Anatomy And Physiology Of The Cardiac Cycle Essays

805 Words Jun 17th, 2016 4 Pages
Jennifer Datus
Anatomy and Physiology II
Essay Questions Test 2
Professor Vernet

1. The beginning of the cardiac cycle starts with deoxygenated blood from the systemic circulation entering the heart into the right atrium from the superior and inferior vena cava. A chamber of the heart beats because of the electrical impulses located around areas of the heart that travel across the heart which allows the muscles to contract.The SA node located in the right atrium is also known as the pacemaker of the heart, this node conducts an electrical impulse that makes the right atrium contract causing the tricuspid valve to open and for blood to pass through into the right ventricle. Then when the right ventricle is ready to contract the tricuspid valve closes in order to prevent regurgitation. The AV node causes ventricular contraction so this node sends its impulse and the right ventricle contracts and the pulmonic valve opens, blood is pushed through this valve into the pulmonary artery and into the lungs in order to oxygenate the blood. But before this, the impulse travels along the Bundle of His which separates into two branches, the right and left bundle branches which lie in the septum.The branches spread into Purkinje fibers that lie in inner walls of the ventricles. The reoxygenated blood then comes back from the lungs through the pulmonary veins and fills the left atrium. The left atrium then contracts opening the mitral valve and allowing blood to fill up the left…

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