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4th Years University of Babylon Anesthesia College of Nursing Lec.4 Dr. Naji Yassesr Al-Mayyahi _______________________________________________________________ I. Cardiovascular System The cardiovascular system consists of the heart, blood vessels, and the approximately 5 liters of blood that the blood vessels transport. Responsible for transporting oxygen, nutrients, hormones, and cellular waste products throughout the body, the cardiovascular system is powered by the body’s hardest-working organ — the heart, which is only about the size of a closed fist. Even at rest, the average heart easily pumps over 5 liters of blood throughout the body every minute... The Heart The heart is a muscular pumping organ located medial to the lungs along the body’s midline in the thoracic region. The bottom tip of the heart, known as its apex, is turned to the left, so that about 2/3 of the heart is located on the body’s left side with the other 1/3 on right. The top of the heart, known as the heart’s base, connects to the great blood vessels of the body: 1.the aorta, 2.vena cava, 3.pulmonary trunk, 4.and pulmonary veins. Circulatory Loops There are 2 primary circulatory loops in the human body: the pulmonary circulation loop and the systemic circulation loop. 1.Pulmonary circulation transports deoxygenated blood from the right side of the heart to the lungs, where the blood picks up oxygen and returns to the left 1 side of the heart. The pumping chambers of the heart that support the pulmonary circulation loop are the right atrium and right ventricle 2.Systemic circulation carries highly oxygenated blood from the left side of the heart to all of the tissues of the body (with the exception of the heart and lungs). Systemic circulation removes wastes from body tissues and returns deoxygenated blood to the right side of the heart. The left atrium and left ventricle of the heart are the pumping chambers for the systemic circulation loop. Blood Vessels Blood vessels are the body’s highways that allow blood to flow quickly and efficiently from the heart to every region of the body and back again. The size of blood vessels corresponds with the amount of blood that passes through the vessel. All blood vessels contain a hollow area called the lumen through which blood is able to flow. Around the lumen is the wall of the vessel, which may be thin in the case of capillaries or very thick in the case of arteries. There are three major types of blood vessels: arteries, capillaries and veins. Blood vessels are often named after either the region of the body through which they carry blood or for nearby structures. Arteries and Arterioles: Arteries are blood vessels that carry blood away from the heart. Blood carried by arteries is usually highly oxygenated, having just left the lungs on its way to the body’s tissues. The pulmonary trunk and arteries of the pulmonary circulation loop provide an exception to this rule – these arteries carry deoxygenated blood from the heart to the lungs to be oxygenated. Smaller arteries are more muscular in the structure of their walls. The smooth muscles of the arterial walls of these smaller arteries contract or expand to regulate the flow of blood through their lumen. In this way, the body controls how much blood flows to different parts of the body under varying 2 circumstances. The regulation of blood flow also affects blood pressure, as smaller arteries give blood less area to flow through and therefore increases the pressure of the blood on arterial walls. Arterioles are narrower arteries that branch off from the ends of arteries and carry blood to capillaries. They face much lower blood pressures than arteries due to their greater number, decreased blood volume, and distance from the direct pressure of the heart. Thus arteriole walls are much thinner than those of arteries. Arterioles, like arteries, are able to use smooth muscle to control their aperture and regulate blood flow and blood pressure. Capillaries: Capillaries are the smallest and thinnest of the blood vessels in the body and also the most common. They can be found running throughout almost every tissue of the body and border the edges of the body’s avascular .tissues. Capillaries connect to arterioles on one end and venules on the other Precapillary sphincters are bands of smooth muscle found at the arteriole ends of capillaries. These sphincters regulate blood flow into the capillaries. Since there is a limited supply of blood, and not all tissues have the same energy and oxygen requirements, the precapillary sphincters reduce blood flow to inactive tissues and allow free flow into active tissues. Veins and Venules: Veins are the large return vessels of the body and act as the blood return counterparts of arteries. Because the arteries, arterioles, and capillaries absorb most of the force of the heart’s contractions, veins and venules are subjected to very low blood pressures. This lack of pressure allows the walls of veins to be much thinner, less elastic, and less muscular than the walls of arteries. 