The most amazing story of bone histology Dr Duran Kala Functions of Bone Supports soft tissue Protects vital organs cranium thoracic cavity Contains bone marrow Reservoir of Ca PO 4 to maintain constant concentrations in body fluids ID: 1041787
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1. BONE BONE and BLOODChapter- 5The most amazing story of bone histology! Dr. Duran Kala
2. Functions of BoneSupports soft tissueProtects vital organs (cranium, thoracic cavity)Contains bone marrowReservoir of Ca++, PO4 to maintain constant concentrations in body fluidsAllows body to move
3. Specialized CTCellsOsteoblastsOsteocytesOsteoclastsBone matrixCalcified material, lacunaeAnd more….CanaliculiPeriosteumEndosteum
4. Anatomy of a Long Bone
5. OsteoblastsSynthesize organic components of matrix (collagen type I, proteoglycans, glycoproteins.)Collagen forms osteoids: strands of spiral fibers that form matrixInfluence deposit of Ca++, PO4.Active vs inactive osteoblastsEstrogen, PTH stimulate activity
6. Osteoblasts
7. OsteocytesMature bone cells that sit in lacunaeGap junctions between osteocytes provide nutrition (15 cells in a row)Maintain bony matrix; long lived cellsStimulated by calcitonin; inhibited by Parat Hormone
8. Osteocyte with Cytoplasmic Extensions
9. Osteocytes with CanaliculiPhotomicrograph of dried bone ground very thin. The lacunae and canaliculi filled with air deflect the light and appear dark, showing the communication between these structures through which nutrients derived from blood vessels flow. Medium magnification.
10. OsteoclastsDerived from monocytes; engulf bony material Active osteoblasts stimulate osteoclast activityLarge, branched, motile cellsSecrete enzymes that digest matrix
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12. Osteoclasts
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14. Bone Resorption
15. RemodelingOn this image, the deepest red color is bone while pink represents either fibrocartilage (i.e., collagen within cartilage) or mineralized cartilage. The central clearing represents theinvasion of bone into calcified cartilage. Osteblasts are laying down new bone toward the left of the upper boundary of this cavity. Octeoclasts are removing previously-formed bone .
16. Bone Replacing Cartilage
17. Remodeling Bone
18. 1-Intermembraneous Ossification
19. 2-Endochondral Ossification
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21. PeriosteumMesenchymeFibroblastsOsteoprogenitorcells
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26. OsteonLong cylinder parallel to long axis of diaphysisConsists of:Haversian canal with nerves, blood vessels; lamellae with osteocytes Haversian canals communicate with marrow cavity, periosteum, other canals through Volkmann’s canals
27. Compact Bone
28. OSTEONS (wow!)
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30. Canaliculi between Osteocytes
31. BLOODBlood is sometimes considered to be a fluid connective tissue because of the mesenchymal origin of its cells and a low ratio of cells to liquid intercellular substance, the blood plasma. In human adults about 5 liter of blood contribute 7-8 % to the body weight of the individual.
32. Functions Of BloodTransport Protection Regulation
33. Functions Of BloodBlood carries:oxygen from the lungs to other tissues - it carries carbon dioxide back to the lungsdissolved foods from the gut to different parts of the bodywaste products to the kidneys hormones and antibodies around the bodyBlood contains:platelets and fibrinogen to make it clot, preventing severe loss of blood after injurywhite blood cells which protect us against germsBlood helps:to keep our body temperature constant by allowing us to retain or lose heatto control the amount of water and other chemicals in different parts of the body
34. BloodFormed elementsErythrocytes (red blood cells)99% of cellsCarry oxygenLeukocytes (white blood cells)Protect against infection and cancerPlatelets (cell fragments)Blood clottingPlasma55% of blood volumeWater (90%)ElectrolytesPlasma proteinsAlbuminFibrinogenGlobulinsSubstances transported by bloodNutrientsWaste productsRespiratory gasesHormones
35. Erythrocytes (Red blood cells) Numerous 4.8-5.4 million/mm3 Biconcave shape increases surface area 20-30%. Readily deform and pass through capillaries.Cytoskeleton is unique. Spectrin is major protein.Mature cell has no nucleus, organelles.Hemoglobin.Energy from anaerobic respiration of glucose. (No mitochondria present.)Lifespan is 120 days. Removed by spleen and liver.
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37. Leukocytes6-10,000 per µLGranulocytes (polymorphonuclear leukocytes)neutrophils 60-70%eosinophils 2-4%basophils 0.5-1%Agranulocyteslymphocytes 20-30%monocytes 3-8%
38. Cell type FunctionAppearanceNeutrophils Phagocytize bacteria and cellular debris Multilobed nucleus (usually 1-5), 10-12μm Eosinophil Fight parasitic worms and allergic responses Bilobed nucleus, cytoplasm filled with orange-red granules,11-14 μm Basophils Release chemicals (histamine,serotonin)that play role in inflammatory and allergic reactions Bilobed nucleus, Cytoplasm filled with violet-blue granules, 8-10 μm Lymphocytes T cell aattack invaders,B cells release free floating antibodies that attack specific invaders. Large, round,dark-staining nucleus. Size is quite variable, 6-11μm Monocytes Macrophages,highly phagocytic Kidney shaped or raound nucleus, large amount of cytoplasm, 12-20μm
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40. PlateletsPlatelets are cell fragments Blood normally contains 150,000 to 450,000 per microliter They have an essential role in blood clottingFibrinogen is turned into fibrin
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