Artifact two

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Artifact two

  1. 1. Artifact Two –Skeletal Physiology
  2. 2. FOUR TYPES OF BONES:Short bones: carpals and tarsals (bones in your fingers and toes)Flat bones: Calvarium (skull bone), sternum, or scapulaLong bones: femur, tibia and fibula (all leg bones) or humerus, radius and ulna(arm bones)Irregular bones: bones that cant fit into the above categories: vertebrae(spine), hyoid, maxilla and mandible (jaw), and the bones of your sinuses: Six Major structures of a typical long bone:ethmoid, zygomatic, and sphenoid (1)Diaphysis: main or midsection/ shaft of a long bone. Made up of cortical boneand usually contains bone marrow and adipose tissue.Epiphyses: End of a long bone that is originally separated from the main bone.(1)Articular Cartilage: smooth, white tissue that covers the ends of bones in joints.(1)Periosteum: a specialized connective tissue covering all bones and havingbone-forming potentialities. (1)Medullary (marrow) Cavity: space in a bone where a soft, flexible substancecalled marrow is stored. (1)
  3. 3. Major constituents of bone as a tissue:Endosteum: thin layer of cells lining the medullary cavity of a bone. (1)Composition of bone Matrix: The release of these growth factors from the bonematrix could cause the proliferation of osteoblast precursors. (1)Inorganic matrix: structural strength (1)Measuring bone mineral density: Proxy measurement for bone strength. (1)Organic Matrix: elements of a bone are primarily collagen. It allows bones toflex. (1) TYPES OF BONE CELLS:Osteoblasts- are small cells that synthesize and secrete a specialized organicmatrix, called Osteoid, that is an important part of the ground substance ofbone.Osteoclasts- are giant Multinucleate cells that are responsible for the activeerosion of bone minerals.Osteocytes- Are mature, nondividing osteoblasts that have become surroundedby matrix and now lie within lacunae. (1) © (6) © (7)
  4. 4. HaversianSystemThe osteon or Haversian system is the fundamental functional unit of compactbone. Osteons are roughly cylindrical structures that are typically severalmillimeters long and around 0.2mm in diameter. They are present in manybones of most mammals and some bird, reptile and amphibian species. (1) © (5)Lacunae Containing Osteocytes- (Latin for the Lakes) Small Spaces containingTissue fluid in which bone cells lie imprisoned between the hard layers of thelamellae.Lamellae-Concentric, Cylinder-shaped layers of calcified matrixCanaliculi- Ultrasmall canals radiating in all directions from the Lacunae andConnecting them to each other and into a larger canal, The Haversian canal.Haversian Canal- Extends lengthwise through the center of each Haversiansystem; contains blood vessels, Lymphatic Vessels, and nerves from the
  5. 5. HaversianCanal; nutrients and oxygen move through canaliculi to the Lacunaeand their bone cells--- a short distance of about 0.1 mm or less.Volkmann’s canal and communicating canals that contain nerves and vesselsthat carry blood and lymph from the exterior surface of the bone to theOsteons.Osteons- Compact bones that contain many cylinder-shaped structural units. Homeostatic Functions of Bones 1. Support – bones act as the framework for our body, creating the shape of our skeleton 2. Protection –our bones help protect our vital organs, like the rib cage protects our lungs and heart 3. Movement – Our muscles are attached to our bones which allow us to move at the joints 4. Mineral Storage – Bones store many minerals, such as calcium and phosphorus. Homeostasis blood calcium concentration is vital to living, it has to be equal levels in the bone and the blood (1.) 5. Hematopoiesis (blood cell formation)– a vital process carried out by red bone marrow(1.)
  6. 6. Ossification Intramembranous ossification takes place in a connective tissue membrane. Itusually involves the flat bones while endochondral ossification usually deals with longbones. Intramembranous ossification deals with the fetus. Ground substance and thecollagenous fiber make the organic bone matrix. Calcification of the matrix formsand continues until the trabeculae appear and form spongy bone. (1) Endochondral ossification is from cartilage models with bone formationspreading from the center to the ends. The bone continues to grow through primaryossification center and secondary ossification center. An epiphyseal plate remains Repair of Bone Fracturesbetween the epiphysis and diaphysis. (1)A bone fracture tears and destroys blood vessels that carry nutrients to osteocytes,which is what initiates the repair sequence. The fracture itself is the first step in thebone repair process. The next step is the formation of a fracture hematoma. Then it isthe formation of internal and external callus, which bind the broken fragmenttogether which stabilizes the wound and allows the healing process to procede. Andafter that the bone remodeling is complete. (1)
