The Circulatory

The Circulatory System Chapter 23 Heart Facts • Cardio = Heart • Vascular = Vessels • The heart is located between the lungs ( two-thirds of it lies left of the chest midline) • The Heart is made up of a powerful muscle called Myocardium. • Anxiety, fear, stress and strenuous activity cause your heart to beat faster. • The heart is about the size of a man's fist. • The heart, completely separates oxygenated from deoxygenated blood. • The heart beats or contracts around 70 times per minute. • The human heart will undergo over 3 billion contraction/cardiac cycles during a normal lifetime. Cardiovascular System • The main roles of the cardiovascular system in the body is to: – transport oxygen and nutrients to all tissues in the body to maintain bodily life processes – remove waste products from all tissues in the body. • The oxygen and nutrients the cells use to carry out their functions produce waste that must be removed. Cardiovascular System – the blood vessels (the pipes through which the blood flows) – the heart (the pump which forces blood to flow through the blood vessels.) • The Cardiovascular system consists of: – the blood (carries oxygen, nutrients and waste (CO2) products throughout the body) • The heart's only function is to pump blood. • The right side of the heart pumps blood to the lungs, where oxygen is added to the blood and carbon dioxide is removed from it. • The left side pumps blood to the rest of the body, where oxygen and nutrients are delivered to tissues and waste products (such as carbon dioxide) are transferred to the blood for removal by other organs (such as the lungs and kidneys). Structure of the Heart • The human heart is a hollow, upside-down, pear-shaped shell. • The inside of the heart is divided into four chambers, the left and right atria and the left and right ventricles, which periodically fill with blood and empty. • The two atria form the curved top of the heart and receive blood from the veins. • The ventricles meet at the bottom of the heart to form a pointed base which points toward the left side of the chest. • They give oxygen rich blood to the arteries to take to the body cells. • The left ventricle contracts most forcefully, so the heart beat is felt most strongly on the left side of the chest. • A wall, called the septum, separates the right and left sides of the heart. • A valve connects each atrium to the ventricle below it. • The mitral or bicuspid valve connects the left atrium with the left ventricle. • The tricuspid valve connects the right atrium with the right ventricle. Septum: • The Septum is a wall that separates the right and left sides of the Heart. Superior Vena Cava: • The importance of the Superior Vena Cava is to return blood back to the Right Atrium from the upper part of the body. It is one of the largest veins in the body. Inferior Vena Cava: • The Inferior Vena Cava is important for carrying the blood back to the Right Atrium from the lower part of the body. Pulmonary Arteries: • The Pulmonary Arteries carry the blood from the Right Ventricle to both of the lungs. There the blood is oxygenated and sent to the Left Atrium in the heart Pulmonary Veins: • The Pulmonary Veins carry the oxygenated blood back to the Left Atrium in the heart The Aorta Aorta: • • • • The Aorta is the largest blood vessel in the body. The inner diameter of the Aorta is about 1 inch. The Aorta carries oxygenated blood to every other part of the body. The Aorta receives it's blood from the Left Ventricle • Left Ventricle:The chamber of the Left Ventricle has walls that are three times the thickness of the Right Ventricle. • This is important because the oxygenated blood that it receives from the Left Atrium has to be pump throughout the body. • The Bicuspid Valve (Mitral Valve) closes and the blood is collected in the Left Ventricle. • Left Atrium:The Left Atrium receives blood from four Pulmonary Veins. • The blood received from the lungs has been oxygenated. • The oxygenated blood that is collected in Left Atrium is then pumped into the Left Ventricle through the Bicuspid Valve. • Right Atrium:The Right Atrium is larger than the Left Atrium but has thinner walls. • The Right Atrium has two major veins that returns blood to the heart from all parts of the body. • Two major veins returning the blood to the heart are the Superior Vena Cava and the Inferior Vena Cava. • These two veins are sometimes called the "Great Veins". • The Superior Vena Cava returns the deoxygenated blood from the upper part of the body and the Inferior Vena Cava returns the deoxygenated blood from the lower part of the body. • After the blood is collected in the Right Atrium it is pumped into the Right Ventricle through the Tricuspid Valve Circulatory Circuits There are three Circulatory ”Circuits": Pulmonary Circulation:  Involves the "right heart," delivers blood to and from the lungs.  The pulmonary artery carries oxygen-poor blood from the "right heart" to the lungs, where oxygenation and carbon-dioxide removal occur.  