physiology

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Author:
stkychic
ID:
48495
Filename:
physiology
Updated:
2010-11-09 14:58:28
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cardiac function
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Description:
chapter 13 exam 5
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  1. Define myogenic
    myogenic means the cardiac muscle of the heart has the ability to contract without signals from the nervous system, it gets signals from within the cardiac muscle itself.
  2. define autorhythmicity
    the ability of the heart to generate signals that trigger its contractions on a periodic basis-that is, to generate its own rhythm.
  3. what are autorhythmic cells, and what do they do?
    Autorhythmic cells are a small precentage of the cardiac muscle cells. they generate little or no contracticle force, but are critical to hte hearts pumping action because they coordinate and provide rhythm to the heartbeat.
  4. define contracticle cells of the heart
    they are the cells that generate contracticle force. the cells that do the actual beating of the heart
  5. what are pacemaker cells
    pacemaker cells initiate the contractions of the heart. They generate spontaneous action potentials. They determine the rate or pace of the heartbeat by firing action potentials on a regular basis.

    They are located in nearly all parts of the heart, but concentrated in the sinoatrial node (SA Node) and the (AV Node) atrioventricular node.
  6. What are the conduction fibers?
    Conduction fibers are specialized to quickly conduct the action potentials generated by the pacemaker cells from place to place through the myocardium.
  7. describe the components of the intercalated disks
    Gap junctions and desmosomes
  8. describe the function of the gap junctions within the intercalated disks of the heart
    all cardiac muscle cells are connected to their neighbors by gap junctions, which permit electrical current to pass in the form of ions from one cell to another.
  9. what is the role of the desmosomes
    they are areas in which protien fibers lik adjacent cells together, forming a physical bond between them that resists mechanical stress. important to resist stretching that occurs every time heart fills with blood

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