Flashcards in Bone & Cartilage Deck (37)
What is the CT that surrounds the outside of compact bone
What is the CT that lines inner surface of bone facing marrow cavity and haversian canals
What are osteoblasts
secrete bone matrix (uncalcified); found only at the boundary bet bone and periosteum/endosteum
What are osteocytes
osteoblasts that have become "trapped" within lacunae of calcified matrix; connected to one another by gap jxns via processes that extend through canaliculi for the transport of nutrients and wastes.
what are osteoclasts
large, blood derived (related to macrophages) multinucleated cells that degrade the bone matrix (secretes H+ and lysosomal enzymes) for reabsorption.
What is bone matrix composed of
Organic: collagen (type 1) GAGs, glycoproteins
Inorganic salts: Calcium phosphate crystals
what are details of immature bone
layed down randomly; forms trabeculae that grow together.
concentric rings of lamellae. With lacunae
Bone is highly vascular:
blood vessels within marrow
blood vessels peripherate in marrow
blood vessels in matrix of bone.
What is the haversian canal
the vessels that run through the center of the osteon
what is volkmanns canal
interconnect the central canal and is a way to get blood vessels bet central canals
what are canaliculi
small canals; connect neighboring lacunae
immature bone has a randomly:
interwoven collagen fiber HAP matrix
Osteoblasts lay down new:
matrix in concentric lamellae
Cartilage is avascular CT T/F
What type of collagen in cartilage
Chondrocytes, unlike osteocytes:
Actively secrete matrix
where does chondroblast exist
between cartilage and CT; differentiate into chondrocytes as soon as they completely get surrounded by matrix.
What dont you see in cartilage
what is the CT associated with cartilage
perichondrium; dense CT; contains fibroblasts and type I collagen. Has blood vessels but dont go into cartilage matrix.
Perichondrium is NOT present in:
articular surfaces and epiphyseal plates
what are chondroblasts derived from. They secrete matrix via ___ growth
progenitor cells in perichondrium; appositional
Chondrocytes secrete matrix via ____growth
interstitial; actively divide
What is hyaluronic acid composed of
a GAG; extremely long that has proteins, smaller GAGs attached via aggregan molecules
What is the cartilage matrix composed of
2. Fibers: hyaline (type II collagen), elastic (type I and elastic fibers), and fibrocartilage (type I and II collagen)
3. Hyaluronic acid
4. Proteoglycans & GAGs: Aggrecan, choidroitin sulfate and keratin sulfate.
The cartilage matrix forms a large molecule with a lot of ____charge which binds cations and water forming hydrated gel that is resistant to compression
What are features of hyaline cartilage
1. homogenous, amourphous matrix
2. "typical" cartilage
3. Not uniformly distributed: capsular, territorial and interterritorial matrix
where is hyaline cartilage found
1. articular surfaces
2. epiphyeal plates
3. costal cartilages
6. fetal skeleton
What are features of elastic cartilage
1. contains elastic fibers
2. found in pinna of ear, ear canal, and epiglottis
what are features of fibrocartilage
1. contains fibroblasts and type 1 collagen fibers. (inc tensile strength)
2. resist compression bc it has hyaluronic acid in its ground substance
3. NO perichondrium
4. Found at symphysis of joints (pubic) and intervertebral discs), and articular discs and menisci.
Type I cartilage is very ___
eosinophilic; so fibrocartilage will appear very pink.
fibrocartilage have ___groups of cells
What is endochondral ossification
bone is formed through the ossification of a cartilagenous model.
what is intermembranous ossification
mesenchyme within CT differentiated directly to osteoblasts which create bone de novo.
what are the zones of endochondral ossification
1. zone of resting cartilage: quiscent cartilage @ end of epiphyseal plate
2. zone of proliferation: chondrocytes actively divide producing columns of isogenous cells.
3. zone of hypertrophy: chondrocytes inc in size and accumulate glycogen
4. zone of calcification: chondrocytes degenerate; HAP crystals form within cartilage.
5. zone of ossification: Osteoblasts synthesize bone over the layer of calcified cartilage.
What are phases of fracture repair
1. Hematoma (blood clot)
2. CT invades hematoma
3. Build precallus (big knot of cartilage in between two pieces of broken bone)
4. Calcification and further ossification creates immature bone = callus
5. Remodeling creates mature bone