3 Cardiovascular disease Heart and blood vessel disease — also called heart disease — includes numerous problems, many of which are related to a process called atherosclerosis. Atherosclerosis is a condition that develops when a substance called plaque builds up in the walls of the arteries. This buildup narrows the arteries, making it harder for blood to flow through. If a blood clot forms, it can stop the blood flow. This can cause a heart attack or stroke Coronary artery disease (CAD), also known as ischemic heart disease is a group of diseases that includes: 0(IHD stable angina, unstable angina, myocardial infarction, and sudden cardiac It is within the group of cardiovascular diseases of which it is the most .death A common symptom is chest pain or discomfort which may .common type travel into the shoulder, arm, back, neck, or jaw. Occasionally it may feel like heartburn. Usually symptoms occur with exercise or emotional stress, last less than a few minutes, and get better with rest. Shortness of breath may also occur and sometimes no symptoms are present. The first sign is occasionally a heart .attack. Other complications include heart failure or an irregular heartbeat heart attack A heart attack occurs when the blood flow to a part of the heart is blocked by a blood clot. If this clot cuts off the blood flow completely, the part of the heart muscle supplied by that artery begins to die. Most people survive their first heart attack and return to their normal lives to enjoy many more years of productive activity. But having a heart attack does mean you have to make some changes. The doctor will advise you of medications and lifestyle changes according to how badly the heart was damaged and what degree of heart disease caused the heart attack. Limitation of blood flow to the heart causes ischemia (cell starvation secondary to a lack of oxygen) of the myocardial cells. Myocardial cells may die from lack of oxygen and this is called a myocardial infarction (commonly called a heart attack). It leads to heart muscle damage, 4 heart muscle death and later myocardial scarring without heart muscle regrowth. Chronic high-grade stenosis of the coronary arteries can induce transient ischemia which leads to the induction of a ventricular arrhythmia, which may terminate into ventricular fibrillation leading to death Other Types of Cardiovascular Disease Heart failure: This doesn't mean that the heart stops beating. Heart failure, sometimes called congestive heart failure, means the heart isn't pumping blood as well as it should. The heart keeps working, but the body's need for blood and oxygen isn't being met. Heart failure can get worse if it's not treated. If your loved one has heart failure, it's very important to follow the doctor's orders. .Learn more about heart failure Arrhythmia: This is an abnormal rhythm of the heart. There are various types of arrhythmias. The heart can beat too slow, too fast or irregularly. Brady cardia is when the heart rate is less than 60 beats per minute. Tachycardia is when the heart rate is more than 100 beats per minute. An arrhythmia can affect how well the heart works. The heart may not be able to pump enough blood to meet the body's needs. Learn more about arrhythmia Heart valve problems: When heart valves don't open enough to allow the blood to flow through as it should, it's called stenosis. When the heart valves don't close properly and allow blood to leak through, it's called regurgitation. When the valve leaflets bulge or prolapse back into the upper chamber, it’s a condition called mitral valve prolapse. When this happens, they may not close properly. This allows blood to flow backward through them. Discover more about the roles your heart valves play in healthy circulation. 5 Cardiac arrest: Cardiac arrest is a sudden stop in effective blood flow due to the failure of the heart to contract effectively. Symptoms include loss of consciousness and abnormal or absent breathing. Some people may have chest pain, shortness of breath, or nausea before this occurs. If not treated within minutes, death usually occurs. The most common cause of cardiac arrest is coronary artery disease. Less common causes include major blood loss, lack of oxygen, very low potassium, heart failure, and intense physical exercise. A number of inherited disorders may also increase the risk including long QT syndrome. The initial heart rhythm is most often ventricular fibrillation. The diagnosis is confirmed by finding no pulse. While a cardiac arrest may be caused by heart attack or heart [.failure these are not the same Risk factors: Risk factors include: high blood pressure, smoking, diabetes, lack of exercise, obesity, high blood cholesterol, poor diet, and excessive alcohol, Other risks include depression . 6