Pulmonary veins carry oxygen-rich blood from the lungs back to the "left heart.” Systemic Circulation: • Driven by the "left heart," carries blood to all of your organs and body tissues through the aorta (except for the heart and lungs) • Most extensive circuit • Once nutrients and oxygen are delivered by blood to your cells and exchanged for carbon dioxide and wastes, the blood returns to the heart in veins • From the head and neck areas, blood returns through the superior vena cava • From your abdomen and lower parts of the body, blood returns through the inferior vena cava • Coronary Circulation: • The flow of blood to the tissues of the heart. – If coronary circulation is blocked, oxygen cannot reach the cells of the heart and the result is a heart attack Flow of Blood • Blood travels the following circuit: • Blood from the body, which is depleted of oxygen and laden with carbon dioxide, flows through the two largest veins (the venae cavae) into the right atrium. • When the right ventricle relaxes, blood in the right atrium pours through the tricuspid valve into the right ventricle. • When the right ventricle is nearly full, the right atrium contracts, propelling additional blood into the right ventricle, which then contracts. • This contraction propels blood through the pulmonary valve into the pulmonary arteries, which supply the lungs. • In the lungs, blood flows through the tiny capillaries that surround the air sacs. • Here, the blood absorbs oxygen and gives up carbon dioxide, which is then exhaled. • Blood from the lungs, which is now oxygen-rich, flows through the pulmonary veins into the left atrium. • When the left ventricle relaxes, the blood in the left atrium pours through the mitral valve into the left ventricle. • When the left ventricle is nearly full, the left atrium contracts, propelling additional blood into the left ventricle, which then contracts. • The contraction of the left ventricle propels blood through the aortic valve into the aorta, the largest artery in the body. • This blood carries oxygen to all of the body except to the lungs. • Once nutrients and oxygen are delivered by blood to your body cells and exchanged for carbon dioxide and wastes, the blood returns to the heart in veins. • The oxygen poor blood enters the right atrium via the the superior and inferior vena cava and starts the process all over again. • Flow of Blood through the Heart Blood Vessels • The three blood vessels are: – Arteries – Veins – Capillaries • In the middle 1600s scientists confirmed that blood circulates only in one direction and is moved by the pumping action of the heart. • Scientists had no idea how the blood moved from the arteries to the veins. • With the invention of the microscope, capillaries were seen. Arteries Arteries: • Move blood away from the heart to the body cells • Rich in oxygen with the exception of the pulmonary artery, which carries blood to the lungs to be oxygenated. • Carry blood away from the heart at relatively high pumping pressure • Arteries divide into progressively thinner tubes and eventually become fine branches called arterioles • Arteries and arterioles have muscular walls that can adjust their diameter to increase or decrease blood flow to a particular part of the body. Veins • Blood leaving the capillaries flows into a series of progressively larger vessels, called venules, which in turn unite to form veins. • Veins are responsible for returning blood to the heart after the blood and the body cells exchange gases, nutrients, and wastes. • Pressure in veins is low, so veins depend on nearby muscular contractions to move blood along. • Veins have much thinner walls than do arteries, largely because the pressure in veins is so much lower. • Veins can widen (dilate) as the amount of fluid in them increases. • Veins have one way valves to keep blood flowing in the same direction. • When these valves leak, the backflow of blood can cause the veins to stretch and become elongated and convoluted. • Stretched, convoluted veins near the body's surface are called varicose veins. Capillaries • Capillaries are tiny, extremely thin-walled vessels that act as a bridge(they connect) between arteries (which carry blood away from the heart) and veins (which carry blood back to the heart). • The thin walls of the capillaries allow oxygen and nutrients to pass from the blood into tissues and allow waste products to pass from tissues into the blood. (diffusion) • The arterioles branch into the microscopic capillaries • Capillaries are one cell thick • The extensive network of capillaries is estimated at between 50,000 and 60,000 miles long. Blood Pressure and Heart Rate • Normal blood pressure is important for proper blood flow to the body's organs and tissues. • Each heartbeat forces blood to the rest of the body. • Blood pressure depends on many factors, including: – the amount of blood pumped by the heart. – The diameter of the arteries through which blood is pumped • The force of the blood on the walls of the arteries is called blood pressure. • Generally, blood pressure is higher when more blood is pumped by the heart, and the diameter of an artery is narrow. • Stressful situations can result in a temporary increase in blood pressure. • If left untreated, high blood pressure can damage important organs, such as the brain and kidneys as well as lead to a stroke. Blood