Cardiac Cycle
Deoxoygenated blood enters the body into the right atrium via the Vena cava. Tricuspid valve closed.
Once the blood has entered, the blood is pushed down into the right Ventricle. The Pulmonary valve opens.
The blood then pumps up through the Pulmonary Artery to the Lungs where gaseous exchange takes place and carbon dioxide diffuses out of the blood and oxygen is diffused in from the lungs.
The oxygenated blood is returned to the heart via the pulmonary Vein into the left atrium. Bicuspid Closed, cardiac muscle contracts and Bicuspid valve opens
The blood is pumped down into the left ventricle.
The blood is pumped from the left ventricle up through the Aorta and is pumped around the body providing oxygen to all the organs. Aortic valve opens.
Then this process happens again.
Your heart’s electrical system is made up of three main parts:
The Sinoartrial (SA) node, located in the right atrium.
The Artrioventicular (AV) node, located on the septum close to the tricuspid valve.
The His-Purkinje System, located along the walls of your heart’s ventricles.
Each beat is controlled by an alectrical signal from within your heart muscle. In a healthy heart, each beat begins with a signal from the SA node. His is called your heart’s natural pacemaker. Your pulse is the number of signals the SA node produces per minute.
(http://www.nhlbi.nih.gov/health/dci/Diseases/hhw/hhw_electrical.html)
The upper chambers are stimulated; this follows by a slight delay to allow the two atria to empty. Then the two ventricles are electrically stimulated.
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