Bone Anatomy and Disorders Quiz

Normal Bone Composition

• Normal bone is comprised of organic and inorganic matrix
• Organic matrix includes cells, type 1 collagen (90% of bone protein), and glycoproteins
• Inorganic matrix includes calcium, magnesium, potassium, chloride, sodium, and fluoride

Bone Functions

• Provides structural support for soft tissues, such as muscles
• Protects soft organs and tissues like the brain and bone marrow
• Acts as a mineral reservoir, regulating calcium and phosphate levels in the blood

Bone Cells

• Osteoblasts are responsible for bone formation
• Osteocytes maintain bone; they are former osteoblasts embedded in the matrix
• Osteoclasts are responsible for bone resorption

Hereditary Bone Disorder: Achondroplasia

• Long bones are short and thick, leading to dwarfism with short extremities
• Cranial and vertebral bones are typically unaffected, resulting in a relatively large head and trunk
• Intelligence, lifespan, and reproductive ability are normal in this condition

Osteoporosis

• A condition of decreased bone mass, also known as osteopenia
• Results in fragile bones prone to fracture from minimal impact trauma

Osteoporosis Causes

• Primary: Post-menopausal and senile (aging)
• Secondary: Various factors including metabolic diseases, gastrointestinal disorders, vitamin deficiencies, chronic illnesses, and drug use (e.g., corticosteroids)

Osteoporosis Symptoms and Diagnosis

• Fractures: Common in vertebrae (compression fractures), femoral neck (hip fractures), distal radius (Colles' fractures)
• Kyphosis and height loss: May occur
• X-rays: Show generalized radiolucency (thinning) of bone, indicative of osteopenia

Osteomalacia and Rickets

• Both conditions involve decreased bone mineralization in newly formed bone tissue
• Osteomalacia occurs in adults; rickets in children
• Typically caused by vitamin D deficiency or abnormal vitamin D metabolism

Osteonecrosis

• Also called avascular necrosis, this is ischemic necrosis characterized by bone infarction
• Mechanisms include vascular compression or disruption (e.g., after fracture)
• Other causes include steroid administration, thromboembolic disease, primary vessel disease (e.g., vasculitis), and sickle cell crisis

Osteomyelitis

• Inflammation of bone and marrow, often secondary to systemic infection but also occurs as a primary isolated infection
• Usually caused by pyogenic bacteria or Mycobacterium tuberculosis
• Can be acute or chronic, significantly impacting the affected tissue.

Osteoarthritis

• A degenerative joint disease
• Characterized by joint degeneration and loss of articular cartilage, without significant inflammation
• Risks increase with age; affects at least one joint in 80% of people over 70

Rheumatoid Arthritis

• Systemic chronic inflammatory disorder
• Characterized by progressive arthritis, production of rheumatoid factor, and extra-articular symptoms or involvement
• More prevalent in women at a 4:1 ratio compared to men, with highest incidence in the 20-50 age range

Target Tissues for Different Conditions

• Rheumatoid arthritis: Synovial tissue
• Osteoarthritis: Hyaline cartilage