Cellular Function- Cartilage

kms013's version from 2015-09-25 21:51


Question Answer
Functions of carilagefirm consistency of 5 cm allows tissues to beaf weiht w/o permanent distortion 2. forms soft tissue in nose, ears, and throat 3. enables smooth surface, allowing shock absorbing and sliding regions b/w bones 4. guides development in long bones before/after birth 5. avasculature, alymphatic and no nerves
Extracellular matrixhas increased concentration of GAGs and proteoglycans that interact with collagen and elastic fibers; the variations in composition of ECM for 3 types of cartiage that are adapted to local biomechanical needs (aggrecan, hyaluronan) when ECM decreases, so does cartilage; contains type II collagen and aggrecan
What are the characteristics of cartilageECM, Chondrocytes, Lacuane, Perichondrium
chondrocytescells in cartilage embedded in an extensive ECM; syntehsize and maintain ECM components and are located in matrix cavities called lacunae
lacunaematrix cavity/space that contains chondrocytes; functional in mitosis
perichondriumsheath of dense CT that surrounds cartilage in most places, forming an interface b/w the cartilage nad the tissues supported by the cartilage; harbors the cartilage's vascular supply as well as nerves nad lymphatic vessels; articular cartilage covers the surface of bones in movable joints lacks this and is sustained by diffusion of O2 and nutrients from synovial fluid
Hyalin cartilagemost comon of three forms; homogeneous and semitransparent in the fresh state; in adults, found at ends of moveble joints in articular surfaces, walls of larger respiratory passages (nose, larynx, trachea, bronchi), in ventral ends of ribs where they articulate with sternum and in epiphyseal plats of long bones where it makes possible longitudinal bone growth; in enbryo, forms the temporary skeleton that is gradually replaced by bone; most common form, type IIis the principal collagen type; "glassy"---ECM has less collagen but mor proteoglycan around lacunea, changing matrix; osteoporosis is the gradual loss or change in physical properites of HC
type II collagenmost abundant collagen amount found (30% dry weight) occur singly or in smally mitotically derived isogenous groups
articular cartilage zonesresist compression; superficial, middle, deep, tidmark, calcified cartilage
aggrecanthe most abundant proteoglycan of HC
perichondriumexcept in the articular cartilage of joints, all HC is covered by a layer of dense CT; consists largly of collagen type I fibers and fibroblasts
superficial cartilage zoneclosest within joint cavity; fibers go parallel with surface
middle cartilage zone 40-60%; random in distribution; but more perpendicular
deep cartilage zonevery perpendicular, large diameter collagen fibrils
tidemarksplits deep cartilage before calcified cartilage
calcified cartilageboundary between cartilage and bone; example: Chondromalacia--soft cartilage looks like little fragments on bony surface; most common in knee pts have severe pain in knee flexion
fibrocartilagecombination of hyaline cartilage and DCT; IV discs, pubic symphysis; stains differently; connective tissue- structural/blends /w hyaline and bony structure; containing type II collagen and variable amts of type I; also found in attachment of certain ligaments and TMJ; no distinct perichondrium; the chondrocytes line up in isogenous aggregates
meniscus-load bearing (fibrocartilage); protect articular cartilage; outer 10-15% is vascularized...other part gets nutrition via diffusion. This vascularized part is called the "red zone"; layering: fandom fibril layer at surface; lamellar layer orietneed to ward outer layer, inner layer with circum
Elastic cartilagesimilar to hyaline cartilage except contains an abundant network of elastic fibers in addition to collagen type II; usually in small isogenous groups; provides flexible shape and support of soft tissues; cells presnt; chondrocytes and chondroblasts; perichondrium present; found in auricle of ear, the wall of external auditoy canals, the auditory (eustachian) tubes, the epiglottis, and the cunieform cartilage
chondrogenesisall cartilage forms from embryonic emesnchyme in this process: differentiation occurs-- mesnchymal cells are gathered---which retract their extensions multiply rapidly and pack together; when mesochymal cells divide they are called chondroblasts and chondrocytes when proliferation has ceased; they both have rich basophilic cytoplasm rich in RER for collagen synthesis; producting of the ECM encloses the cells in their lacunae and then gradually separates chondroblasts from one another; during embryonic development, the differentiation of cartilage takes place primarily from the center outwar; more central cells= chondrocytes; peripheral cells= chondroblasts; superificial mesenchyme layer = perichondrium; once formed, the cartilage enlarges by interstitial and appositional growth
interstitial growthresults from mitotic division of preexisting chondroblasts
appositional growthinvolves differentiation of new chondroblasts from perichondrium; more important during postnatal development; also important in articular cartilage and epiphyseal plates of long bones to increase length; chondrocytes divide within the matrix
repair of cartilageNOT in young children; damaged cartilage undergoes slow and often incomplete repair primarily by activity of cells in perichondrium which invade the injured area and produce new cartilage; poor quality of repair mainly due to avascularity of the tissue and low metabolic rate = very slow process
_______ is susceptible to calcification during agingHyaline cartilage
Outer annulus fibrosis is what type of cartiage?fibrocartilage (dense regular CT); 30-40 different layers slight like a ligament you can tear
Nucleus pulposustons of proteins (notocord, aggregan, GAGs) that collect fluid so the nucleus pulposus is held together by rings of FC on outside
Microfracture treatmentget rough off; go to bone and force it to bleed; if it bleeds, then it heals with FC instead of scar tissue; works well with small areas of deficit or older population
OATSits your own bone; take plug from non contact area of body; the plug matches your bone so it grows with the destructive area
ACItakes cartiage from another cartilage area; grow in lab; inject chondrocytes into area under flap; post chondral bone does not heal to itself until about 6 weeks

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