The Muscular System
Jan 22, 2016
The Muscular System
Muscle Types
http://www.nsbri.org/HumanPhysSpace/
Skeletal Muscles
• Striated• Bundles of
myofibrils• Sarcomeres,
along length of fibers
• Responsible for voluntary movement
Bicep and Tricep
Cardiac muscles
• Striated• Fibers branch &
interconnect via intercalated discs
• Discs – relay signals from cell to cell during heartbeat (synchronize)
• Forms contractile wall of heart
Cardiac muscle – Bio 162 archive
Cardiac Muscle
Smooth muscle• Spindle-shaped cells • Lacks striations• Contracts more slowly• Remain contracted longer• Controlled by different
nerves than skeletal• Involuntary body activities• Found in: walls of
digestive tract (churning), urinary bladder, arteries (constriction), and other internal organs
Cat Throat
Human Muscle Contraction
• Step 1: Myosin heads attach to binding sites on the actin filaments
• Step 2: Myosin heads move to the center of the sarcomere, remove themselves, then reattach to actin filament
• This cycle occurs hundreds of times per second during muscle contraction
Courtesy of SDSU Dept. of BiologyCourtesy of SDSU Dept. of Biology
Muscle Contraction
Jellyfish
• Do not have much control over which direction they will move in
• Create a jet propulsion effect to push themselves along
• Have a bell-shaped section on their body, which they fill with H2O and then release the H2O from beneath
Clam• Have a muscular
foot which aides in its movement
• Muscualr foot balances from the front to the back in a wavelike motion, helping the clam move
http://images.google.com/imgres?imgurl=www.assateague.com/clam-dia.gif&imgrefurl=http://www.assateague.com/nt-bival.html&h=206&w=300&sz=16&tbnid=Df8larSJLmgJ:&tbnh=76&tbnw=110&prev=/images%3Fq%3Dclam%26hl%3Den%26lr%3D%26ie%3DUTF-8%26oe%3DUTF-8
Starfish
• Use a water-vascular system and their tube feet to move
• H2O moves in and out of their feet, altering the pressure of the water and releasing suction, which helps the starfish move along rocks
Lancelet Branchiostoma• Swim by lateral
undulations of the body
• Undulations are caused by contractions of the axial musculature
• Move in a side to side motion that is similar to swimming
http://images.google.com/imgres?imgurl=library.thinkquest.org/C006669/media/Biol/img/lancelet.gif&imgrefurl=http://library.thinkquest.org/C006669/data/Biol/chord_2.html&h=425&w=400&sz=33&tbnid=paT0_yBZBFYJ:&tbnh=121&tbnw=114&prev=/images%3Fq%3Dlancelet%26hl%3Den%26lr%3D%26ie%3DUTF-8%26oe%3DUTF-8%26sa%3DG
Grasshopper
• Exoskeleton, hard segments, which cover the muscles and visceral organs
• Muscles attach to the inner surface of exoskeleton
Bony Fish
• Contains muscles in the tail and trunk which are made of myotomes, also known as muscle blocks
• Myotomes are separated by connective tissue called myosepta
• The fins are made up of abductor muscles which open the jaw and adductor muscles which close the jaw
• These muscles move the fins away and toward the body
Birds
• Pectoral muscles move wings
• Pectoral muscles are attached to the keel in order for the wings to spread
Frogs
• Voluntary muscles are present which the frog has control over
• These muscles occur in combinations of flexors and extensors
• Flexor contracts and bends
• Extensor contracts and straightens
http://images.google.com/imgres?imgurl=www.vrealities.com/frog2.jpg&imgrefurl=http://www.vrealities.com/education.html&h=209&w=275&sz=11&tbnid=xxwpZzW_jtUJ:&tbnh=82&tbnw=107&prev=/images%3Fq%3Dfrog%2Bdissection%26hl%3Den%26lr%3D%26ie%3DUTF-8%26oe%3DUTF-8
Sharks• Various skeletal muscles, in particular branchiomeric, smooth and cardiac muscles
• The branchiomeric muscles undergo the most evolutionary change
• Branchiomeric muscles are striated, attached to bone, form head muscles, and neck muscles
• Differences would be; skeletal somatic muscles and skeletal visceral muscles
• Skeletal somatic muscles deal with locomotion and develop from the myotome of epimere and somatic layer of hypomere
• Skeletal visceral muscles deal with respiration and feeding and develop from the neural crest cells
Human• Skeletal muscle is
controlled by the nervous system– contractions are mainly
automatic• Cardiac Muscle contracts
by the sliding filament method– Forms branching fibers
• Smooth Muscle is controlled by the nervous system and hormones– Involuntary muscles
because we are unable to control them
Sites
• http://www.tiscali.co.uk/reference/encyclopaedia/hutchinson/m0007436.html
• http://quantum.plsweb.com/Common/QHomeSite/samplecourse/bio36_2.html
• http://ohs-bio.www1.50megs.com/Biology_Notes/Fish.htm#BF%20Nervous%20system
• http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookMUSSKEL.html
• http://www.flmnh.ufl.edu/fish/Education/Diagrams/FishBodyParts.htm