The cardiovascular system

THE CARDIOVASCULAR SYSTEM
Introduction:
The heart is a vital organ and is just a pump. The heart is a hollow, cone-shaped muscle located between the lungs and behind the sternum. Two/thirds of the heart are in the left side of the body.
The heart have two sounds , the first one is caused by the acceleration and deceleration of blood and the closure ofthe tricuspid and mitral valves . The second heart sound is caused by the same acceleration and deceleration , and the closure of the pulmonic and aortic valves.
The apex(pointedend) points down and to the left. The heart is the like the size of your fist. The heart has three layers: the smooth(internal) called endocardium. The middle layer calledmyocardium(muscle layer) and the most external called pericardium(fluid filled sac).
Chambers and Valves:
The heart is divided into four chambers : right atrium, right ventricle , leftatrium, left ventricle.
Each chamber has a sort of one-way valve , when each chamber contracts, the valve at its exit opens.
Right atrium : tricuspid valve
Right ventricle: pulmonaryvalve
Left atrium: mitral valve
Left ventricle : aortic valve
When the heart muscle contracts, process called systole, it pumps blood to the body . The first contraction is inboth atriums, pumping blood to the ventricles , and the second contraction is in both ventricles pumping blood out of the heart. The diastole is when our heart relaxes, and itpermits blood fill up the heart again.
The right side of the heart collects oxygen-poor blood from the body and pumps it to the lungs where it picks up oxygen and releases carbondioxide. The left side of the heart collects oxygen rich blood from the lungs and pumps it to the body so that the cells of the body have the oxygen they need to function properly.