.
osteoblasts lay down bone in what direction?
growing outward into mineralized matrix
osteoclasts breakdown bone for what purpose? it responds to calcitonin by doing what? responds to parahormone by doing what?
in response to low Ca, it releases Ca from bone.
inhibiting resorption (decreases osteoclasts activity, decreases blood Ca, hormone in thyroid gland)
stimulating resorption (stimulates activity of osteoclasts, increases blood calcium, hormone in parathyroid gland).
osteoclasts sit in what type of lacunae? and have what kind of unique membrane? and what unique zones?
ruffled membrane and has sealing zones to prevent destroying of other tissues.
what protein helps form the sealing zone?
actin filament, interacts with integrin to seal off space and makes sealing zone.
How does bone resorption occur?
lysosomes from golgi release enzymes and H+ which increases acidification causing breakdown of calcium phosphate, products are then taken up by cell and taken to the blood.
Howships lacunae also called?
clear zone (rich in actin, no organelles).