Week 3 Material

Cards (52)

  • What are the 3 types of muscle cells?

    skeletal, cardiac, smooth
  • Which muscle type has the largest diameter?

    Skeletal
  • Which muscle type has the longest length?

    Smooth
  • Which muscle type is multinucleated?

    Skeletal
  • Which nervous system controls skeletal muscle?
    somatic nervous system (voluntary)
  • Motor neurons
    Cell body in spinal cord or brain stem
    each one can innervate multiple muscle cells
    acetylcholine is neurotransmitter
  • neuromuscular junction
    only 1 synapse per muscle cell (fiber)
    always excitatory
    usually, one synaptic event will provoke action potential in the muscle fiber
  • End plate potential
    a single firing of the motor neuron will cause a local graded potential
  • Muscle fibers
    composed of multiple myofibrils that extend the length of the muscle fiber
  • Myofibrils
    bundles of contractile proteins
  • When does muscles contract?
    When myofibrils shorten
  • Sarcomere
    consists of a bundle of myofibrils extending from one Z line to the next and composed of overlapping actin and myosin filaments
  • I band

    actin filaments only
  • A band
    region of overlapping myosin and actin filaments
  • H band

    zone within A-band where myosin filaments don't overlap with actin
  • Z line
    line separating two neighboring sarcomeres
    made up primarily of alpha actinin
  • What protein makes up the Z line
    alpha-actinin
  • M line
    band of connections between myosin filaments
    primary protein is myomesin
  • What protein makes up the M line
    myomesin
  • Contraction in sarcomere
    sliding of actin over myosin which shortens structure
  • Titin
    elastic protein which extends from the Z line to the M line and is linked to the myosin filaments to keep them centered
  • Nebulin
    Is associated with the actin filaments and is essential for regulating thin filament length
  • Dystrophin
    links actin to the extracellular matrix and is a large X-linked protein
  • Duschenne Muscular Dystrophy
    Individuals homozygous for loss of functional alleles of dystrophin
    Cell membranes of muscle fibers become damaged and leaky, leading to death of muscle cells and weakened skeletal muscles
  • Myasthenia gravis
    Cause: autoantibodies to nicotinic AChRs
    Symptoms: Skeletal muscle weakness
    Treatment: Immunosuppressant drugs
  • Spinal muscular atrophy (SMA)

    Cause: mutations in SMN1 gene
    Symptoms: skeletal muscle weakness and atrophy
    Treatments: Antisense RNA, gene therapy, and enhanced expression of full length SMN2 protein
  • Rigor configuration
    Starting position of muscle contraction cycle; myosin is bound tightly to actin
  • Role of Ca2+ in skeletal muscle contraction
    Ca2+ binds to troponin → shifts tropomysoin → exposes myosin binding site → muscle contraction
  • Where is calcium stored
    sarcoplasmic reticulum
  • how is calcium released from sarcoplasmic reticulum?
    interaction of two receptors (DHP receptor and Ryanodine receptor)
  • What are the mechanics of single-fiber contraction?
    isometric contraction and isotonic contraction
  • isometric contraction
    Length of muscle stays the same but change in tension
  • isotonic contraction
    tension stays the same but change in length
  • What are the two types of isotonic contraction?

    concentric contraction and eccentric contraction
  • Concentric contraction
    type of isotonic contraction where tension exceeds load and causes muscle to shorten
  • Eccentric contraction
    type of isotonic contraction where load exceeds tension and causes muscle to be stretched out
  • Fatigue from short term exercise

    lactic acid build up
    ATP depletion
  • Fatigue from long term exercise

    ryanodyne R leakage
    Glycogen depletion
    Central command fatigue
  • What are the three types of muscle fibers?
    slow oxidative fibers, fast oxidative-glycolytic fibers, and fast glycolytic fibers
  • primary source of atp production in slow oxidative fibers
    oxidative phosphorylation