The Muscular System

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