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The 4 chambers of the heart


The heart consist of 4 chambers-2 atria and 2 ventricle. The atria is about 1/3 the size of the ventricle.  The left ventricle is the largest chamber of the heart.  The left ventricle has about three time the mucsle than the right ventricle.

The chambers of the heart provide a multiple step pathway for blood to be first sent to the lungs for respiration and then dispensed to the body's cells to keep us alive.  Read to learn about the 4 chambers of the heart.  Valves help the chambers of the heart to help move the blood along in one direction.  There are two main valves:  the Mitral valve and the Tricuspid valve. 




    The Right Atrium

The right atria receives the oxygen from the inferior and the superior vena cava and blood from the coronary sinus(the outlet from the coronary circulation.)   The right atrium also effects heart rate through barroreceptors present on its inside surface.  The right atrium also effects heart rate through barroreceptors present on its inside surface.  The right and left atria also perform an endocrine function with the release of atrial natriuretic peptide (ANP), blunting the effects of epinephrine, endothelin and the renin-angiotension-aldosterone cascade.  When the artia is stretched, ANP  is released.  When this happens the effects are decreased heart rate; reduced preload through vasodilation and increased urinary output;stimulation of the Vagus nerve; and inhibited ventricular hypertrophy.

The Right Ventricle
The right ventricle is separated from the left ventricle by the septum. The right ventricle ejects blood through the pulmonic valve into the pulmonary arteries.  The right ventricle's wall thickness for an adult is 4-5 mm. It's right ventricle's myocardial blood supply is primarily from the right coronary artery.   The lower right ventricle of the heart receives deoxygenated blood from the right atrium  and pumps it under low pressure into the lungs.  It receives blood from the right atrium and pumps it to the main pulmonary artery.  The main pulmonary artery extends from the right ventricle and branches into left and right pulmonary arteries, which extend to the lungs. Here oxygen-poor blood picks up oxygen and is returned to the heart via the pulmonary veins.


The Left Atrium
Like the right atrium, the left atrium fulfills several functions.  The functions are... 1. atrial kick for the left of the heart/ 2. influences the rate of the heart/ 3. and has endocrine qualitites.  The left atrium is slightly larger than the right atrium.  The left atrium recieves oxygen-rich blood which pumps the blood into the left ventricle.