Journey of Blood Through the Heart

"The best and most beautiful things in the world cannot be seen or even touched - they must be felt with the heart"   - Hellen Keller 

          We often treat the heart as an emotional object inside us, but there's way more to the heart than that! It is one of the primary organs in the body that keeps us alive. The heart is a muscular organ that pumps blood to the other organs of the body every nanosecond of your life. This allows every cell, tissue and organ to get a fresh supply of blood and oxygen. It enhances their respective functions, keeping you alive.  

          The heart pumps oxygenated blood in the body. The organs of the body use the oxygen from the blood. There are two ways in which blood circulates throughout the body - pulmonary circulation and systematic circulation. Pulmonary circulation refers to blood going from the heart to the lungs to get oxygenated before being sent to the rest of the body. Systematic circulation refers to fresh, oxygenated blood being sent to the rest of the body. The passage of blood from the heart to the body and vice versa is a repetitive cycle. Arteries carry oxygenated blood from the heart to the various organs, cells and tissues. Veins carry deoxygenated blood back to the heart.

Figure 1: Pulmonary and Systemic Circulation

        
          The aorta is the largest artery in the body. It is responsible for sending an oxygenated supply of blood to the body. It has three branches. These branches are the brachiocephalic artery, the left common carotid artery, and the left subclavian artery. They provide blood to the head, neck and arms. The aorta is also the toughest and most elastic artery. It has to bear the high pressure of oxygenated blood that is being supplied to the organs of the body.

          The heart has four chambers, which work together to regulate the flow of blood through the heart. These are the right atrium, the right ventricle, the left atrium and the left ventricle. This is also the order in which blood flows through the heart.

          Oxygen poor blood from organs above the thoracic cavity enters the heart through the superior vena cava. Deoxygenated blood from organs below the diaphragm enters the heart through the inferior vena cava. Then, this blood flows into the right atrium. Next it flows into the right ventricle through the tricuspid valve. Valves make sure that blood doesn't flow backwards. In this case, the tricuspid valve makes sure that blood goes directly into the right ventricle and doesn't flow back into the right atrium. From the right ventricle the blood flows into the pulmonary artery through the pulmonary valve. The pulmonary artery takes the blood to the lungs so that it can get oxygenated with every inhalation. After the blood is oxygenated, the pulmonary veins take the blood back to the heart into the left atrium. Next, the bicuspid (also called mitral) valve opens to allow blood to flow from the left atrium to the left ventricle. It closes after all of the blood has accumulated in the left ventricle. The left ventricle pumps the blood into the aorta through the aortic valve, which prevents blood from flowing back into the left ventricle. Now, the blood is in the aorta, and is finally ready to be sent to the rest of the body! After the cells and tissues have utilized this oxygen rich blood, it is deoxygenated again and sent back to the heart, and this cycle repeats!  

Figure 2: Direction of Blood Flow in the Heart

          The pulmonary artery takes deoxygenated blood to the lungs. But before the deoxygenated blood reaches the pulmonary artery, it is in the right ventricle. (The right ventricle pumps deoxygenated blood into the pulmonary artery.) Therefore, the right side of the heart is responsible for pulmonary circulation. On the other hand, the left side of the heart is responsible for systematic circulation since the left ventricle pumps oxygenated blood into the aorta, and then the aorta sends this blood to the body. Out of all the chambers, the left ventricle is the toughest because it has to pump oxygen rich blood to the aorta, which will send blood to the bodily organs. 

          Arteries carry oxygenated blood away from the heart to various cells and tissues, and veins carry deoxygenated blood to the heart. However, there's an exception to this rule. Pulmonary arteries carry deoxygenated blood from the heart to the lungs, and pulmonary veins carry oxygenated blood from the lungs to the heart. Another exception lies within the umbilical blood vessels. The umbilical vein carries oxygenated blood from the mother's placenta to the fetus, and the umbilical artery carries deoxygenated blood from the fetus to the placenta.

          The heart is part of the cardiovascular system, and it plays a crucial role in the supply of blood throughout the body. Any diseases of the heart can result in a chain reaction of events that can put one's life in danger. 

Image References: 

https://anatomyandphysiologyi.com.

“New Health Advisor.” New Health Advisor, https://www.newhealthadvisor.org.