Histo Lecture 1

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Histo Lecture 1
2011-01-30 19:36:20

Intro to Heart
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  1. What are intercalated discs?
    • -Junction between adjacent myocardial cells
    • -Contain gap junctions for easy ionic conductance
  2. Mitochondria make up how much of the sarcoplasm?
  3. What is the major fuel for cardiac cells?
    • Fatty acids
    • Minimal amount of glycogen present
  4. Myocytes are connected by what?
    Gap junctions
  5. What do gap junctions allow in the heart?
    • Ionic conductance between cells
    • Allows syncytium
  6. What are the five differences between cardiac and skeletal muscle?
    • Gap junctions
    • Intercalated discs
    • Single nucleus
    • Less developed SR and T-tubules
    • Autonomic innervation
  7. Define syncytium
    • Multinucleate mass of cytoplasm resulting from the fusion of cells
    • -Depolarization travels as a "wave" throughout the myocardium
    • -Impulse to one area of heart results in contraction of entire myocardium
  8. Syncytia portions (atria/ventricles) are separated by what?
    The fibrous "ring" tissue surrounding the AV valves
  9. Fibrous ring prevents what?
    • Conduction of impulse from atria to ventricles
    • -Allows atria and ventricles to contract separately
  10. A plateau in an action potential is cause by what?
    "Slow" calcium channels that remain open longer than sodium channels
  11. Why is there a delayed repolarization period in cardiac muscle?
    Caused by delayed movement of K+ out of cell
  12. What is Systole?
    • Ventricular contraction
    • Heart ejects blood into pulmonary and systemic circulation
  13. What is Diastole?
    • Ventricular relaxation
    • Atria and ventricles fill with blood
  14. What is mean arterial blood pressure (MABP)?
    Average pressure exerted by the blood against the walls of systemic arteries