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– Skull– Sternum– Ribs– Vertebral Column

• Appendicular Skeleton– 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/Histologyofmuscleforweb.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 Actionhttp://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&pubmedid=17158703#id358647• http://www.pubmedcentral.nih.gov/articlerender.fcgi?

tool=pubmed&pubmedid=10677457• http://www.sci.sdsu.edu/movies/actin_myosin.html• http://www.mnsu.edu/emuseum/biology/humananatomy/skeletal/

skeletalsystem.html• http://www.engin.umich.edu/class/bme456/bonephys/bonephys.htm• Garrett and Gershom. Biochemistry.