Pressure and Heart Rate • One heartbeat, or cardiac cycle, includes atrial contraction and relaxation, ventricular contraction and relaxation, and a short pause. • Atria contract while ventricles relax • Heart valves open and close to limit flow to a single direction. • The cardiac cycle consists of two parts: – systole (contraction of the heart muscle in the ventricles) – diastole (relaxation of the ventricular heart muscles). • Blood pressure is measured both as the heart contracts, which is called systole, and as it relaxes, which is called diastole. • When the ventricles contract, they force the blood from their chambers into the arteries leaving the heart. • The increased pressure on the arteries due to the contraction of the ventricles (heart pumping) is called systolic pressure • When the ventricles relax, blood flows in from the atria. The decreased pressure due to the relaxation of the ventricles (heart resting) is called diastolic pressure. • Blood pressure is measured in mm of mercury, with the systole in ratio to the diastole. Healthy young adults should have a ventricular systole of 120mm, and 80mm at ventricular diastole, or 120/80 High Blood Pressure It's important to realize that very often HIGH BLOOD PRESSURE has NO symptoms. So you may feel fine until you are hit with a stroke or heart attack. But here's the common symptoms of a dangerous blood pressure: • • • • • • • Persistent throbbing Blurred vision Nausea and vomiting Ringing in your ears Right side chest pain Swollen feet Mini-stroke Headaches Lowering High Blood Pressure • Significant lowering of blood pressure in mild HIGH BLOOD PRESSURE can be achieved just by simple: • regular exercise • eating a low grease and salt diet • quitting smoking. Heart Disease Atherosclerosis • cholesterol in your blood may be stored in your arteries (blood vessels) and cause them to narrow. • Large deposits of cholesterol can completely block an artery, so the blood can't flow through. • If an artery that supplies blood to your heart becomes blocked, a heart attack can occur. • If an artery that supplies blood to your brain becomes blocked, a stroke can occur. Heart Disease Hypertension • Hypertension means high blood pressure. • High blood pressure is an increased pressure in your blood vessels, and therefore there is less space for your blood to travel through. • If you have mild, moderate, or severe hypertension, you have an increased risk of having a heart attack or a stroke. Risk factors for heart disease • • • • • • • • Having already had a heart attack Being a man 45 years of age or older Being very overweight Being a woman who is going through menopause or has completed menopause Smoking cigarettes Having high blood pressure or diabetes Having a father or brother who had heart disease before he was 55 (mother or sister who had heart disease before she was 65) Being inactive Facts about Blood • • • • • • • • • The blood volume in the body varies according to size of individual. Blood accounts for about 8 percent of the body weight. The average adult has between 5 to 6 liters of blood or blood volume. Blood carries oxygen and nutrients to all of the body. Blood fights against infection and helps heal wounds. There are four main blood types: A, B, AB and O. There are about one billion red Blood cells in a few drops of whole Blood. Red Blood cells live about 120 days in our bodies. Type AB plasma has been considered as the universal blood plasma type, and therefore AB can receive any blood type. Functions of the Blood • The blood has four main jobs: – Carries oxygen from your lungs to all body cells and removes carbon dioxide from you body cells and carries it to the lungs to be exhaled – Carries waste products of cell activity to the kidneys to be removed. – It transports nutrients from the digestive system to the body cells – Materials in the blood fight infections and help heal wounds. • Platelets are responsible for coagulation of blood at the point of an injury to a blood vessel. • Without platelets, our blood would not be able to clot and hemorrhaging or uncontrolled bleeding would result. • Most of the blood is made up of a watery, protein-laden fluid called plasma. • A little less than half of this blood volume is composed of red and white blood cells • The other solid elements are called platelets. Red Blood Cells • • • • Red blood cells are the oxygen carriers. A cubic millimeter of blood has more than 5 million red blood cells. Made in the marrow of the bone at a rate of 2-3 million per second The same number wear out and are destroyed in the same time period • Contains hemoglobin, a chemical that can carry oxygen and carbon dioxide • As they travel away from the heart, they travel through smaller and smaller arteries, finally arriving at the collections of microscopic blood vessels known as capillaries. • Here, they exchange nutrients and oxygen for cellular waste products. • The waste products are eventually eliminated from the blood stream through the urinary and respiratory systems. • The exchange of oxygen and nutrients between the red blood cells and the surrounding tissues occurs through a process called diffusion. White Blood Cells • • • • • White