Skeletal System Hand Out


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Skeletal System Hand Out

  1. 1. Jaycris C. Agnes Made Easy for Anatomy and Physiology Students
  2. 2. 2. Skeletal System Learning Objectives: At the end of the discussion the students must be able to: • Enumerate the major roles of skeletal system and its parts, • Explain the process of bone formation, remodelling, repair and aging; and • Acclaim the roles of skeletal system to human survival. Topic Outline: I. Function of Skeletal System a. Bones b. Cartilages c. Tendons and Ligaments d. Joints II. General Features of Bone a. Parts of Bone b. Bone Cells c. Bone Surface Markings d. Bone Ossification, Remodelling and Repair e. Types of Bones III. General Consideration of Bone Anatomy Skeletal System: Jaycris C. Agnes 3SED-SC
  3. 3. 3. a. Division of Human Skeleton IV. Bone and Calcium Homeostasis V. Articulation VI. Effects of Aging on the Skeletal System I. Function of the Skeletal System A. Bones Mechanical • Protection — bones can serve to protect internal organs, such as the skull protecting the brain or the ribs protecting the heart and lungs. • Structure — bones provide a frame to keep the body supported. • Movement — bones, skeletal muscles, tendons, ligaments and joints function together to generate and transfer forces so that individual body parts or the whole body can be manipulated in three-dimensional space. The interaction between bone and muscle is studied in biomechanics. • Sound transduction — bones are important in the mechanical aspect of overshadowed hearing. Synthetic • Blood production — the marrow, located within the medullary cavity of long bones and interstices of cancellous bone, produces blood cells in a process called hematopoiesis. Metabolic Skeletal System: Jaycris C. Agnes 3SED-SC
  4. 4. 4. • Mineral storage — bones act as reserves of minerals important for the body, most notably calcium and phosphorus. • Growth factor storage — mineralized bone matrix stores important growth factors such as insulin-like growth factors, transforming growth factor, bone morphogenetic proteins and others. • Fat storage — the yellow bone marrow acts as a storage reserve of fatty acids. • Acid-base balance — bone buffers the blood against excessive pH changes by absorbing or releasing alkaline salts. • Detoxification — bone tissues can also store heavy metals and other foreign elements, removing them from the blood and reducing their effects on other tissues. These can later be gradually released for excretion. • Endocrine organ — bone controls phosphate metabolism by releasing fibroblast growth factor – 23 (FGF-23), which acts on kidneys to reduce phosphate reabsorption. Bone cells also release a hormone called osteocalcin, which contributes to the regulation of blood sugar (glucose) and fat deposition. Osteocalcin increases both the insulin secretion and sensitivity, in addition to boosting the number of insulin-producing cells and reducing stores of fat. B. Cartilage • Cartilage provides a model for bone growth and formation, provides a smooth cushion between adjacent bones, and provides firm and flexible support. C. Tendons and Ligaments • Tendons attach muscles to bones, and ligaments attach bones to bones. D. Joints • Joints allow movement between bones. II. General Features of the Bone A. Parts of Bone Major Parts of the Bone: Skeletal System: Jaycris C. Agnes 3SED-SC
  5. 5. 5.Skeletal System: Jaycris C. Agnes 3SED-SC Compact Bone Compact bone makes up the outer layer of all bones. Although it looks dense and solid, It is full of holes for nerves and blood vessels. Spongy Bone Spongy bone contains flat and needlelike structures that resist stress. Red bone marrow may fill the open spaces in some bones. Central Cavity Central cavities in long bones usually contain yellow bone marrow (fat). Outer Membrane An outer membrane covers most of a long bone. The inner portion of a membrane contains cells that build up and breakdown bone.
