<P> A ventricle is one of two large chambers in the heart that collect and expel blood received from an atrium towards the peripheral beds within the body and lungs . The atrium (an adjacent / upper heart chamber that is smaller than a ventricle) primes the pump . Interventricular means between the ventricles (for example the interventricular septum), while intraventricular means within one ventricle (for example an intraventricular block). </P> <P> In a four - chambered heart, such as that in humans, there are two ventricles that operate in a double circulatory system: the right ventricle pumps blood into the pulmonary circulation to the lungs, and the left ventricle pumps blood into the systemic circulation through the aorta . </P> <P> Ventricles have thicker walls than atria and generate higher blood pressures . The physiological load on the ventricles requiring pumping of blood throughout the body and lungs is much greater than the pressure generated by the atria to fill the ventricles . Further, the left ventricle has thicker walls than the right because it needs to pump blood to most of the body while the right ventricle fills only the lungs . </P> <P> On the inner walls of the ventricles are irregular muscular columns called trabeculae carneae which cover all of the inner ventricular surfaces except that of the conus arteriosus, in the right ventricle . There are three types of these muscles . The third type, the papillary muscles give origin at their apices to the chordae tendinae which attach to the cusps of the tricuspid valve and to the mitral valve . </P>

Why does the ventricles have thick walls than atria
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