ch 11

what is the muscular system made of? name the diff types? what is muscle tissue and its characteristics? function?

700 skeletal muscles (voluntary) make up muscular system

• innervated by somatic motor neurons

muscle tissus

• skeletal, cardiac and smooth

• skeletal muscle cells are muscle fibers

• alll muscle tissue has muscle cells and

  • excitability (respond to stimuli)

  • conductivity (ransmit electrical events across membrane)

  • contractility (generate tension and shorten cell length)

  • elasticity (return to resting lenght after change)

  • extensibility (stretched beyond resting length)

• each skeletal muscle is considered an organ 

  • contain all tissue type (epithelial, connective, muscle, nervous)

  • striated

  • attached to bone 

  • cells and muscle vary in shape and sizes

• function

  • body movement, maintain posture, protect and support, regulate elimination of materials , produce heat

strucutral organization of skeletal muscle? what is fascia?

• muscle - multipple fascicles w a bundle of muscle fibers in them

  • epimysium ….dense irreg conn tissue

  • also has connective tissue coverings, blood vessels and nerve fibers 

• fascicle is a bundle of muscle fibers 

  • perimysium …dense irreg connect tissue w blood vessels and nerves

  • seperation of fibers is by dense irregular connective tissue

• muscle fibers (muscle cell) contain myofibrils (organelles)

  • endomysium (electrically insulates each fiber)…areolar connective tissue w reticular fibers  

  • elongated, multinucleating, cylindrical

  • myofibrils seperated w areolar connective tissue 

  • has striation

• mycrofibrils are filled with microfilaments 

  • thick filaments composed of myosin 

  • thin composed of actin, tropomyosin and troponin

deep fascia: large sheet external to epimysium

• surround each muscle bind muscle w similar function 

• dense irreg conn tissue w vessels and nerves 

superficial fascia: seperates muscle from skin 

• areolar and adipose conn tissue

muscle attachments

• tendon-attaches muscle to bone skin or another mucle

  • formed by merger of conn tissue at end of muscle

  • ropelike structure

  • aponeurosis is a thin flattened conn tiss attachment

• orgin

  • fixed/stable

  • proximal, medial, inferior, big

• insertion

  • less stable/movable,

  • distal, lateral, superior, small

what are axons? what are the three similar to a regular cell? what are t-tubules?

• axons pass through all three layers of conn tissue to form junctions w individual skeletal muscle fibers

• sarcolemma: plasma membrane 

• sarcoplasm: cytoplasm

• sarcoplasmic reticulum: smooth ER

  • internal membrane complex

  • stores calcium (used to initiate contraction)

  • includers terminal cisternae adjacent to t-tubules

    • triad=two terminal cisternae and one T-tubule

• tranverse tubules (T); deep invaginations osf sarcolemma that go into sarcoplasm 

  • carry impulses form sarcolemma to stimulate contraction

what are myofibrils 

• myofibrils: cylindrical w muscle fibers

  • run length of the cell

  • make 80%of fiber volume

  • ability to shorten, cause contraction

• contaim myofilaments: strands