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29 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What is the mineral abundantly found in the ECM of bone?
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hydroxyapatite
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What collagens make up the bone matrix? What is their prevalence in the matrix?
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90% w/v type I collagen
Small amnt type 5 Traces types 2, 11, 13 |
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What is the role of proteoglycans in bones?
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Non-collagenous part of bone, contribute to compressive strength, bind growth factors, and inhibit mineralization.
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Compare and contrast osteonectin and osteopontin.
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Both are glycoproteins in the matrix of bone marrow. Osteonectin attaches collagen fibers to ground substance (hydroxyapatite), while osteopontin mediates attachment of cells to bone matrix.
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What is the role sialoproteins I and II?
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They mediate attachment of cells to bone matrix, and initiation calcium phosphate formation during mineralization.
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What is osteocalcin?
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A bone specific vitamin K dependent protein. It pulls ca++ from the blood, attracts and stimulates osteoclasts in bone remodeling
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What are the 2 layers of the periosteum? What are they made of?
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1. Outer fibrous layer
2. Inner cellular layer |
1. Dense connective tissue. Some of the collagen fibers become embedded in the bone (Sharpey's fibers), anchoring tissue to bone.
2. Osteoprogenitor cells. Reduced in bones not growing. |
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Describe the endosteum.
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The endosteum lines the interior surface of the bone. It consists of osteoprogenitor cells, osteoblasts, and bone-lining cells.
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What is the difference between red and yellow marrow?
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Red marrow contains developing blood cells, blood vessels, and reticular cells and fibers. Yellow marrow contains fat cells.
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What happens to red marrow as we age?
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It is replaced by yellow marrow. Persists only in the sternum and iliac crest. Can reappear due to rapid blood loss.
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Describe an osteon.
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Osteons are the cylindrical units of mature compact bone. Have layers of lamellae surrounding the haversian canal, which contains vessels and nerves.
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Canaliculi of haversian systems are arranged in a radial pattern and do not open into the osteonic canal. (T/F)
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False. They ARE arranged in a radial pattern, but DO open into the osteonic canal.
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How do nutrients enter the bone?
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Vessels enter through a nutrient foramina in the epiphises and diaphyses.
Metaphyseal vessels enter at the metaphyseal region. |
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How are collagen fibers in adjacent lamellae arranged to each other?
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They are perpendicular, allowing for greater strength.
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What the heck is a Volkmann's canal?
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A canal perpendicular to the long axis of a bone connecting to Haversian canals.
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How is blood distributed throughout the bone?
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Centrifugally. Blood enters the marrow cavity and leaves through the periosteum.
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What is the one area of the bone with lymphatic drainage?
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The periosteum. Veinous drainage also happens here.
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Contrast mature and immature bone tissue.
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In terms of immature bone:
Lamellar pattern: no Greater cell density Cells randomly arr. Greater ground substance less heavily mineralized forms more quickly |
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What is core binding factor alpha 1 (CBFA1)
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Bind to mesenchymal cells to produce osteoprogenitor cells.
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Distinguish between osteocalcin, osteonectin, osteopontin.
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Osteocalcin pulls calcium from the blood, attracts and stimulates osteoclasts.
Osteonectin: attaches collage fibers to hydroxyapatite Osteopontin: mediates attachment of cells to bone matrix |
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What would be the appropriate stain for an osteoblast? What would the cell look like under the stain?
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The PAS stain (stains carb macromolecules). Proteoglycans are abundant in these cells.
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Prominent clear Golgi area, abundant ER and free ribosomes. Alkaline phosphatase reaction at cell membrane.
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How to osteoblasts communicate with each other and other osteocytes?
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Via gap junctions.
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What are the 3 formative states for an osteoclast? Compare/Contrast the 2 active states.
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1. quiescence
2. formative 3. resorptive |
Formative and Resorptive both evidence by more rER, well developed Golgi. The resorptive will show in increase in lysosomes. Formative may have some osteoid.
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What is the clear zone of osteoclasts comprised of?
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Actin filaments, and the binding proteins talin and vinculin.
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What characterizes the clear zone of osteoclasts?
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Heavily folded plasma membrane, close proximity to mitochondria and lysosomes; many proton pumps.
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How to osteoclasts decalcify the matrix?
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By acidification. Carbonic anhydrase II converts H20 and CO2 to carbonic acid, which then ionizes. H+ ions are then pumped thru ATP-dependent pumps in the ruffled border.
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What 2 hormones are used in osteocyte regulation, and what are their functions?
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PTH: from parathyroid, stimulates osteocyte activity.
Calcitonin: From thyroid, inhibits osteoclasts activity. |
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What must occur in order for calcification to occur?
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Concentrations of Ca++ and PO4- must exceed threshold levels. Sialoproteins and osteocalcin bind extracell Ca++, increasing local concentration.
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What is the first step in endochondral ossification?
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Mesenchymal cells differentiate into chondrocytes (collagen type II producing cells), which begin secreting cartilage matrix.
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