Bone LS, Bone TS- discussion, viva
- What is bone?
- Bone is a specialized connective tissue.
- What are the components of bone?
- Bone consists of cells (osteoblast, osteocyte, osteoclast), fibers and extracellular matrix.
- Extracellular matrix-
- organic (coarse type I collagen fibers, sulfated glycosaminoglycans, hyaluronic acid, glycoproteins
- inorganic- calcium and phosphate together form hydroxyapatite crystals
- Why is bone hard?
- Bone is hard because of mineral deposition in the matrix. The hydroxyapatite crystals with collagen fibers makes the bone hard, durable and strong.
- What are the functions of bone?
- Bone is remodeled continuously due to mechanical stress, bone thinning due to age, fracture healing
- Calcium and phosphate are released into blood when needed to maintain proper levels
- Calcium is necessary for muscle contraction, blood coagulation, cell membrane permeability, transmission of nerve impulses
- What are the functions of the bone cells?
- Osteoblast- synthesize, secrete and deposit osteoid (uncalcified without minerals)
- Osteocytes- mature cells trapped in bone matrix
- Osteoclasts- large multinucleated cells, responsible for resorption (renew or restructure), remodeling of the bone and bone repair
- What is the arrangement of bone components in LS of bone?
- Haversian canals coarse longitudinally with parallely running lamellae, lacunae, canaliculi
- What is the function of Haversian canal and Volkmann's canal?
- Nutrition to the bone is supplied through blood vessels present in the Haversian canals and Volkmann's canals. Along with blood vessels, nerves and lymphatics are also present
- What is a lamella, lacuna, canaliculi?
- Lamella- thin plate of bone matrix
- Lacuna- space lodging osteocyte
- Canaliculi- tiny canals radiating from lacuna, penetrate lamellae and communicate with other canaliculi. They lodge the cytoplasmic processes of osteocytes which communicate with cytoplasmic processes of other osteocytes.
- What is osteon/ Haversian system?
- One Haversian system consists of Haversian canal with neurovascular structures in the center surrounded by concentric lamellae
- What are the different types of lamellae?
- Concentric lamellae- lamellae surrounding the Haversian canal
- Interstitial lamellae- lamellae present between the various osteons
- Inner circumferential lamellae- lamellae present surrounding the bone marrow/endosteum
- Outer circumferential lamellae- lamellae present deep to the periosteum
- What is periosteum?
- Periosteum is the connective tissue which surrounds the bone
- It has two layers outer fibrous layer and inner cellular layer
- Outer fibrous layer- formed by collagen fibers and fibroblasts
- Inner cellular layer- formed by the osteoprogenitor, osteoblast cells
- What is a lamella, lacuna, canaliculi?
- Lamella- thin plate of bone matrix
- Lacunae- spaces present between adjacent lamellae lodging osteocytes
- Canaliculi- tiny canals radiating from lacuna, penetrate lamellae and communicate with other canaliculi. They lodge the cytoplasmic processes of osteocytes which communicate with cytoplasmic processes of other osteocytes.
- What is Haversian canal and Volkmann's canal?
- Haversian canal- Central canal of the osteon running longitudinally which transmits blood vessels, nerves and lymphatics to provide nutrition to the bone
- Volkmann's canal- communicating channels between the Haversian canals, periosteum and endosteum
- What are Howship's lacunae?
- They are eroded shallow depressions which lodges osteoclasts
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