RHYTHMICAL EXCITATION OF THE HEAT

The heart has a special system for self-excitation of rhythmical impulses to cause repetitive contraction of the heart. This system conducts impulses throughout the heart and causes the atria to contract one sixth of a second before the ventricles contract, affording extra filling of the ventricles with blood before contraction.

The parts of the rhythmical conduction system and their function are as follows:

• Sinus node (or the sinoatrial node), which initiates the cardiac impulse

• Internodal pathway, which conducts impulses from the sinus node to the atrioventricular (A-V) node

• A-V node, which delays impulses from the atria to the ventricles

• A-V bundle, which delays impulses and conducts impulses from the A-V node to the ventricles.Right and left bundles of Purkinje fibers, which con­duct impulses to all parts of the ventricles.

After the end of the lesson students will be able to learn about:

  • Specialized excitatory and conductive system of the heart.
  • Control excitation and conduction in the heart.
  • Sympathatic and Parasympathatic Nerves control Heart Rhythmicity and Impulse conduction by the Cardiac Nerves. 

 

 

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