Cardiac Muscle

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Across
  1. 1. The third wave is a dome-shaped upward deflection called the
  2. 4. Cardiac excitation normally begins here
  3. 8. The mechanism of contraction is similar in cardiac muscle is similar to ________ muscle
  4. 13. This is a period of maintained depolarization in contractile fibre
  5. 14. This is a small upward deflection on the ECG
  6. 15. This cell organelle is larger and more numerous in cardiac muscle fibers than in skeletal muscle fibers.
  7. 17. These large diameter fibres rapidly conduct the action potential beginning at the apex of the heart upward to the remainder of the ventricular myocardium
  8. 18. __________ Q wave may indicate a myocardial infarction
  9. 20. The instrument used to record the changes is called
  10. 21. The recovery of the resting membrane potential takes place during this phase of action potential
  11. 23. cardiac muscle has a smaller intracellular reserve of ______ ions
  12. 24. QRS complex begins with a ________ deflection
  13. 25. ECG involves measuring the time spans between waves called
  14. 27. The spontaneous depolarization in SA node is a ______ potential
  15. 28. AV bundle is also called as
  16. 29. The phase of relaxation.
Down
  1. 2. A recording of electrical signals is called
  2. 3. High blood K+ level causes
  3. 5. Intercalated discs contain these to hold the fibres and gap junctions together.
  4. 6. Larger P waves indicate enlargement of
  5. 7. irregular transverse thickenings of the sarcolemma are called
  6. 9. The SA node is a ______ pacemaker
  7. 10. First step in the action potential occurs of a contractile fiber
  8. 11. This sets the rhythm of electrical excitation that causes contraction of the heart.
  9. 12. The source of this electrical activity is a network of specialized cardiac muscle fibers called
  10. 16. the action potential travels along the conduction system and spreads out to excite these fibres
  11. 19. These allow the entire myocardium of the atria or the ventricles to contract as a single, coordinated unit.
  12. 21. In muscle, this period is the time interval during which a second contraction cannot be triggered
  13. 22. the phase of contraction
  14. 26. Number nuclei present in a muscle cell