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88 Cards in this Set
- Front
- Back
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What is cartilage?
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Specialized CT with firm consistency and lacks vascularity.
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What are chondrocytes?
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Connective tissue cells.
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Where are cells in cartilage?
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Cells are embedded in ECM and live in a lacuna (lake)- a more soluble area in the ECM.
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Describe cartilage ECM.
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Made of Type II collagen. Ground substance with GAGs, proteoglycans, and adhesion proteins (chondroitin sulfate, hyaluronic acid, chondronectin). Has high water content.
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Where do you find cartilage?
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External part of ear, nose, epiglottis, IVD, trachea, bronchi. Resists deformation by mechanical forces to protect from shock.
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What is articular cartilage?
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It is smooth and reduces friction.
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Which cells produce cartilage?
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Chondrocytes.
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What do you look for in a cartilage slide?
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Looks watery, with little lakes of different size. Typically some sortof boundary layer called perichondrium.
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What is hyaline cartilage?
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Found at end of bones, type II fibers, most common in body, stiffens structures.
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Where are hyaline cartilages
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Major airways, synovial joints, articular surfaces.
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Describe elastic cartilage.
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Type II collagen, with dark staining areas. Flexible to deformation, epiglottis, external ears.
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Describe Fibrocartilage.
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INtermediate type of tissue between dense CT and hyaline cartilage. Has lots of collagen. Always associated with Dense CT. Cells are in lacuna (notice these so you don't confuse it with dense irr. CT). Some flexibility, yet strong, made with Type I collagen.
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What are IVDs and pubis symphsis made with?
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Fibrocartilage
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How is cartilage organized?
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Surrounding cell layer (perichondrium). This blends into surrounding loose CT. Perichondrium has progenitor cells that give rise to chondrocytes.
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What is exception to rule that all spaces are lined with Epithelium?
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Where bone meets bone.
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High or low metabolic rate in cartilage?
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Low, because lack of vascularization.
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How does cartilage grow?
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2 ways. 1) Cartilage cells are generated by chondroblasts. Appositional growth, from the periphery. 2) interstitial- from the inside- coming from chondrocyte division (common in long bone growth)
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What is chondroblast?
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Forms chondrocytes.
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Why does articular cartilage have only interstitial growth?
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find answer
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Describe bone.
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Bone is a dynamic living tissue with contiuosly responding to stresses. New bone is deposited and old bone is absorbed.
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What is remodeling?
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Bone cell turnover is at a rate of 10% per year.
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Which type of cartilage growth dominates in early life? Later life?
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Both in early growth, appositional dominates later.
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What are the functions of bone?
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support, protection, levers for muscle action, reservoir for calcium/phosphorous ions, space for blood cell production.
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What are 2 components of bone ECM
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organic ECM- called osteoid. Gel like ECM with collagen, gags and proteins. inorganic matrix- hydroxyapetite. Putting down calcium phosphate in crystalline structure. Can also be digested to provide calcium and phosphorous to blood.
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What are osteoblasts?
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Osteoblasts create bone (osteocytes).
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What is an osteoclast?
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Break down bone predominantly by breaking down hydroxyapatite.
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What are 3 bone cell types?
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osteoblasts, osteocytes, osteoclasts.
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Where do osteoclasts originate and what are they related to?
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Originate in blood and are related to macrophages.
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What is ECM responsible for?
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hardness of bone and limited flexibility.
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What is bone composition?
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ECM, Organic and Inorganic parts as follows: 1) calcified ECM and cells living within lacuna. Surrounded by periosteum, endosteum 2)Organic- fibers, GAGs, proteoglycans, proteins, collagen I, adhesion proteins, etc, 3) calcified ground substance.
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What are 2 main types of bone?
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compact and spongy
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Describe compact bone.
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Dense, closely arranged layers or lamellae of bone without spaces.
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Describe spongy bone.
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Cancellous or trabecular spicules of bone that act as struts within the interior of the bone.
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How do you prepare bone slides?
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Grind it down and thin slice.
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What does bone slice look like?
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Center with bone marrow
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What are microscopic types of bone?
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Found in either spongy or compact bone. Primary and Secondary.
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Describe Primary bone.
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Non layers, no particular structure. Low mineral content, lots of osteocytes, irregular collagen bundles. Mostly in fetus and in repair. Also in tendon insertion and alveoli of teeth.
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Describe Secondary bone.
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Mature of lamellar. High mineral content, parallel collagen arrangement, with parallel or concentric rings of bone.
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What are embryionic, mesenchymal stem cells of bone?
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osteoprogenitor cells that becomes osteoblasts to become osteocytes.
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What do osteoblasts do and where are they seen?
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Osteogenic cells that secrete bone matrix. You'll see on endosteum as cuboidal to columnar on bone surface. Take up Ca and Ph from blood and make collagen to form calcified matrix.
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Describe Osteocytes.
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Former osteoblasts trapped w/in lacuna. Conform to shape and size of lacuna. Surrounded by uncalcified matrix (osteoid).
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What are canaliculi and where are they seen?
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Connect adjacent lacuna for osteocyte communication and transportation of nutrients, hormones and waste. Little holes in bone (little canals).
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Which bone cells originate in blood forming tissue.
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Osteoclasts are derived from macrophages; digest bone matrix during remodeling, repair or resporption. Multinucleated, acidophilic, motile. Reside in digested depression on bone surface.
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What causes bone loss in women?
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Low estrogen and lack of exercise early on.
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What is a Howship's Lacuna?
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Site of osteoclast activity. Seen as cell sitting in a depression.