blood cells defend the body against bacteria and other enemies. White blood cells come in many varieties. Each fights the body’s enemies in a different way. Some white blood cells produce antibodies White blood cells are formed in the red bone marrow, lymphatic tissue, spleen, lymph nodes, and thymus. • They travel throughout the circulatory system to sites that they are needed. • They actually slip between the cells of capillary walls to get to infected areas of your body. • White blood cells are colorless. • The white blood cells are less numerous than the red blood cells and larger than red blood cells. • Compared to the red blood cells the white blood cells number only 1 white blood cell to 700 red blood cell. (5,000 - 10,000 per cubic millimeter) • The life span of white blood cells varies depending on the service they have to perform. Plasma • Plasma makes up a little more than 50 percent of the blood. • The composition of blood is 90 percent water and 10 percent dissolved substance. • The color of Plasma is like the color straw. • Plasma contains thousands of different substances like proteins, glucose, salts, vitamins, hormones, and antibodies. • Plasma is what keeps the blood flowing. Platelets Platelets are small fragments of cells that clump together and stick to inner surface of blood vessels to plug up leaks. • The platelets release a substance for clotting of blood. • The platelets cause the injured site to shrink and seal off. • • • • The platelets get their name from their shape. They look like oval plates. Platelets have a life span of 5 to 9 days. The platelets are formed in the bone marrow. The number of platelets fall between the number of white blood cells and red blood cells. (400,000 per cubic millimeter) Blood Clotting • This begins the clotting process. Platelets immediately begin to adhere to the cut edges of the artery; they release chemicals to attract even more platelets. • Eventually a platelet plug is formed, and the external bleeding stops. • Hemophilia is a genetic disease that lacks one of the clotting factors that begin the clotting process • When a blood vessel becomes damaged, as shown here, the blood cells and plasma begin oozing out into the surrounding tissue. Blood Types • Everybody has a blood type. • The most common blood type classification system is the ABO system discovered by Karl Landsteiner in the early 1900s. • There are four types of blood in the ABO system: A, B, AB, and O. • Your blood type is established before you are born, by specific genes inherited from your parents. • You receive one gene from your mother and one from your father; these two combine to establish your blood type. • • • • • • These genes were labeled "A" and "B." The presence of only A molecules results in type A blood. The presence of only B molecules results in type B blood. The presence of both molecules results in type AB blood. When no molecules are present the blood is type O blood. If blood of different types are mixed they may being to clump together in the veins, sometimes causing fatal conditions. Antibodies • Type A: A antigens on the red cells and anti B antibodies in the plasma • Type B: B antigens on the red cells and anti A antibodies in the plasma • Type AB: both A and B antigens on the red cells and no blood type antibodies in the plasma • Type O: no antigens on the red cells and both anti A and anti B antibodies in the plasma Blood Transfusion Transfusion Reactions • Blood typing prevents transfusion reactions which are caused by blood group antibodies. • Someone with blood type A does not have the B group on his red cells, and always makes an antibody against B. • If he receives blood from someone with B or AB blood his anti-B will destroy the transfused red cells, a serious reaction that, in the worst case, can lead to death. • Blood donors and recipients must be typed and matched very carefully before transfusions are given. • Group AB Blood has both A and B antigens on red cells but neither anti-A antibody nor anti-B anti body in its plasma. • AB blood cannot cause the clumping of red cells of any other groups, and therefore persons with AB blood are called universal recipients. • Group O Blood has neither A nor B antigens on red cells, and both anti-A antibody and anti-B antibody in the plasma. • Group O blood cannot be clumped by any human blood, and therefore persons with Group O are called universal donors • Someone with type-AB blood can receive any type blood with no ill effects, while people with type-O blood can only take their own type. • People with type-A blood can receive A or O, and people with type-B blood can take B or O. Diseases of the Blood Anemia • running low on red blood cells. • Red blood cells are important because they carry oxygen all throughout your body. • Oxygen gives you energy. • People with anemia often feel weak and tired. • Often caused by a lack of iron in their diet Leukemia (Cancer of the blood) • When leukemia develops, the body produces large numbers of abnormal blood cells. • In most types of leukemia, the abnormal cells are white blood cells. • The leukemia cells usually look different from normal blood cells, and they do not function properly.