Anatomy final

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  1. 3 Major types skeletal muscle fibers
    • fast fibers
    • slow fibers
    • intermediate fibers
  2. qualities of fast fibers
    • reach peak twitch tension in .01 sec or less after stimulation
    • large in diameter
    • contain densely packed myofibrils, large glycogen reserves, few mitochondria
    • fatigue easily because contractions require large amount of ATP. too few mitochondria to generate enough ATP
  3. qualities of slow fibers
    • half size in diameter compared to fast fibers
    • 3 times as long to reach peak tension
    • high oxygen supply to support mitochondria activity
    • continues contracting after fast fibers become fatigued
  4. qualities of intermediate fibers
    • relatively pale, contain little myoglobin
    • intermediate capillary network and mitochondrial supply
    • more resistant to fatigue than fast fibers
  5. What is muscle hypertrophy?
    • enlargement of stimulated muscle
    • muscle fibers grow in diameter
    • occurs in muscles that have been repeatedly stimulated to produce near maximal tension
    • increases amount of tension produced when muscles contract
    • Increasing amount of protein synthesis to increase number of myofibrils·         
    • Muscle cells do not like to divide (except epithelia so that way it could repair itself when damaged)
  6. what is muscle atrophy?
    • reduction in muscle size, tone, and power
    • in extreme atrophy, results are permanent (why physical therapy is important)
    • Decrease in number of myofibrils
    • When proteins are replaced by fibrous (connective) tissue, you cannot make the muscle large again  
    • Really bad atrophy is usually a problem from the central nervous system
    • Polio: virus that attacks motor neurons so it cannot stimulate muscle
  7. what is ATP?
    • adenosine triphosphate
    • high energy compound used by cells
    • 2 phosphate groups attached to nucleotide, adenosine monosphate connected by high energy bonds incorporating energy released by catabolism
  8. What is CP/ how is it formed?
    • CP= creatine phosphate
    • high energy compound
    • at rest, skeletal fibers produce more ATP than it needs, ATP transfers energy to creatine (small molecule muscles assemble from fragments of amino acids)
    • energy transfer creates CP
  9. What occurs during muscle fatigue?
    • depletion of metabolic reserves within muscle fibers
    • damage to sarcolemma and sarcoplasmic reticulum
    • decline in pH within muscle fibers which decreases calcium ion bonding to troponin and alters enzyme activity
    • sense of weariness, reduction in desire to continue activity
  10. Components involved in muscle contraction
    • calcium--> triggers reaction that allow actin and myosin to attach and cause a contraction
    • troponin chances shape when calcium bonds to it
    • change in shape of troponin causes tropomyosin to become pulled, uncovers binding sites on actin for myosin
  11. steps in muscle relaxation
    • not enough action potentials arriving in the neuromuscular junction to continually release Ach to maintain contraction
    • calciu concentrations in sarcoplasm return to normal resting levels
    • active calcium transport across sarcolemma into extracellular fluid
    • active calcium transport into sarcoplasmic reticulum 
    • once calcium concentrations fall:
    • calcium ions detach from troponin, troponin returns to original orientation, active sites on actin are covered by tropomyosin
  12. what is a twitch?
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Anatomy final
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