Cardiac Muscle

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  1. Is cardiac muscle striated or non-striated?
  2. Is cardiac muscle under voluntary or involuntary control?
  3. What nervous system regulates cardiac muscle?
    Autonomic nervous system
  4. What are pacemaker cells and where are they found in the heart?
    Pacemaker cells are small, pale and with few organelles and thick and thin filaments.  They drive the electrical activity of the heart (where the heartbeat originates).  They are found at the sinoatrial node and atrioventicular node.
  5. What are conductor cells and where are they found in the heart?
    Conductors are short, broad, oriented end to end with few lateral connections.  They are insulated on the outside and have gap junctions which allows electrical signals to pass from cell to cell.  They are found at the Bundle of His and Purkinje Fibres.
  6. What are contractile myocardial cells and where are they found in the heart?
    Contractile myocardial cells give the heart muscle its striated appearance as they contain lots of thick and thin filaments.  They make up the walls of the ventricles and atria.
  7. Describe a contraction of the heart
    • An action potential starts at the sinoatrial node.  The wave of excitation spreads over the atria (the electrical signal passes through gap junctions between cells) and causes depolarisation of the atrioventicular node.  The action potential set up at the AN node passes to the Bundle of His down to the apex of the heart, along the Purkinje fibres and to the cardiac cells that make up the ventricles.  
    • The Bundle of His delays the contraction of the ventricles till after the contraction of the atria.  This is essential to have an effective pump system.
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Cardiac Muscle
2013-12-29 20:18:51
Cardiac Muscle

Module 1 - Baseline Body Systems - Cardiac Muscle
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