Part 4: ANS, Muscle Fatigue, Sarcopenia Flashcards Preview

SF1.12 Muscle Physiology (ZACHOW) > Part 4: ANS, Muscle Fatigue, Sarcopenia > Flashcards

Flashcards in Part 4: ANS, Muscle Fatigue, Sarcopenia Deck (12)
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The sympathetic nervous system utilizes what two neurotransmitters?

  • epinephrine and norepinephrine
  • bind to type alpha and type b receptors


Type beta adrenergic receptors:

  • expressed in skeletal muscle
  • bind epinephrine and/or norepinephrine released from sympathetic nervous system
  • stimulate muscle anabolism and repair


Glucocorticoids (cortisol and its derivatives) are released as part of: 

  • immune/anti-inflammatory responses
  • stress-induced secretion


Glucocorticoids (cortisol and its derivatives) are released from:

  • adrenal cortex (sits on top of kidney)


Effect of glucocorticoids (cortisol and its derivatives):

  • Proteolytic effects:
    • type II fiber atrophy
    • myostatin elevation (blocks satellite cell mitosis)
    • inhibition of IGF-1


What is the goal of glucorticoid activation and its subsequent binding to glucocorticoid receptors?

  • to maintain blood glucose levels


The two components of muscle fatigue:

  • central nervous system
  • muscle tissue


How does the CNS influence muscle fatigue?

  • release of serotonin and cytokines


What is the main reason for muscle fatigue?

inhibition of cross-bridge cycling via:

  • proton accumulation
  • potassium efflux from T-tubules 
  • decreased glycogen stores
  • free radicals, superoxides, ROS


Anaerobic metabolism leads to an increase in protons in muscle tissue. What does this effect?

  • reduces development of tetanic force
  • type II muscle fibers most effected
  • no effect on rate of fatigability



  • a physiologic decrease in muscle strength that occur with age
  • type II muscle fibers (fast-twitch) primarily effected
  • due to a decrease in growth hormones and anabolic androgens


The process of sarcopenia begins at what age?

  • sometime around age 30 years, after which muscle loss can approach 3-8% per decade.