Circulatory System Essay

1290 Words 6 Pages
The circulatory system is something most living creatures have. The purpose of the circulatory system to help provide oxygen molecules to your whole body. It also helps circulate carbon dioxide, nutrients, and hormones throughout the body. (Johnson, p 651) Blood is a liquid that flows through the body. It is composed of several different particles: Red blood cells, white blood cells, plasma, and platelets. Red blood cells are cells in the blood that transports oxygen molecules and nutrients to the whole body. Red blood cells are created inside the bone by the bone marrow. (What are red blood cells?) White blood cells are cells in the body that fight off infections in the body. They circulate along the other substances of blood to make sure …show more content…
Blood vessels vary sizes all depending on how much blood flows through. Most blood vessels are composed of 3 different layers: tunica externa, tunica media, and tunica intima. The tunica externa are composed of connective tissues and elastic fibers. They stretches the blood vessels out for higher amount of blood to flow. The tunica media is also composed of elastic fibers, but have a smooth muscle layer instead of connective tissue. The tunica media helps regulate blood pressure and the flow of blood in the blood vessels. The thinnest layer of the blood vessel structure is the tunica intima. Blood flows through the thin layer of endothelial cells. (“Arteries, Veins, and Capillaries”) Blood goes through the body in blood vessels called arteries, capillaries and veins. Arteries keep blood flowing away from the heart and throughout the body. The blood that travels through the arteries carries o2 molecules to give to the whole body. Arteries are thicker than any blood vessel in the body because it helps with the high pressures of blood being pumped from the heart. Once the blood traveling through the arteries reach the end of that particular blood vessel, it goes through a smaller blood vessel called the capillaries. In the capillaries, blood exchanges o2 molecules and nutrients for carbon dioxide and waste with tissue cell. Afterwards, the blood would carry the carbon dioxide and waste and go through the …show more content…
The heart has 4 sections inside: left and right atria and left and right ventricle. The right atrium receives blood that is low on oxygen molecules from the superior and inferior vena cavae. The superior vena cava is one of the largest veins in the body that brings de-oxygenated blood from the lower part of the body to the right atrium. The inferior vena cava is the other largest vein in the body that brings blood into the right atrium from the top of the upper parts of your body. The right atrium pumps blood through the tricuspid valve and into the right ventricle. The tricuspid valve would open up once blood is ready to go to the right ventricle. Once blood has reached the right ventricle, the valve would close. The right ventricle’s job is to pump blood into the pulmonary valve and into the pulmonary artery. The pulmonary valve would open up once blood is ready to travel out of the heart through the pulmonary artery. Afterwards, the pulmonary artery would pump blood through the lungs to collect oxygen and back into the heart through the pulmonary vein. The vein would help blood flow back into the heart, entering the left atrium. The left atrium would pump blood through the mitral valve and into the left ventricle. The left ventricle pumps the oxygenated blood through the aortic valve and out of the heart through the aorta. The aorta helps blood go through the blood vessels to give off oxygen to the

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