Bone Tissue Notes PDF

# Bone Tissue ## Introduction - **Osteo** refers to bone. - **-cytes** refers to cells. *** ## Bone Tissue Components ### Osteoblasts - resemble fibroblasts - produce collagen I, proteoglycans, and glycoproteins - the matrix produced by blasts is called **osteoid** - osteoid is uncalcified an...

# Bone Tissue ## Introduction - **Osteo** refers to bone. - **-cytes** refers to cells. *** ## Bone Tissue Components ### Osteoblasts - resemble fibroblasts - produce collagen I, proteoglycans, and glycoproteins - the matrix produced by blasts is called **osteoid** - osteoid is uncalcified and organic - Osteoblasts become **osteocytes** when surrounded by calcified matrix. ### Osteocytes - maintain bone matrix ### Osteoclasts - large, multinucleated cells - derived from the monocyte lineage - create **Howship lacunae** when resorbing bone - responsible for resorption of both mineral and organic components of bone *** ## Composition of Bone Matrix - **Organic** - 90% collagen type I - proteoglycans - glycoproteins - **Inorganic** - hydroxyapatite - calcium phosphate - magnesium phosphate - sodium, potassium, and bicarbonate ions *** ## Bone Remodeling - **Osteoblasts** and **osteoclasts** work together to remodel bone. - **Modeling**: new bone is formed. - **Remodeling**: existing bone is removed, and new bone is deposited. *** ## Osteoporosis - **Osteoporosis** is a disease characterized by low bone mass and structural deterioration that leads to increased bone fragility and susceptibility to fracture. - **Osteocytes** act as mechanosensors that detect changes in bone strain and influence the activity of osteoblasts and osteoclasts. *** ## Bone Growth - Bones grow longer **longitudinally** at the **growth plate** until puberty. - Bones also **increase in diameter** at the **periosteum**. ### Types of Secondary Bone - **Compact bone**: dense, solid bone found in the diaphysis of long bones. It is also known as **cortical bone**. - **Trabecular bone**: porous, spongy bone found in the epiphysis of long bones. It is also known as **cancellous bone**. *** ## Endosteum - inner lining of bone that is made up of a thin layer of connective tissue. ## Periosteum - outer lining of bone that is made up of a dense layer of connective tissue. - contains progenitor cells. *** ## Tetracycline - a drug that can be used as a bone marker - it is incorporated into bone matrix during periods of active bone formation. Tetracycline can be used to analyze bone growth and remodeling. *** ## Haversian system - This system consists of concentric rings of lamellae which surround a central canal called the Haversian canal. - The Haversian canal contains blood vessels, nerves, and lymphatic vessels. - Between the lamellae are spaces filled with osteocytes that are interconnected by **canaliculi**. ## Volkmann's canals - **Volkmann's canals** are transverse channels that connect adjacent Haversian canals, allowing for communication and nutrient diffusion across the osteon. *** ## Techniques for Studying Bone - **Light microscopy**: used to visualize the overall structure of bone and the different cell types. - **Scanning electron microscopy**: provides high-resolution images of the surface of bone, revealing details of the matrix and the cells. - **X-ray imaging**: a technique used to visualize the density of bone and detect bone fractures. - **Bone biopsies**: samples of bone are removed for analysis of their mineral composition, cell types, and other properties. - **CT scans**: provide three-dimensional images of the internal structure of bone and can be used to diagnose bone diseases. *** ## Future Directions in Bone Research - Developing new drugs and therapies to treat bone diseases - Understanding the role of the immune system in bone health - Developing new materials and techniques for bone regeneration.