Term
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Definition
| tissue that is comprised of highly organized ECM |
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Term
| what does firm consistency of cartilage allow it to do? |
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Definition
| bear mechanical stress without distortion |
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Term
| where is cartilage found? |
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Definition
| lining joints, tendons and ligaments, airway (nose, larynx, trachea, bronchus) |
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Term
| functions of cartilage (4) |
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Definition
1. support airways, ligaments
2. shock absorption of joint surfaces
3. smooth movement of joint surfaces
4. bone growth |
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Term
| what is cartilage matrix made up of? (3 things) |
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Definition
1. glycosaminoglycans and proteoglycans (50%)--made up of hyaluronic acid and chondroitin sulfate
3. glycoproteins (5-10%)
4. collagen (type II) (40%) |
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Term
| staining of cartilage matrix |
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Definition
| light--hard to discern because it is in much smaller fibrils than other tissues |
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Term
| EM striations of collagen are masked by interactions with what? |
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Definition
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Term
| very long hyaluronic acid molecules run parallel to what two things? |
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Definition
| collagen fibers and proteoglycans (arranged perpendicular to collagen fibril fiber bound directly to it) |
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Term
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Definition
| dense regular CT covering of cartilage |
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Term
| what is perichondrium comprised of? |
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Definition
| type I collagen and fibroblast-like cells |
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Term
| what does perichondrium do for cartilage? |
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Definition
| since it is highly vascularized, it provides nutritional support for cartilage b/c cartilage does not have blood vessels within it |
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Term
| cells of cartilage (3 types) |
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Definition
-mesenchymal precursor (fibroblast-like) cells
-chondroblasts
-chondrocytes |
|
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Term
| mesenchymal precursor cells |
|
Definition
-fibroblast-like
-found in perichondrium
-differentiates into chondroblasts |
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Term
|
Definition
-in inner surface of perichondrium
-secretes matrix
-H&E basophilic cytoplams, euchromatic nucleus
-differentiates into chondrocytes |
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Term
|
Definition
-within cartilage
-secrete smaller amounts of matrix, maintain cartilage
-represent terminal differentiated cell in this lineage |
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Term
|
Definition
| nest where chondrocytes are trapped |
|
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Term
| two types of growth in cartilage |
|
Definition
1. interstitial growth
2. appositional growth |
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Term
|
Definition
| cell division of chondrocytes in lacunae |
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Term
|
Definition
| differentiation of cells from the perichondrium (much more important type of growth) |
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Term
|
Definition
1. hyaline
2. fibrocartilage
3. elastic |
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Term
|
Definition
-found in airways, at ends of bones at joints, growth plate
-smooth appearing matrix
-cells present in rounded lacunae typically surrounded by more intensely stained matrix
-has a perichondrium |
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Term
|
Definition
-found in tendons and ligaments, intervertebral disks
-cartilage alternating with thick layers of dense type I collagen
-chondrocytes often found in rows
-no perichondrium |
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Term
|
Definition
-found in eustachian tubes, larynx, epiglottis, pinnae of ear
-has abundant elastic fibers in cartilage matrix
-visualized with typical elastin fiber stains
-cells in rounded lacunae
-has a perichondrium |
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Term
|
Definition
| specialized form of CT, comprised mainly of calcified ECM |
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Term
|
Definition
-mechanical support
-locomotion
-metabolic reservoir of minerals (calcium) |
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Term
| what is the ECM component of bone |
|
Definition
|
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Term
|
Definition
-represents 50% of dry weight of bone
-produces lightweight, stress-resistant scaffold of bone |
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Term
|
Definition
-type I collagen fibers
-proteoglycans
-glycoproteins |
|
|
Term
| what is the mineral component of bone? |
|
Definition
| -crystals of hydroxyapatite Ca10(PO4)6(OH)2 |
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|
Term
| what produces the hardness of bone? |
|
Definition
| crystals of hydroxyapatite |
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|
Term
| what is the mineralization process of bone |
|
Definition
| -bone cells do a number of things that lead to increased concentration of calcium and phosphate in the environment leads to precipitation or crystallization of hydroxyapatite |
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Term
| gross anatomy types of bone (3) |
|
Definition
-long bone
-compact bone
-cancellous trabecular, spongy bone |
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Term
|
Definition
-found on outside of bones
-appearing intact, solid |
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Term
| cancellous trabecular, spongy bone |
|
Definition
| -spicules found in the middle of bones |
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Term
|
Definition
| primarily cancellous bone with a thin layer of compact bone |
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Term
|
Definition
|
|
Term
| medullary cavity/marrow cavity |
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Definition
| -where precursors to blood and mesenchymal cells formed, filled with fat in adults |
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Term
|
Definition
|
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Term
|
Definition
|
|
Term
| histologic types of bone (2) |
|
Definition
1. primary bone (woven bone)
2.secondary bone (lamellar bone) |
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Term
| primary bone (woven bone) |
|
Definition
-first bone to appear in embryonic tissue
-remodeled to secondary bone (very little present in adults)
-randomly distributed collagen fibers
-lower mineral content
-high number of cells |
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|
Term
| secondary bone (lamellar bone) |
|
Definition
-term comes form microscopic appearance of ground sections that show concentric layers of material
-haversian system or osteon: structural unit upon which lamellar bone is based |
|
|
Term
| haversian system or osteon |
|
Definition
structural unit upon which lamellar bone is based
-composed of: haversian canal, lamellae, cancliculi, volkman's canals, interstitial lamellae |
|
|
Term
| haversian (central) canal |
|
Definition
-in middle of osteon
-has blood vessels and nerves, lymphatics |
|
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Term
|
Definition
layers of bone with cells/osteocytes in lacunae
-multiple lamellae with collagen fibers at right angles to one another |
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Term
|
Definition
-small pores that connect cells in the lamellae.
