The complexity of the human body is never more evident than within the circulatory system. The circulatory system has many structures, performs vital functions, and also has diseases and disorders that are specific to it. The circulatory system works with other systems to deliver oxygen and nutrients to organs and tissues throughout the body. This functions as the transportation system of the body. The system partners with the digestive, respiratory, and urinary systems to ensure that the body functions properly and maintains homeostasis. There are two types of circulation, systemic and cardiopulmonary, that the system is responsible for. While systemic circulation ensures that blood and the nutrients it carries reaches the entire body, cardiopulmonary circulation allows blood to travel to the lungs to gain oxygen. Circulation is driven by the heart, which acts as a double pump. This is possible due to the heart’s electrical activity. WebMD explains that an electrical message travels through two types of cells in the heart: conducting cells that transport the message, and muscle cells that cause contractions of the heart muscle. The electrical system begins work with the sinoatrial node that causes the atria to contract. The signal is then sent to the ventricles by the atrioventricular bundle. Following this, the Bundle of His carries the signal through the septum, and then the Purkinje fibers cause the ventricles to contract. The circulatory system is made of blood vessels, of which are three different types- arteries, veins, and capillaries. The vessels have characteristics that distinguish them from each other. Arteries carry blood from the heart under high pressure. Because arterial blood is oxygen-rich, it is bright red. Blood leaving the heart travels through the aorta before going to arteries and then arterioles throughout the rest of the body. Veins are the opposite of arteries; they carry oxygen-poor blood to the heart, causing the blood to be a darker shade of red. Because the blood is going back to the heart, the heartbeat is not responsible for the movement of venous blood as it is with arterial blood. Instead, musculoskeletal action moves it along. Capillaries are the smallest vessels that allow blood to pass from the vessels into cells and tissues, and they are also responsible for passing waste and deoxygenated blood back into the circulatory system. To demonstrate the complexity of the network of vessels within the human body, the Cleveland Clinic states that it exceeds 60,000 miles. The heart is a very complicated structure in the system. In addition to its four chambers and four valves, the heart has several vessels. Both the superior and inferior vena cava bring deoxygenated blood into the heart. The pulmonary artery and pulmonary vein assists in cardiopulmonary circulation by taking blood to the lungs for oxygenation and bringing that newly oxygenated blood back to the heart, respectfully. The aorta is the vessel by which blood leaves the heart and travels to the rest of the body. An aneurysm is when an artery becomes inflated, which causes it to weaken. Though certain types of aneurysms can be detected routinely, others require further testing. Ultrasounds, electrocardiograms, CT scans, or an MRI may be used to diagnose an aneurysm or acquire further details such as size. Also, according to the National Heart, Lung, and Blood Institute, angiography can be used to show the inside of the affected arteries, and levels of damage and blockage can be determined. Aneurysms can be treated with medicine that relaxes vessels in an effort to prevent further damage, but, in many cases, surgery is necessary. An open abdominal procedure removes the aneurysm, and an endovascular procedure adds strength to the vessel without major surgery. Heart failure occurs when the ventricles are not working properly. Coughing, shortness of breath, and edema are common symptoms. The American Heart Association (AHA) states that a doctor will make a decision about further tests to pinpoint the issue with the ventricles once the symptoms have been discussed. These tests may include an EKG to show enlargement, a stress test to measure the amount of exertion the heart can handle, and blood testing for albumin and electrolytes that signal straining of certain organs. The AHA also states that heart failure can only be treated, not cured, based upon the patient’s desire to take action. This may include any combination of medications, procedures, rehabilitation, or lifestyle changes. Peripheral vascular disease affects the lower extremities of the body. Pain while walking and even while at rest in the legs and feet are characteristics of this disorder. A routine exam can determine that the pulse in the feet is low or nonexistent. A blood test can check cholesterol levels. The Mayo Clinic describes an ankle-brachial index test in which the blood pressure at the brachial and pedal pulse sites are compared. Although medications are often used to manage cholesterol, lifestyle changes such as an improved diet and exercise routine may be necessary to make the medication effective. These changes will improve circulation; however, amputation is sometimes needed.