  6. 6. 6. B. Bone Cells There are several types of cells constituting the typical bone:  Osteocytes • Mature bone cells  Osteoblasts Skeletal System: Jaycris C. Agnes 3SED-SC
  7. 7. 7. • Bone-forming cells  Osteoclasts • Bone-destroying cells • Break down bone matrix for remodeling and release of calcium C. Bone Surface Markings Bones have characteristic surface markings Structural features adapted for specific functions There are two major types of surface markings: 1) Depressions and openings Allow the passage of blood vessels and nerves or form joints 2) Processes Projections or outgrowths that form joints or serve as attachment points for ligaments and tendons Skeletal System: Jaycris C. Agnes 3SED-SC
  8. 8. 8. D. Bone Ossification, Remodelling and Repair  Bone Ossification The formation of bone during the fetal stage of development occurs by two processes: Intramembranous ossification and endochondral ossification. Intramembranous ossification Skeletal System: Jaycris C. Agnes 3SED-SC
  9. 9. 9. Intramembranous ossification mainly occurs during formation of the flat bones of the skull but also the mandible, maxilla, and clavicles; the bone is formed from connective tissue such as mesenchyme tissue rather than from cartilage. The steps in intramembranous ossification are: 1. Development of ossification center 2. Calcification 3. Formation of trabeculae 4. Development of periosteum Endochondral ossification Endochondral ossification, on the other hand, occurs in long bones and most of the rest of the bones in the body; it involves an initial hyaline cartilage that continues to grow. The steps in endochondral ossification are: 1. Development of cartilage model 2. Growth of cartilage model 3. Development of the primary ossification center 4. Development of the secondary ossification center 5. Formation of articular cartilage and epiphyseal plate  Remodelling Skeletal System: Jaycris C. Agnes 3SED-SC
  10. 10. 10. Bone remodelling consists of removal of existing bone by osteoclasts and deposition of new bone by osteoblasts.  Repair During bone repair, cells move into the damaged area and form a callus, which is replaced by bone. E. Types of Bone Long Bones Skeletal System: Jaycris C. Agnes 3SED-SC
  11. 11. 11. • Greater length than width and are slightly curved for strength • Femur, tibia, fibula, humerus, ulna, radius, phalanges Short bones • Cube-shaped and are nearly equal in length and width • Carpal, tarsal Flat bones • Thin and composed of two nearly parallel plates of compact bone tissue enclosing a layer of spongy bone tissue • Cranial, sternum, ribs, scapulae Irregular bones • Complex shapes and cannot be grouped into any of the previous categories • Vertebrae, hip bones, some facial bones, calcaneus Sesamoid bones • Protect tendons from excessive wear and tear • Patellae, foot, hand III. General Consideration of Bone Anatomy A. Division of Human Skeleton • The human skeleton consists of 206 named bones • Bones of the skeleton are grouped into two principal divisions: Axial skeleton  Consists of the bones that lie around the longitudinal axis of the human body  Skull bones, auditory ossicles (ear bones), hyoid bone, ribs, sternum (breastbone), and bones of the vertebral column Appendicular skeleton  Consists of the bones of the upper and lower limbs (extremities), plus the bones forming the girdles that connect the limbs to the axial skeleton Skeletal System: Jaycris C. Agnes 3SED-SC
  12. 12. 12.Skeletal System: Jaycris C. Agnes 3SED-SC
  13. 13. 13.Skeletal System: Jaycris C. Agnes 3SED-SC
  14. 14. 14. IV. Bone and Calcium Homeostasis 1. Osteoclasts remove calcium from bone, causing blood calcium levels to increase. 2. Osteoblasts deposit calcium into bone, causing blood calcium levels to decrease. 3. Parathyroid hormones increases bone breakdown, whereas calcitonin decreases bone breakdown. V. Articulations An articulation, or joint, is a place where two bones come together. A. Kinds of Joint based on movement:  Synarthrosis - non movable joints  Amphiarthrosis - slightly movable joints  Diarthrosis - freely movable joints B. Kinds of Joint based on structural connection: Skeletal System: Jaycris C. Agnes 3SED-SC
  15. 15. 15.  Fibrous Joints - consist of two bones that are united by fibrous tissue and that are united by fibrous tissue and that exhibit little or no movement.  Sutures are fibrous joints between the bones of skull.  Syndesmoses are fibrous joints in which the bones are separated by some distance and are held together by ligaments. An example is the fibrous membrane connecting most of the distal parts of the radius and ulna.  Gomphoses consist of pegs fitted into sockets and held in place by ligaments. The joint between a tooth and its sockets is a gomphosis.  Cartilaginous Joints - unite two bones by means of cartilage. Only slight movement can occur at these joints .  Examples are the cartilage in the epiphyseal plates of growing long bones and the cartilages between the ribs and the sternum.  Synovial Joints - are freely movable joints that contain synovial fluid in cavity surrounding the ends of articulating bones. Skeletal System: Jaycris C. Agnes 3SED-SC
  16. 16. 16. • Kinds of Synovial Joints: Skeletal System: Jaycris C. Agnes 3SED-SC
  17. 17. 17. C. Types of Movement Skeletal System: Jaycris C. Agnes 3SED-SC
  18. 18. 18.Skeletal System: Jaycris C. Agnes 3SED-SC
  19. 19. 19. VI. Effects of Aging on the Skeletal System and Joints 1. Bone matrix becomes more brittle and decreases in total amount during aging. 2. Joints lose articular cartilage and become less flexible. ______________________________________________________________________________ Submitted to Ms. Jaydee S.M. de Leon Anatomy and Physiology Professor Bibliography: •,%20the%20free %20encyclopedia.htm •,%20the%20free %20encyclopedia.htm • John Wiley & Sons, Inc. Skeletal System: Jaycris C. Agnes 3SED-SC
  20. 20. 20. • Starr, Cecie. (2008) Human Biology 7th Edition. Thomson Learning. • Bryan H. Derrickson; Tortora, Gerard J. (2005). Principles of anatomy and physiology. New York: Wiley • Seeleys et al, Essentials of Anatomy and Physiology. 6th edition Skeletal System: Jaycris C. Agnes 3SED-SC