The Circulatory System
The circulatory system, also known as the cardiovascular system, is the combined function of the heart, blood, and blood vessels to carry oxygen as well as nutrients to organs and tissues all throughout the body and carry away waste products. When the body is under stress such as exercise, the circulatory system can increase blood flow to various organs and muscles to meet increased energy demands, and help to regulate body temperature. It also is involved with the immune system in fighting against an unknown or foreign substance that invades the body, by swiftly sending the disease fighting elements such as white blood cells and antibodies to the area under attack. Additionally, in the case of injury or bleeding, the circulatory system sends clotting cells and proteins to the affected area to stop blood loss.
The circulatory system has three structural elements; the heart, blood and blood vessels. The circulatory system’s engine is the heart, which is divided into four chambers: the right atrium, the right ventricle, the left atrium, and left ventricle. The walls of the heart are composed of muscle called myocardium. This muscle contracts and relaxes continuously to pump blood. Blood consists of three types of cells: oxygen carrying red-blood cells, disease-fighting white blood cells, and blood-clotting platelets. All of these cells are carried through the blood vessels in a yellowish liquid called plasma that contains of water, salts, proteins, vitamins, minerals, hormones, dissolved gases, and fats. There are three types of blood vessels that form a complex network of tubes throughout the body. Arteries carry blood away from the heart, veins carry blood toward the heart, and capillaries are tiny links between the veins and arteries, and are the place where oxygen and nutrients are diffused into the tissues.
There are many diseases and disorders associated with the circulatory system, however, the most common are Coronary Artery Disease and Stroke. Coronary artery disease involves an obstruction in the arteries that supply oxygen and nutrients to the heart, and includes angina pectoris and myocardial infarction. Strokes are caused when a clot blocks blood flow to the brain.
Many people with coronary artery disease do not experience symptoms. When the obstruction is bad enough, however it may cause angina pectoris which is characterized by chest pain that feels like something is squeezing or compressing the chest during exertion. It happens when the heart’s oxygen demands cannot be met because of the blocked coronary artery. Rest relieves the pain, or sometimes it becomes necessary to take a medication called nitroglycerine. Nitroglycerine acts by dilating the coronary vessels, and allowing more blood to flow through. A myocardial infarction is also called a heart attack. This occurs when a coronary artery is completely occluded. When deprived of oxygen, that portion of the myocardium will die. When a large portion of the myocardium dies, the heart will fail as a pump, and the person will die. The first few hours after a heart attack are the most important because abnormal heart rhythms may occur. Symptoms of a heart attack are: Uncomfortable pressure, fullness, squeezing or pain in the center of the chest that lasts more than a few minutes, or goes away and comes back, pain that spreads to the shoulders, neck or arms, chest discomfort with lightheadedness, fainting, sweating, nausea or shortness of breath. Heart attack patients are usually treated in a special hospital unit for a few days to enable electronic monitoring of the heart rhythm.
Treatment sometimes involves only monitoring, but if the blockage is extensive, open-heart surgery is required to replace the affected artery. Recent research is toward prevention, with findings that indicate a diet low in fat and regular exercise will help prevent coronary artery disease. One recent study has also found that over a 14-year period has an increased intake of two vitamins, folate and vitamin B-6, is predictive of reduced risk of coronary heart disease.
Strokes are caused by blockage of an artery that is supplying the brain. When oxygen rich blood cannot reach brain cells, they die. This can affect whatever body functions that part of the brain controls. Signs of a stroke include: Sudden numbness or weakness of face, arm or leg, especially on one side of the body, sudden confusion, trouble speaking or understanding, sudden trouble seeing in one or both eyes, sudden trouble walking, dizziness, loss of balance or coordination, and sudden, severe headache with no known cause. Treatment includes prevention, such as when a neck artery has become partially blocked, surgery might be used to remove the buildup of plaque. This is called carotid endarterectomy. Recent research has led to a new technique called cerebral angioplasty. The newest treatment for strokes is with a drug called TPA. This drug dissolves clots and can be used to treat strokes in some cases. I was unable to document a source for how the use of TPA was first discovered for stroke treatment.