Organ System

A. Circulatory System

• made up of the heart, the blood, and the vascular system.

The HEART is made up of cardiac muscles that are involuntary and contains a large number of nuclei in order to compensate for the large amount of energy, in the form of ATP, to pump blood throughout the body.

The heart is composed of two ATRIA and two VENTRICLES; the right ventricle forms the most anterior surface of the heart while the left ventricle forms the heart apex. The ventricles are separated by the INTERVENTRICULAR SEPTUM. The muscles of the ventricles are thicker than that of the atria because these chambers are responsible for the pumping of blood to the anterior and posterior portion of the body. On the other hand, wherein the LEFT VENTRICLE is thicker than the RIGHT VENTRICLE because it is responsible for pumping blood to the rest of the body.

In between the atria and ventricles there are structures known as valves which prevent the backflow of blood to the previous chambers. The valve found at the right portion of the heart is known as the TRICUSPIC valve while the one found at the left portion of it is BICUSPID (MITRAL) valve.

The rhythmic contraction of the heart is regulated by the SINO-ATRIAL NODE (SA NODE) also known as the PACEMAKER.