L1 - Skeletal System | Anaphy

• Osteology - study of bone structure and treatment of bone disorder
• bone ossification - formation of bone by osteoblast
• bone ossification is also known as osteogenesis
• intramembranous ossification - bone development from fibrous membrane
• intramembranous ossification forms the flat bones of the skull, mandible and clavicles
• endochondral ossification - bone formation from hyaline cartilage
• endochondral ossification forms all of the bones of the body except for the flat bones of the skull
• appositional growth

  • formation of new bone on the surface of existing bone
  • responsible for the increase in width or diameter of long bones and most growth of other bones
• endochondral growth

  • growth of cartilage in the epiphyseal plate and its eventual replacement by bone
  • responsible for the increase in the length of the bone
• bone remodeling - the removal of old bone by cells called osteoclast and the deposition of new bone by osteoblast
• bone remodeling is responsible for bone growth, changes in bone shape, adjustment of bone to stress, bone repair, and calcium ion regulation
• resorption - osteoclasts digest old bones
• reversal - mononuclear cells appear on the bone surface
• formation - osteoblasts lay down new bone until the resorbed bone is completely replaced
• three phases of bone remodeling are resorption, reversal, and formation, respectively
• bone repair - a bone repairs itself following a bone fracture
• bone repair is also known as healing stage
• when a bone is broken, a clot forms in the damaged area
• process of bone repair

  1. callus forms, which is the zone of tissue repair between the two bone fragments
  2. osteoblasts enter the callus and form cancellous bone
  3. the cancellous bone is slowly remodeled to form compact bone the repair is complete
• bone serves as the major storage site for calcium
• the movement of calcium in and out of bone helps determine blood calcium levels
• calcium moves into bone as osteoblasts builds new bone
• calcium moves out of bone as osteoclasts breaks down bone
• calcium homeostasis is maintained by parathyroid hormone (PTH) and calcitonin
• achondroplasia

  • short-limbed dwarfism
  • "without cartilage formation"
  • the problem is not in forming cartilage but in converting it to bone
• osteogenesis imperfecta

  • "brittle bone disease
  • a genetic disorder that results from a lack of protein collagen producing very brittle bones that are easily fractured
• rickets

  • bowed legs and deformities of the pelvis, skull and rib cage are common
  • bones of children are inadequately mineralized causing softened, weakened bones
  • caused by insufficient calcium in the diet or by vitamin D deficiency
  • common in children
• osteomalacia

  • main symptom is pain when weight is put on the affected bone
  • bones are inadequately mineralized causing softened, weakened bones
  • caused by insufficient calcium in the diet, or by Vitamin D deficiency
  • common in adults
• osteomyelitis

  • infection in bone caused by Staphylococcus bacteria
  • the bacteria can enter a bone by the bloodstream, injuries and surgery
• osteoporosis

  • group of diseases in which bone resorption outpaces bone deposit
  • spongy bone of the spine is most vulnerable
  • most often in postmenopausal women
  • bones become so fragile that sneezing or stepping off a curb can cause fractures
• scoliosis - lateral curvature of the central part of the spine
• Causes of Scoliosis

  1. Congenitally malformed vertebra
  2. Chronic sciatica
  3. Paralysis of muscles on one side of the backbone
  4. poor posture
• osteoarthritis

  • "wear and tear" disease
  • a degenerative joint disease in which the cartilage that covers the ends of the bones in the joint deteriorates
  • Symptoms: pain, restriction of movement, formation of hard nobs
• rheumatoid arthritis - active chronic inflammatory autoimmune disease affecting synovial membrane
• gouty arthritis - a disease associated with an inborn error of uric acid metabolism
• bursitis - an acute or chronic inflammation of the bursa
• bursa - a small sac filled with fluid and located at friction points
• fracture - a break in a bone
• comminuted

  • bone breaks into many fragments
  • common in the aged since bones are brittle
• compression

  • bone is crushed
  • common in porous bones