lecture 4

• What are the two skeletal systems?

  Axial and appendicular systems
• What is the primary function of the skeletal system?

  It serves as the body's central framework
• What components make up the skeletal system?

  Bones, ligaments, joints, and cartilage
• What are the main functions of bones?

  Protection, locomotion, and manipulative functions
• What is the term for the relationship between the skeletal system and muscles?

  Musculoskeletal system
• How many bones are in the axial system?

  80 bones
• What are the three regions of the axial system?

  Skull, vertebral column, and thoracic cage
• What does the appendicular system consist of?

  126 bones appended to the axial skeleton
• What is the primary composition of the human skeleton at the beginning of development?

  Mainly cartilage
• What are the three types of cartilage?

  Hyaline, elastic, and fibrocartilage
• Where is hyaline cartilage found?

  Covers ends of bones at joints
• What is the function of fibrocartilage?

  Withstands high pressure
• What are the main functions of bones?

  Support, protect organs, and allow movement
• What is the role of osteoblasts?

  Bone forming cells that secrete bone matrix
• What is ossification?

  The process of bone formation
• What is the main type of bone formation?

  Endochondral ossification
• What are the five steps of endochondral ossification?

  1. A bone collar forms around hyaline cartilage
  2. The cartilage degrades
  3. Holes in calcified cartilage fill with spongy bone
  4. Spongy bone is broken down, forming the medullary cavity
  5. Spongy bone forms again and is retained
• What does bone remodeling involve?

  Deposition and removal of bone material
• How much of an adult's skeleton is replaced each year?

  5-10%
• What is the first step in repairing a fracture?

  Reduction of bone ends
• What are the four stages of bone fracture healing?

  1. Blood clot forms from torn vessels
  2. Fibroblasts deposit collagen fibers
  3. Osteoblasts deposit spongy bone
  4. Bone remodeling regulates density
• What is osteoporosis?

  A disorder with faster bone resorption than deposition
• What are risk factors for osteoporosis?

  Age, genetics, low-calcium diet
• What characterizes Paget's disease?

  Excessive and deregulated bone deposition
• What is the role of ligaments in joints?

  Help hold bones and joints in place
• How many joints are in the human body?

  350 joints
• What are the technologies used to image the skeletal system?

  • X-rays
  • PET scans
  • CT scans
  • MRI scans
• What is the most widely used biomaterial for orthopedic implants?

  Titanium
• What is the lifespan of titanium implants?

  Around 15 years
• What is the process of cartilage tissue engineering?

  1. Extract stem cells and chondrocytes
  2. Purify chondrocytes and stem cells
  3. Culture cells in vitro
  4. Mix with hydrogel
  5. Inject into patient
• What is the purpose of self-assembled systems in bone regeneration?

  • Stimulate bone re-growth
  • Extend growth factor lifespan
  • Form a matrix for slow release
• What do PET scans use for imaging?

  Radioactive tracers
• What is the primary component of the bone matrix?

  Minerals and collagen fibers
• What is the role of osteocytes?

  Regulate and maintain the bone matrix
• What happens to osteoclast activity in late Paget's disease?

  It reduces, leading to increased bone thickening
• What is the significance of the medullary cavity in bones?

  It contains bone marrow
• What is the primary function of spongy bone?

  To keep bones light while maintaining strength
• What is the role of bone lining cells?

  Thought to regulate bone matrix remodeling
• What is the significance of the collagen fibers in the bone matrix?

  They provide a tension-resistant network
• What is the relationship between osteoblasts and osteoclasts during remodeling?

  Osteoblasts follow osteoclasts to deposit new matrix