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Describe Periosteum
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Dense CT, lines the outside of most bones. outer layer is vascularized. Inner cellular layer made of osteoprogrenitor cells and osteoblasts.
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What are sharpey's (periosteal) fibers?
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Fibers that connect bone to periosteum.
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Describe Endosteum.
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Lines central cavity of bones (spongy bone). Composed of osteoprogenitor cells, osteoblasts and osteoclasts.
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What are circumferential laminae?
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find answer
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How is mature bone organized?
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In dense bone, blood vessels act as organizers. Diffusion thru matrix is poor. Osteoblasts make layers and become osteocytes in lacunae. New osteoblasts are recruited and process repeated and you get concentric rings (Haversian system). Lamallae are laid down from outside in.
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Describe Haversian Canal
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Contains blood vessel, nerves, loose CT, and endosteum. Looks like concentric rings.
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What are volkmans canals?
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blood vessels b/w osteons
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How do we make bone?
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Mesenchyme in embryo organizes itself in a sheet in embryo. Cells then condense and differentiate into osteoblasts and start making bone. Bone starts at a loci and grows readially within a flat structure. Later, bone is remodeled to become 2 plates with marrow cavity
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What is diploe?
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Spongy bone between compact bone sheets.
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What is 2nd kind of bone formation?
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Endochondral ossification. Bone from cartilage. Begins with membranous bone formation along the collar of the cartilage bone model. Collar is invaded by blood vessels that bring in blood and mesenchyme (that becomes osteoblasts). Then alteration of hylaine cartilage at the site of vascularizationa
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Describe bone formation at the epiphyseal plate.
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Resting zone, proliefration zone, hypertrophy zone, calcification zone, ossification zone
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What is epiphysis?
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top and bottom of bone. Loss of epiphysal plate stops bone lengthening.
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What do you see at Resting zone
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densely packed lacunae
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What do you see at zone proliferation
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cell growth
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What do you see at hypertrophy zone?
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cells size enlarging
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What do you see at calcification zone
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You see osteum, blood and calcium- starts to get darker.
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What do you see at ossification zone?
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Bone, more blood, see periosteum continuous peri
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what do you see in bone marrow?
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wide capillaries with blood, osteocytes, etc.
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What is role of growth hormone
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made by pituitary, goes to liver this stimulates cartilage which becomes bone.
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What if too much growth hormone?
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Makes too much bone growth and become giants.
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After epiphysis is closed what happens if they still have growth hormone?
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Bones in face widen and are irregular.
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What is pituitary dwarfism?
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Regular head, very short long bones- not enough growth hormone produced.
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What happens in Vitamin C deficiency
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Scurvy. Impairs collagen and osteoid secretion. Collagen breaks down without Vit C and internal organs are basically melted away.
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What happens in Vitamin D of Calcium deficiency
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Rickets- bones are soft, get bent legs. In adults osteolasia
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What is osteoporosis?
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Bone resporption is less than bone break down.
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What is osteopetrosis?
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Impaired osteoclast function. Failure to remodel bone properly. Loss of normal marrow compartment.
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How are cellular processes within canaliculi connected? Why?
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Osteocytes in canliculi are connected via gap junctions for communication.
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How is diffusion accomplished in bone?
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Through small channels called canaliculi.
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What is another name for osteon and what is it?
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Haversion system- neurovascular canals around a central channel of blood vessels that comprise a system of lamellae
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What is the relationship between Haversion canals and Volkman's canals.
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Volkman's canals pierce columns of neurovascular bundles at right angles to Haversion canals.
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Give examples of flat bone.
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skull, jaw, clavicle
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How is flat bone made?
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Mesenchymal cells condense and differentiate into osteoblasts and then osteocyte as bone is deposited. Radial growth. Then bone is remodeled to have 2 sheets of compact bone with spongy bone between.
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How are short and long bones formed?
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A cartilagenous model of bone forms from condensed mesenchyme with both appositional and interstitial growth. Primary ossification begins with membranous bone formation along the collar of cartilage. Collar is then invaded by blood vessels bearing osteoclasts and mesenchyme that become osteoblasts. Last hyaline cartilage is altered.
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Describe alteration of hyaline cartilage as the last step in long bone formation.
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Chondrocytes- hypertrophy,
Matrix mineralizes, chondrocytes die, osteoblast deposits osteoid, replacing mineralized cartilage. |
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Describe long bone growth.
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Lengthening of bone at epiphyseal plate, ossification of cartilage trail, increase diameter from coordinated deposition of bone on outer surface. At maturity, cartilage growth stops at epiphyseal plate. It becomes ossified and separation b/w primary and secondary is obliterated.
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Describe Hormonal regulation of epiphyseal plate growth.
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Anterior pituitary produces Growth Hormone. Liver reposnds to GH and makes Insulin like growth factor (IGF). IGF stimulates cartilage and bone growth.
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What controls the activity of serum calcium levels?
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PTH responds to low calcium levels and the calcitonin from thyroid inhibits osteoclasts to reduce blood Ca levels.
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What is articular cartilage?
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Areas where 2 surfaces touch each other like bone to bone, bone to cartilage, etc.
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What is synovial fluid?
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lubrication in areas of extensive bone upon bone surfaces.
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What is periosteum?
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Dense CT; lines the outside of most bones; outer layer is vacularized
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What is endosteum?
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Lines the central cavity of bones (spongy bone); composed of osteoprogenitor cells osteoblasts, and osteoclasts.
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What is perichondrium?
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thin layer of CT cells surrounding cartilage.
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What is the annulus fibrosis? Nucleus pulposus?
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In IVD,outer layer of dense connective tissue called fibrocartilage and the inner portion is the nucleus pulposus, a type II collagen.
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