  7. 7. CARTILAGE Hyaline Cartilage - provides firm support with some pliability. It coversthe ends of the long bones as articular cartilage , providing springy padsthat absorb compression at joints . Has resilient cushioning properties ;resists compressive stress. Supports the tips of the nose , connects the ribsto the sternum , and supports most of the respiratory system passages. Theskeletal hyaline comes during childhood as the epiphyseal plates , providefor continued growth in length. Covers the ends of long bones in jointcavities ; forms costal cartilages of ribs , nose , trachea , and larynx. (1)Elastic Cartilage - Found where strength and exceptional stretch ability areneeded. Elastic cartilage forms the skeletons of the external ear and theepiglottis. Maintain the shape of a structure while allowing great flexibility.Similar to hyaline but more elastic fibers in matrix. (1)Fibrocartilage- Compressible and resists tension well , found where strongsupport and the ability to with strand heavy pressure are required. EX: thespongy cartilage of the knee , Intervertebral discs Strength with the abilityto absorb compressive shock.Less firm than the hyaline; thick collagen fibers predominate. (1)
  8. 8. Growth of CartilageInterstitial Growth: The cartilage cells within the substance of the tissuemass divide and begin to secrete additional matrix. Internal division ofchondrocytes is possible because of the soft, pliable nature of cartilagetissue. This type of growth is mostly seen during childhood and earlyadolescence, when the majority of the cartilage is still soft and capable ofexpansion from within (1)Appositional Growth: This occurs when chondrocytes in the deep layer ofthe perichondrium begin to divide and secrete additional matrix. The newmatrix is then deposited on the surface of the cartilage, causing it toincrease in size. This type of growth is unusual in early childhood but, onceit starts it continues beyond adolescence and throughout an individual’slife. (1) Classification of jointsJoints are classified into 3 major categories using a structural or a functionalscheme. If a structural classification is employed, joints are namedaccording to the type of connective tissue that joins the bones together,(fibrous and cartilaginous) or by the presence of a fluid-filled joint capsule.(synovial joints) (1) If a functional classification scheme is used, joints are divided into threeclasses according to the degree of movement they permit. (synarthroses,amphiarthroses, and diarthroses) (Immovable, slightly movable and freelymoveable) (1)
  9. 9. Fibrous joints are synarthroses. The articulating surfaces of these joints fitclosely together.The three types of fibrous joints are:Syndesmoses- Joints on which fibrous bands connect two bonesSutures- Found only in the skull, teeth like projections jut out fromadjacent bones and interlock with each other with only a thin layer offibrous tissue between them. (1)Gomphoses: unique joints that occur between the root of a tooth and thealveolar process of the mandible and maxilla. (1)Cartilaginous Joints are amphiarthroses: The bones that articulate to form acartilaginous joint are joined together by either hyaline cartilage orfibrocartilage. There are two types of theseSychondroses: Joints that are characterized by the presence hyaline cartilagebetween articulating bonesSymphyses: a joint in which a pad or disk of fibrocartilage connects twobones (1) Synovial jointsThey are the body’s most moveable, numerous and the most anatomicallycomplex joints.Seven types of structures for synovial joins
  10. 10. joint capsules, synovial membrane, articular cartilage, joint cavity, menisci(articular disks), ligaments and bursea(1)Synovial joints are divided into three main groups: Uniaxial, biaxial, andmultiaxialUniaxial joints: Synovial Joints that permit movement around only oneaxis and in only one plane. EX: Hinge Joints and Pivot JointsBiaxial joints: Diaphroses that permit movement around two perpendicularaxes in two perpendicular planes EX: Saddle Joints and Condyloid JointsMultiaxial Joints: Joints that permit movement around three or more axesand in three or more planes EX: Ball and Socket joints and Gliding joints(1) QuestionsThe 2 functions that have gone awry that cause the need for a bonemarrow transplant and osteoporosis are low bone mineral density due tonot enough calcification. The normal process should be the calcification ofhighly specialized crystals of calcium and phosphate. A bone marrowtransplant is performed if someone has damaged bone marrow, normallyred blood marrow produces red blood cells and yellow bone marrow issaturated in fat not involved in blood cell production but can change to redbone marrowif needed. (1)
  11. 11. A fracture in the epiphyseal plate can cause problems in kids becausetheir bones have not finished growing, the epiphyseal plate is there as abarrier between the shaft and end of the bone and if it gets fractured it cancause problems in the ossification process. As you get older your bones start to weaken and you start to havebone loss. With this bone loss comes changes in your skeletal frame, youget shorter and can have a humped back. You also have remodeling of incompact bone which involves new haverian systems. (1)

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