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Musculo-Skeletal system • http://kidshealth.org/PageManager.jsp?lic=1& article_set=59302&cat_id=20607 • Skeletal system • http://www.youtube.com/watch?v=UGTenIDJ BwU Evolution of the System • Muscles evolved 500-800 million yrs. ago • Actin muscle protein structure resembles mreB structure in bacteria – mreB is used to maintain shape of the bacterial cell • Myosin resembles Muk and SMC in bacteria – Muk condenses DNA after DNA replication • 500 million yrs. ago, striated and smooth muscle diverged Types of Skeletons • Hydrostatic Skeleton – Fluid-filled body cavity – Found in Porifera, Nematoda, and most other invertebrate phyla • Exoskeleton – Hard segments cover muscles – Found in Arthropoda • Endoskeleton – Internal, contains bones and cartilage – Found in Chordata Types of Bones • Long Bones – Work as levers • Short Bones – Cube-shaped – In wrists and ankles • Flat Bones – Protect organs – Broad, have muscles attached • Irregular Bones Divisions of Human Skeleton • Axial Skeleton – – – – • Appendicular Skeleton Skull Sternum Ribs Vertebral Column – Shoulder Girdle – Pelvic Girdle – Extremities Types of Muscle • Skeletal Muscle – Voluntary movement – Example: Biceps • Smooth Muscle – Involuntary contraction – Used in digestion • Cardiac Muscle – Located in the heart – Pumps blood through the body http://faculty.etsu.edu/forsman/Histologyof muscleforweb.htm Interdependence • Skeletal muscle is directly controlled by the nervous system – Motor neurons are attached to muscle at neuromuscular junctions • B cells for the immune system are produced in bone marrow • Eyes use muscles to move • Digestion and Excretion use smooth muscles to transport the food Diseases and Disorders • Duchenne Muscular Dystrophy – Afflicts skeletal muscle – Person cannot create dystrophin – Muscle cells break down – X-linked genetic disorder • Cardiomyopathy – Afflicts cardiac muscle – Lower chambers of the heart weaken first • Osteosarcoma – Type of cancer – Mostly develops in bones near the knee Bone Cells • Osteoblasts – Create bone – 10 microns diameter – Derived from mesenchymal stem cell • Osteoclasts – Absorb bone – 20-100 microns diameter – Derived from macrophages • Osteocytes – Osteoblasts encased in bone matrix Bone: Connective Tissue Example of Skeletal Muscle -Connects muscle to bone -Connect bones Myofibrils • A fiber bundle contains hundreds of myofibrils that run the length of the fiber • Each myofibril is a linear array of sarcomeres • Each sarcomere is capped on ends by a transverse tubule (t-tubule) that is an extension of sarcolemmal membrane • Surfaces of sarcomeres are covered by SR Muscle Contraction Muscle Contraction in Action http://www.sci.sdsu.edu/movies/actin_myosin.html http://www.dnatube.com/video/1306/Muscle-contraction Works Cited • • • • • • • • http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookMUSSK EL.html http://kidshealth.org/teen/diseases_conditions http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&p ubmedid=17158703#id358647 http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&p ubmedid=10677457 http://www.sci.sdsu.edu/movies/actin_myosin.html http://www.mnsu.edu/emuseum/biology/humananatomy/skeletal/ske letalsystem.html http://www.engin.umich.edu/class/bme456/bonephys/bonephys.htm Garrett and Gershom. Biochemistry.