Cardiac and Smooth Muscle S1M2

  1. Cardiac muscle is derived from
    Splanchnic Mesoderm
  2. What are the only places that cardiac muscle are found
    In the heart and the roots of large vessels that join the heart
  3. Each cardiac cell contains how many nuclei
    One or two, never three
  4. What are some unique features in cardiac muscle cells that differentiate them from skeletal muscles
    • Intercalating discs
    • Lots of large mitochondria
    • Stair stack configuration between adjacent cells
    • Diad instead of Triad
    • Small terminal cisternae
    • Large T tubules
    • SR not well developed
  5. In cardiac muscle, how are the sarcomeres attached to one another
    • The transverse portion includes Zonula adherens and macula adherens (Desmosomes)
    • The longitudinal portion has Gap Junctions for communication
  6. Where are the diads located in relation to the sarcomere
    In the vicinity of the Z lines
  7. Calcium supply in cardiac muscle is different form skeletal muscles how
    It is supplied by the extracellular matrix
  8. How do cardiac muscles create their own spontaneous rythmic contraction
    By cardiac conducting cells like SA and VA nodes and fibers called purkinje fibers.
  9. Purkinje fibers store lots of
  10. Sympathetic and parasympathetic fibers terminating at the AV and SA nodes only do what
    Modify the rate of the intrinsic cardiac muscle contraction
  11. What is considered the pace maker of the heart
    SA node located in the superior vena cava
  12. Where is the AV node located
    In the AV septum
  13. What are cardiac endocrine cells
    Specialized cells that produce small peptide hormones, located in the atrial wall
  14. What is one of the Cardiac endocrine hormones and its function
    Atrial Natriuretic polypeptide, It decreases blood pressure by triggering the kidneys to make more urine
  15. Cardiac muscle cells can't regenerate, so when they die they
    Are replace by connective tissue
  16. Smooth muscle lacks what features compared to skeletal and cardiac muscle
    • No T tubules
    • No cross striations
    • No sarcomere
    • No Troponin
    • No myofibrils
  17. Smooth muscle cells have how many nucleus's and what shape
    • One nucleus centrally located
    • Spindle shape with no branches
  18. How is the myosin different in the smooth muscle
    They are all pointing the same direction
  19. Thin filaments in smooth muscle contain
    Actin and tropomyosin but NO troponin
  20. Myofilaments are arranged in smooth muscle how
    They criss cross obliquely forming a latticework and are attached to dense bodies (on cytoplasmic side)
  21. The psuedo Z lines in the smooth muscle are
    Dense bodies (serve as insertion points for myofilaments and intermediate filaments)
  22. Caveolae in Smooth muscle (sarcolemmal vesicles) serve what purpose
    May associate with sparse SR and may function in the release and sequestering of Ca++
  23. What does the inactive state of a smooth muscle myosin look like
    It is twisted in a circle
  24. Smooth muscle doesn't have what rule
    The all or none rule
  25. How does the contraction of smooth muscle work
    • CA++ is released from caveolae
    • Ca++ bind to Calmodulin
    • Calmodulin Ca++ complex activates the myosin light chain kinase
    • Actin binds (S1) to the unmasked myosin and contract
  26. When a hormone like Oxytocin is given to a female what happens
    This activates the myosin light chains in the uterus creating contractions inducing labor
  27. What are the two different types of smooth muscle cells
    • Multiunit
    • Visceral (Unitary Smooth muscle)
  28. Multiunit smooth muscle has what characteristics
    • They are richly innervated (each cell recieves inn.)
    • They are specialized for precise, graded conduction
    • Found in the iris of the eye, vas deferans
  29. Visceral smooth muscle has what characteristics
    • Minimal innervation
    • Few neuromuscular junctions
    • Impulses transmitted via nexus
    • Regulated by hormones (oxytocin) and stretching
    • Found in hollow organs (uterus, intestinal wall, ect.)
  30. Smooth muscle cells can do what, that other muscle cells can't
    Regenerate through mitosis, as well as arise from mesenchyme or pericytes
  31. What are two contractile non muscle cells
    • Myoepithelial
    • Myofibroblasts, used to close wounds
  32. Myoendothelium are most similar to what muscle and why
    Smooth muscle, they have only actin and myosin, the contraction is similar to smooth muscle, they are activated by Oxytocin, and are calmodulin mediated
  33. What are the two main ways to distinguise between muscle cells
    The presence of striations and the position of the nucleus
  34. Myoepithelial cells arise from
  35. Myoepithelial cells are associated with
    Glandular secretory units (basket shaped)
Card Set
Cardiac and Smooth Muscle S1M2