The Human Body: The Cardiovascular System

Everyday our bodies need oxygen and different nutrients to function properly but in order to maintain that constancy, our blood has to be constantly moving. And in order for our cells to get transported and get everything they need, the heart needs to be beating. The cardiovascular system makes sure the levels of substances in the blood is constant by transporting these substances as circumstances change. The heart is located in the lower part of the mediastinum between the lungs. Most people think the heart lies on the left side of the body but if the chest was cut in half, two thirds of the heart would be on the left and one third would actually be on the right side of the body. The heart is triangular and roughly the size and shape …show more content…
The two upper chambers are called the atria and the two lower chambers are ventricles. The atria are smaller and have thinner, less muscular walls than the ventricles and are the receiving chambers. Blood enters through veins that open into the atria and leaves from arteries which come from the ventricles. Each chamber is named based on it’s location so there are right and left atria and right and left ventricles. The walls of the chambers are made up of cardiac muscle tissue or myocardium. Septums separate the chambers. The interatrial septum separates the atria and the interventricular septum separate the two ventricles. Smooth endocardium lines each chamber. Endocarditis, which is inflammation of the endocardium causes it to become rough which may cause clotting. The actual heart is covered with pericardium which are two layers of fibrous tissue. The inner layer is called the visceral pericardium or epicardium. The outer layer fits loosely around the heart and is called the parietal pericardium (“The Heart and Heart …show more content…
Two sides of the heart pump blood through two different circulations. Pulmonary circulation involves movement of blood from the right ventricles to the lungs. Systemic circulation involves movement from the left ventricle, throughout the body. When the heart beats the atria contract first in atrial systole. When the ventricles fill with blood, they too contract together in ventricular systole. The atria and ventricles contract as units but the right and left sides act as two separate pumps. First, deoxygenated blood enters the right atrium through two large veins called the superior vena cava and the inferior vena cava. The blood is then pumped through the right AV and enters the right ventricle, the ventricle contracts and pumps blood into the pulmonary artery. In the lungs the blood gets oxygenated and returns to the left atrium through the pulmonary veins. It passes through the left AV into the left ventricle and when the left ventricle contracts blood is forced through the aortic SL, into the aorta and distributed to the body (“The Heart and Heart