Heart ‒ Section

The septum (from Latin, meaning "something that encloses") refers to a wall or partition that divides the heart into chambers. The septa are physical extensions of the myocardium lined with endocardium. The interatrial septum separates the two atria, while the interventricular septum lies between the two ventricles. This septum is considerably thicker than the interatrial septum because the ventricles generate much greater pressure during contraction. The atrioventricular septum separates the atria from the ventricles and features four openings that allow blood to flow from the atria to the ventricles and from the ventricles into the pulmonary trunk and aorta. Each of these openings between the atria and ventricles contains a valve, which ensures one-way blood flow. The valves located at the openings to the pulmonary trunk and aorta are collectively referred to as semilunar valves. *LICENSES AND ATTRIBUTIONS CC licensed content, Shared previously, Heart Anatomy, Authored by: OpenStax College. License: CC BY: Attribution. License Terms: Download for free at:http://cnx.org/contents/Y5T_wVSC@3/Heart-Anatomy* ## Keywords heart vein artery aorta pericardium cardiac muscle myocardium pulse circulation circulatory system capillaries blood