PCBI101: SKELETAL

• Skeletal System


  The system of bones, cartilage, and ligaments that provides support, protection, movement, and other functions for the human body

  
• Functions of the Skeletal System


  • Support
  • Protection
  • Movement
  • Storage
  • Blood cell production (hematopoiesis)
• Support


  • Rigid strong bones for bearing weight and major supporting tissue of the body
  • Cartilage provides firm yet flexible support within certain structures (e.g. nose and external ears)
  • Ligaments are strong bands of fibrous connective tissue that attach to bone and hold them together

  
• Protection


  • The hardness of the bone contributes to its ability to protect the vital organs of the body from injury (e.g. cranial bones protect the brain)

  
• Movement


  • Skeletal muscles attach to bones by tendons, when muscles contract they pull on bones and together they produce movement
• Storage


  • Fat is stored in the internal cavities of bones
  • Stores several minerals especially calcium and phosphorus
  • Important in maintaining homeostasis of minerals in the blood with minerals stored in the bone are released in response to body's demand
• Blood cell production (hematopoiesis)


  • Many bones contain cavities filled with bone marrow that gives rise to blood cells and platelets

  
• Osteology


  The study of bone structure and treatment of bone disorder

  
• Bone ossification (osteogenesis)


  The formation of bone by osteoblast

  
• Types of bone ossification


  • Intramembranous ossification
  • Endochondral ossification

  
• Intramembranous ossification


  A process of bone development from fibrous membrane, involved in the formation of the flat bones of the skull, the mandible and clavicles

  
• Endochondral ossification


  A process of bone development from hyaline cartilage, all of the bones of the body, except for the flat bones of the skull, mandible and clavicles are formed through endochondral ossification

  
• Appositional growth


  1. Formation of new bone on the surface of existing bone

  2. Osteoblasts deposit new bone matrix on the surface of bones between the periosteum and the existing bone matrix

  3. Responsible for the increase in width or diameter of long bones and most growth of other bones

  
• Endochondral growth


  1. Growth of cartilage in the epiphyseal plate and its eventual replacement by bone

  2. Responsible for the increase in the length of the bone

  3. Bones continue to grow in length until early childhood, the rate of growth is controlled by hormones

  
• Bone remodeling


  The removal of old bone by cells called osteoclast and the deposition of new bone by osteoblast, occurs in all bone and is responsible for bone growth, changes in bone shape, adjustment of bone to stress, bone repair, and calcium ion regulation

  
• Bone remodeling process


  1. Resorption - osteoclasts digest old bone

  2. Reversal - mononuclear cells appear on the bone surface

  3. Formation - osteoblasts lay down new bone until the resorbed bone is completely replaced

  
• Bone repair (healing)


  A process in which a bone repairs itself following a bone fracture, involving the formation of a clot, callus, and the remodeling of cancellous bone to compact bone

  
• Bone and calcium homeostasis


  Bone serves as the major storage site for calcium, the movement of calcium in and out of bone helps determine blood calcium levels, calcium homeostasis is maintained by parathyroid hormone and calcitonin

  
• Achondroplasia


  A form of short-limbed dwarfism where the problem is not in forming cartilage but in converting it to bone

  
• Osteogenesis imperfecta


  A genetic disorder that results from a lack of protein collagen producing very brittle bones that are easily fractured

  
• Rickets


  Bones of children are inadequately mineralized causing softened, weakened bones, bowed legs and deformities, caused by insufficient calcium in the diet, or by vitamin D deficiency

  
• Osteomalacia


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

  
• Osteomyelitis


  Infection in bone caused by Staphylococcus bacteria, the bacteria can enter a bone by the bloodstream, injuries and surgery

  
• Osteoporosis


  A group of diseases in which bone reabsorption outpaces bone deposit, spongy bone of the spine is most vulnerable, occurs 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, brought on by congenitally malformed vertebra, chronic sciatica, paralysis of muscles on one side of the backbone, or poor posture
• Fracture


  A break in a bone, common types include simple, compound, compression, comminuted and greenstick
• Arthritis


  Joint inflammation, marked by pain, stiffness and swelling of the affected joint, may include one or several joints
• Osteoarthritis


  A degenerative joint disease in which the cartilage that covers the ends of the bones in the joint deteriorates, symptoms include pain, restriction of movement, formation of hard nobs

  
• Rheumatoid arthritis


  An 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, a small sac filled with fluid and located at friction points