BIOL 404-Exam 4-Muscle 13

  1. What are the five major causes of contractile activity in smooth muscle?
    • Spontaneous electrical signal
    • neurotransmitters
    • hormones
    • Local chemical changes
    • Stretch
  2. What is a Single Unit smooth muscle?
    Smooth muscle cells that are connected by gap junctions and respond simultaneously
  3. What is the term for smooth muscle that is connected by gap junctions and all cells involved respond simultaneously?
    A Single-unit
  4. What is the term for a group of smooth muscle cells that respond to stimuli independently and contain few gap junctions?
    Multi-Unit smooth muscle
  5. What is multi-unit smooth muscle?
    A group of smooth muscle cells that act independently due to few gap junctions
  6. How many nuclei do cardiac muscle cells contain?
    1 or 2
  7. Where are nuclei in cardiac muscle cells located?
  8. Are cardiac muscle striated?
  9. What mechanism do cardiac cells use to contract?
    Sliding filament mechanism
  10. What is a critical feature to maintain electrical coupling in cardiac muscle?
    Gap Junctions
  11. Describe teh morphology of cardiac muscle cells?
    • 1 to 2 centrally located nuclei
    • branching
    • intercalated discs
    • Desmosome
    • Gap junctions
    • large mitochondria
  12. What is the absolute refractory period for cardiac muscle?
    250 ms
  13. What is Automaticity or Autorhythmicity?
    Ability for a muscle fiber to stimulate its own action potential
  14. What cells in cardiac tissue have automaticity?
    The node cells
  15. Why does the heart have an absolute refractory period of 250 ms?
    To prevent tetanic contraction
  16. What are intercalated discs?
    Interlocking finger like ends of cardiac muscle that bind neighboring muscle cells
  17. What are desmosomes?
    Locking plates within the Cardiac muscle intercalated discs
  18. Describe the flow of excitation contraction coupling in cardiac muscle:
    • depolarization
    • opening of L-type Ca channels in the T-tubules
    • Ca flows into cytosol
    • Ca binds Ryanodine receptors
    • Ca flows from SR to cytosol
    • Contraction
  19. Describe a cardiac muscle action potential:
    A fast depolarization followed by slow repolarization
Card Set
BIOL 404-Exam 4-Muscle 13
BIOL 404-Exam 4-Muscle 13