Intro to Physio

  1. what is the neuromuscular junction?
    region where a motor neuron communicates with a skeletal musle fiber
  2. how does the acetylcholine (ACh) cross to the sarcolemma?
    • axon terminal of the neuron vesicles filled with ACh can cross the synaptic cleft to bind to receptors on the sarcolemma
    • ACh binds to receptor on the motor end plate. 
    • Neurons stimulate sarcolemma by generating an action potential
    • AChE breaks down ACh thus inactivating the signal
  3. what is calsequestrin?
    special protein filaments that sequester Ca2+ in bunches inside SR
  4. how is calcium stored and released?
    • calcium ion pumps in the SR pulls Ca+2 in
    • calsequestrin sequester Ca+2 in bunches
    • when stimulated, Ca+2 channels open, releasing flood of Ca+2
    • Ca+2 channels relcose instantly and Ca+2 is pumped back into SR
  5. what happens when sarcomeres contract? 
    • so does th entire muscle fiber
    • as fibers contract, tension is created by tendons pulling on bones
  6. how does movement occur?
    when tension is greater than the resistance
  7. how does variation in tension occur?
    • amount of overlap of the myofilaments
    • frequency of stimulation
  8. what is the maximal strength that a muscle can develop directly related to? 
    initianl length of its fibers
  9. define a muscle twitch
    a single stimulus-contraction-relaxation cycle in a muscle fiber or whole muscle
  10. what happens in the latent period of muscle twitch?
    includes the action potential, release of Ca2+, activitation of troponin/tropomyosin
  11. describe the contraction phase
    development of tension b.c of the cross-bridge cycle of mysosin and actin
  12. what happens in the relaxation period?
    tension decreases due to the restorage of Ca2+ and covering of actin active sites
  13. wave summation
    repeated, frequent stimuli that tirgger a response before full relaxtion has occured
  14. incomplete tetanus
    near peak tension with little relaxation, while complete tetanus occurs when stimuli are so frequent that relaxtion does not occur
  15. treppe?
    gradual increase in muscular contraction following rapidly repeated stimulation
  16. why is the initial contraction weaker than subsequent?
    • increase in ca+2 within sarcoplasm, so more active sites exposed, more cross-bridgin gof actin-myosin
    • neural component: more moto units firing
  17. what is a motor unit?
    a single motor neuron and all the muscle fibers it innervates
  18. what are two types of motor unit?
    • fine control movement: use motor units with very few fibers per neuron
    • gross movements: use motor units have a high fiber-to-neuron ration
  19. how are motor units recruited?
    activiation of more and more units to produce adequate tension beginning with the small neurons first (smooth gradation of increasing strength)
  20. types of contraction?
    • isotonic
    • isometric
  21. what is isotonic muscle contraction?
    when the length of the muscle changes, but the tension remains the same until relaxation
  22. what is isometric contraction?
    when the whole muscle length stays the same, the tension produced does not exceed the load
  23. elongation of muscle after contraction passively uses a combination of what?
    gravity, elastic forces, oposing muscle movement
  24. what happens to glucose and fatty acids as being catabolized
    ATP produced to used to power contractions
  25. what are the products for lactic acid fermentation?
    • pyruvate reduced to lactate and NADH oxidzed to NAD+
    • lactate is carrie by the blood to theliver, whiere it is converted to another time
  26. energy sources of skeletal muscle during work?
    • ATP
    • creatine phosphate
    • anaerobic
    • aerobic glycolysis
Card Set
Intro to Physio