Cardiac and Smooth muscle S1M3

  1. The heart is induced by what to create an action potential
    Calcium and in turn releases calcium
  2. What are the three main phases of the slow response pacemaker action potential
    • Depolarization (Ca+ influx from slow L-type channels)
    • Repolarization (Close L-type Ca+, Efflux K+)
    • Pacemaker potential ie. slow depolarization (K+ closure, Funny (If) Na+ influx, 2 Ca+ influx (L and T) open)
  3. The slow response pacemaker action potentials happen in what muscles
    Cardiac and Smooth
  4. What are the series of events for the Fast response ventricular/atrial action potentials
    • Depolarization (Fast voltage gated Na+ In)
    • Early repolarization (K+ exit, Na+ inactivate)
    • Plateau phase (Open L-type Ca+ In, delayed K+ Out)
    • Rapid Repolarization (K+ exit faster than Ca+ enter)
    • Resting membrane potential (K+ exits to maintain resting state)
  5. Efflux means what
    Process of flowing out
  6. Ca+ T type is only used in what action potential
    In the slow response pacemaker action potential
  7. What is the binding protein on the SR in Cardiac muscle holding in Ca+ that is not found in skeletal muscle
  8. What are the three ways that cardiac muscle removes Ca+ after an action potential
    • SERCA Pump
    • Ca ATPase pump on the plasma membrane
    • Na-Ca+ pump on the plasma membrane
  9. How are the RyR and DHPR proteins different in the cardiac muscle
    They are not physically bound like in skeletal
  10. What is SERCA
    Sarcoplasmic Reticulum ATPase pump located on skeletal, cardiac, and smooth muscle
  11. What is EC coupling
    Excitation contraction coupling
  12. Cardiac muscle action potentials duration compare how to skeletal muscle potentials
    They are longer
  13. What is responsible for the automated depolarization in a pacemaker action potential
    Funny Na+ channels influx
  14. What are the four pumps on the cardiac muscle plasma membrane and what do they do
    • Ca ATPase (Pump CA out)
    • Na-Ca Pump (3Na in and 1Ca out)
    • NaK ATPase (3Na out 2K in)
    • Na-Hx (H out Na in)
  15. What is required on the outside of the cell of cardiac that is not required in skeletal
  16. Primary Na+/K+ pumps create an environment that is necessary for what
    High Na+ on the outside of the cell that the secondary active Na+/Ca+ uses to remove Ca+ after an action potential
  17. The heart relies solely on what metabolism
    Aerobic metabolism through oxidative phosphorylation, this is what provides the essential ATP
  18. In what actions is the ATP used in cardiac muscle
    • To pump Ca+ out of the cell
    • To pump Ca+ into the SR
    • To pump Na+ out and K+ into the cell
  19. Because of the length of a cardiac muscle action potential, what results
    There is a mandatory absolute refractory period that the heart uses to fill its ventricles, therefore there is no tetanic action in in the cardiac
  20. Why is it called passive tension
    It doesn't require ATP to achieve it
  21. What makes the heart have a passive tension that increases further then in skeletal muscle
    It has a lot of connective tissue
  22. What are the two groups that smooth muscle can be divided into
    • Single unit muscle (Gap junctions)
    • Multiunit muscle (No/few gap junctions)
  23. What are the four different states of smooth muscle contraction
    • Normally contracted
    • Normally partially contracted
    • Phasically active
    • Relaxed
  24. What are the different ways that a smooth muscle can be triggered
    • Hormones/Autonomic nervous system
    • Local changes in extracellular fluid
    • Pacemaker cell
    • Stretch
  25. What are the different mechanisms for Ca+ entry into smooth muscle
    • Receptor activated channel
    • Voltage dependent Ca++ channel (Act. RyR on SR)
    • G-Protein coupled receptor (Act. IP3 on SR)
  26. What is the series of events leading to muscle contraction in smooth muscle
    • Calcium binds Calmodulin
    • Ca-Calmodulin binds MLCK
    • MLCK uses ATP to phosphorylate myosin
    • Myosin binds to actin
    • Myosin is dephosphorylated by MLCP
  27. Where is ATP required in the smooth muscle
    • Ca+ pump out of the cell
    • Ca+ pump out of SR
    • Na+/K+ pump out of the cell
  28. Why does smooth muscle stay contracted for so long
    The dephosphorylation of the myosin takes much longer
  29. What makes the smooth muscle more efficient when it comes to the use of ATP
    They can stay contracted, therefore the ATP is not needed for the release of the myosin
  30. Why in the smooth muscle length verse tension diagram is the passive tension started so much earlier, and the active tension so broad
    The actin myosin spans the whole cell, this gives it more mysoin and actin to bind
  31. Beta receptors like epinephrine and norepinephrine have what affect on the cardiac muscle
    Increase the conversion of ATP to cyclic AMP, the cAMP increases the Ca through L receptors into the SR for subsequent release.
  32. What are the primary metabolic substrates used by the heart
    Lactate and fatty acids
  33. What does the drug digitalis do to the heart
    It inhibits the Na-K ATPase pump increasing the amount of Ca+ in the cell in turn increasing contractility
  34. Single unit smooth muscle has what type of action potential
    Pacemaker action potential
  35. Multi unit smooth muscle cells are often found where
    lung airways, large blood vessels, eye muscles, and hair follicles.
  36. What are the three different ways that Ca enters smooth muscle
    • Voltage activated Ca channels
    • Receptor activated channel (Ligand)
    • G- Protein coupled receptor (Chemical signals like hromones)
  37. How does a G protein receptor activate Ca+ release
    It triggers the production of IP3 in the cell which stimulates Ca+ release from the SR
Card Set
Cardiac and Smooth muscle S1M3