Histo Lecture 1

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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

Card Set Information

Histo Lecture 1
2011-01-31 00:36:20

Intro to Heart
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