-processes of osteocytes found inside here |
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Term
|
Definition
-oblique canals without surrounding lamella
-permit Haversian system to communicate with other systems and the bone marrow |
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Term
|
Definition
| -in between partially remodeled Haversian systems |
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Term
|
Definition
1. osteoprogenitor cells
2. osteoblasts
3. osteocytes
4. osteoclasts |
|
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Term
|
Definition
-mesenchymal progenitor cells derived from bone marrow (can be similar in appearance to fibroblasts, but can also line internal surfaces of bone with appearance of squamous epithelium)
-found primarily in periosteum and endosteum
-differentiate into osteoblasts
-plays key role in bone growth w/in periosteum: appositional growth |
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Term
|
Definition
-secrete matrix that becomes bone
-H&E basophilic cytoplasm bone matrix-synthesizing cell found only on surface of bone
-EM abundant ER
-found in rows, have appearance of epithelium
-differentiate into osteocytes |
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Term
|
Definition
-responsible for maintenance of mineralized bone
-it is an osteoblast trapped inside a lacuna w/in bone
-relatively inactive, but required for bone to be maintained
-transduces signals in response to mechanical strain
-H&E-condensed nucleus weaker staining cytoplasm EM-less ER and Golgi
-connected to other osteocytes and ultimately blood supply by thin dendrite-like cytoplasmic processes that extend through the canaliculi
-at contact site, two cells are gap junctions
-this is terminally differentiated cell in the lineage |
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Term
|
Definition
-degrades bone matrix, responsible for bone resorption
-derived from macrophages, fusion of several cells
-H&E-large multinucleated cells found along bone surface
-EM: cytoplams of osteoclasts are full of vesicles-Golgi, secretory vesicles, 1 degree lysosomes |
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Term
|
Definition
| depressions of bone where osteoclasts are found |
|
|
Term
| structure/function of osteoclasts |
|
Definition
-at margins, tightly adhered to bone matrix
-will produce a ruffled border where acid and lysosomal enzymes (collagneases) are secreted to breakdown the mineralized and organic portions of the bone respectively |
|
|
Term
| remodeling of bone (bone turnover) |
|
Definition
-10% of bone is destroyed and replaced in 1 year in adults
-based on paracrine signaling relationship b/t osteoclasts and osteoblasts
-osteoblasts produce factors that recruit, stimulate, proliferate, and activate osteoclasts
-remodeling liberates bound growth factors
-factors lead to proliferation of osteoprogenitor cells, differentiation of these to osteoblasts, increased synthesis of matrix by osteoblasts
-balanced system where bone destruction stimulates bone formation |
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Term
|
Definition
| disease of decreased bone density that affects the entire skeleton |
|
|
Term
| in whom is osteoporosis most commonly found? |
|
Definition
|
|
Term
| what does decreased bone density lead to? |
|
Definition
|
|
Term
| why is osteoporosis common in post-menopausal females? |
|
Definition
| reduced levels of estrogen, which controls the factors that stimulate production and activation of osteoclasts. also stimulates apoptosis of osteoclasts. also may be needed for cells to become osteoblasts. |
|
|
Term
| what does osteoporosis mean in terms of bone density? |
|
Definition
| amount of mineralized bone reduced within the skeleton |
|
|
Term
| how does estrogen affect osteoblasts? |
|
Definition
| it inhibits the production of cytokines and growth factors that recruit and activate osteoclasts |
|
|
Term
| how does estrogen affect osteoclasts? |
|
Definition
|
|
Term
| how does lack of estrogen affect the process of bone remodeling? |
|
Definition
| more cytokines and growth factors are produced by teh osteoblasts, which leads to more long-living osteoclasts that in turn leads to more bone destruction that is not balanced by high rates of bone formation |
|
|
Term
| what would be an ideal treatment for osteoporosis, what is the limitation of that treatment? |
|
Definition
| estrogen replacement therapy, leads to breast cancer |
|
|
Term
| what kind of growth do osteoprogenitor cells play a key role in? |
|
Definition
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