Bones - Learning Outcomes, PDF

**[Bones ]** **[Learning outcomes ]** **1. Describe the Composition and Development of Bone:** - **Composition**: - **Bone Cells**: - **Osteoblasts**: Bone-forming cells that produce the bone matrix. - **Osteocytes**: Mature bone cells that maintain the...

**[Bones ]** **[Learning outcomes ]** **1. Describe the Composition and Development of Bone:** - **Composition**: - **Bone Cells**: - **Osteoblasts**: Bone-forming cells that produce the bone matrix. - **Osteocytes**: Mature bone cells that maintain the matrix and reside in lacunae. - **Osteoclasts**: Large, multinucleated cells responsible for bone resorption and remodeling. - **Bone Matrix**: - **Inorganic Components**: Mainly **hydroxyapatite** crystals (calcium phosphate), giving bone its hardness and strength. - **Organic Components**: Primarily **collagen fibers**, providing flexibility and tensile strength. - **Water**: Constitutes around 20% of bone's total composition. - **Bone Development**: - Bone formation starts before birth and continues until approximately **25 years of age**. - **Intramembranous Ossification**: Bone forms directly from mesenchymal tissue (e.g., flat bones like the skull). - **Endochondral Ossification**: Bone forms from a cartilage template (e.g., long bones like the femur). **2. Identify the Different Types of Bones and Where They are Found:** 1. **Long Bones**: - **Structure**: Consist of a long shaft (diaphysis) and two articular ends. - **Location**: Found in the limbs (e.g., **femur**, **tibia**, **humerus**). 2. **Short Bones**: - **Structure**: Cube-shaped. - **Location**: Found in the **wrist** (carpals) and **ankle** (tarsals). 3. **Flat Bones**: - **Structure**: Thin, flat, and often curved. - **Location**: Found in the **skull** (e.g., parietal and occipital bones), **sternum**, and **ribs**. 4. **Irregular Bones**: - **Structure**: Irregular shapes. - **Location**: Found in the **spine** (vertebrae) and **pelvis**. 5. **Sesamoid Bones**: - **Structure**: Embedded in tendons. - **Location**: Found in the **patella** (kneecap). **3. Be Aware of the General Function of the Bone Types in the Body:** 1. **Long Bones**: - Provide **strength**, **structure**, and **mobility**. - Act as levers for movement in combination with muscles. 2. **Short Bones**: - Provide **support** and **stability** with little movement. 3. **Flat Bones**: - Protect internal organs (e.g., skull protecting the brain). - Provide broad surfaces for muscle attachment (e.g., ribs). 4. **Irregular Bones**: - Protect the spinal cord and provide support and flexibility for the body. 5. **Sesamoid Bones**: - Reduce friction and modify pressure in tendons during movement (e.g., patella protects the knee joint). **4. Describe the Process of Bone Healing and the Factors that Influence Healing:** - **Stages of Bone Healing**: 1. **Primary Callus Formation**: A **fibrocartilaginous callus** forms during the first months after injury. 2. **Woven Bone Formation**: Dead bone is resorbed and replaced by spongy bone. 3. **Bony Secondary Callus**: Spongy bone is gradually replaced by **lamellar bone**, uniting the fracture. 4. **Bone Remodeling**: The final stage where the bone regains its original shape, which can take years. - **Factors that Influence Healing**: 1. **Factors that Delay Healing**: - Infection, **poor blood supply**, **tissue fragments**, **older age**, certain **medications** (e.g., steroids), and poor host immune response. 2. **Factors that Improve Healing**: - **Limited movement** and rest, **pain management**, **nutrition**, appropriate **movement** under medical supervision, and age (younger people heal faster). **5. Recognize Some Common Bone Diseases Patients May Present With:** 1. **Fractures**: Broken bones of various types, such as simple, compound, or comminuted fractures. 2. **Osteoporosis**: Reduced bone density and strength, leading to brittle bones and a higher risk of fractures. 3. **Osteomyelitis**: A serious infection of the bone, often caused by bacteria like **Staphylococcus aureus**. 4. **Osteitis**: Inflammation of bone, such as in **Paget's disease**. 5. **Acromegaly**: Overgrowth of bones in the face, hands, and feet due to excessive growth hormone. 6. **Fibrous Dysplasia**: Abnormal growth or swelling of bone, replacing normal bone with fibrous tissue. 7. **Rickets**: A condition in children where bones fail to develop properly due to **vitamin D deficiency**. 8. **Multiple Myeloma**: A type of cancer affecting the plasma cells in the bone marrow. 9. **Bone Cancer**: Primary bone cancers (e.g., **osteosarcoma**, **chondrosarcoma**), though most bone cancers are secondary and have spread from other organs (e.g., **breast**, **lung**, or **prostate cancer**).