1. Transportation

6. Blood Some biologists have long referred to human blood as "the sea within us." Our blood makes available to all of our body cells all of the materials necessary for life.

7. The blood is the transportation system in the human body that carries food, oxygen, and hormones to all of the body cells, regardless of how far they are situated from the heart and lungs. The blood also carries waste products and carbon dioxide away from body cells so that the body rids itself of them.

8. The average adult possesses about 5 litres of blood. It accounts for 6 to 8 percent of the person's body mass on average. Blood is actually a type of tissue in the human body.

9. In the human body, blood has complex functions that help to maintain homeostasis in the body. These include: 1. Transport – oxygen, carbon dioxide, food, waste, hormones 2. Protection – blood clotting, defence against disease 3. Regulation – hormones, heat distribution

11. The Components of Blood Human blood is composed of water, various dissolved substances, and living cells. More specifically, the blood is composed of a yellowish fluid, called plasma, in which three basic cell types are suspended. The different blood cells work together to accomplish the role of transportation within the body.

13. Plasma Liquid part of the blood. Composed of water (90%) and various dissolved substances (10%). Makes up about 55% of blood by volume. Dissolved substances in plasma include blood proteins, glucose, vitamins, minerals, dissolved gases, hormones, and waste materials.

14. The body monitors the concentrations of these substances and makes sure that they remain within healthy limits. Light yellow in colour and appears somewhat cloudy due to the substances dissolved within it.

15. Erythrocytes (Red Blood Cells) Make blood appear red. Membranous sacs filled with a protein called hemoglobin, which contains iron. About 7.0 micrometres (10 -6 metre) in diameter. Do not have the ability to reproduce because they do not possess nuclei.

16. When the body needs more erythrocytes, it produces new erythrocytes instead of depending on existing red blood cells to divide. Produced in the bone marrow. A typical red blood cell will circulate for about 120 days before it is destroyed and excreted. Normally, there are about 5 million red blood cells in every millilitre of human blood.

18. Leukocytes (White Blood Cells) They are far less numerous (about 7,000 cells per millilitre of blood) and much larger (about 12 to 15 micrometres in diameter) than red blood cells. White blood cells contain nuclei, can reproduce, and are generated by the bone marrow.

19. Granular Leukocytes Make up 50-60% of leukocytes Have a life span of 2 to 14 days Contain granules in cytoplasm Neutrophils engulf invading microbes using phagocytosis and protect the body from the effects of those microbes. Eosinophils and basophils, are believed to play a role in allergic reactions.

20. Agranular Leukocytes Make up 30-40% of leukocytes Have a life span of 100 to 200 days Do not have granules in cytoplasm Monocytes can temporarily leave the blood vessels and enter the spaces in between body cells in order to engulf invading microbes. Lymphocytes, produce antibodies, which are "flags" that are attached to foreign particles and invading microbes in order to label them as foreign.

22. When the white blood cell has engulfed the microbe, it produces digestive enzymes to destroy not only the microbe but also itself.

23. Thrombocytes (Platelets) Produced in the bone marrow and do not possess nuclei. Small and irregularly shaped cell fragments. Consist of small amounts of cytoplasm surrounded by a cell membrane. Measure about 2 micrometres in diameter. There are about 150,000 to 400,000 cells per millilitre of blood.

24. They are fragile cells and rupture easily if they encounter a rough surface such as those formed when a blood vessel is broken. When platelets rupture, they release substances that initiate the clotting process. When a blood vessel is broken, it is very important that clotting of the blood occurs in order to prevent the loss of too much blood from that vessel.

25. Dissolved Substances Composed of various chemicals, including dissolved gases (primarily O 2 and CO 2 ). Since most of the oxygen transported by the blood is carried by hemoglobin molecules in red blood cells, only a small amount of oxygen is carried in the plasma itself. The plasma also contains dissolved sugars and inorganic salts like sodium chloride.

26. Waste products of cellular respiration are also carried in the plasma. Various enzymes and hormones are transported in the blood plasma, as are plasma proteins. There are a number of different plasma proteins with a number of different functions. Some help in blood clotting. Some fight infection. Some help to maintain an appropriate pH in the blood and others are carrier molecules.

28. Coagulation The formation of a clot is called coagulation. Coagulation helps when you are injured because it slows blood loss. However, your blood shouldn't clot when it's moving through your body.

30. Types of Clots If blood clots inside your blood vessels, it's called thrombosis. The tendency to clot too much is called hypercoagulation which can be very dangerous. When abnormal clots occur, they usually form inside veins. A clot inside a blood vessel is called a thrombus.

31. A clot that gets stuck in your lungs is called a pulmonary embolus. It keeps blood from getting to your lungs and can be life- threatening. A clot that blocks a blood vessel in the brain can cause a stroke. A clot in a blood vessel in the heart can cause a heart attack. Blood clots can cause some women to have miscarriages.

32. Certain situations or risk factors can make it easier for your blood to clot too much. These situations include the following: Sitting on an airplane or in a car for a long time Having prolonged bed rest (several days at a time) Having surgery Having cancer Being pregnant Using birth control pills

33. Some people are born with an inherited tendency to develop clots. Most of the time, increased clotting happens because the anti- clotting protein in the blood isn't doing its job properly.

35. Blood Groups The most well-known and medically important blood types are in the ABO group. They were discovered Karl Landsteiner in the process of trying to learn why blood transfusions sometimes cause death and at other times save a patient. Landsteiner's rules for the ABO Blood Group: 1.A person does not have antibody to his own antigens 2.Each person has antibody to the antigen he lacks (only in the ABO system)

36. It was discovered in the early 1900s that there are various human blood types and that sometimes they could not be successfully "mixed" in human recipients of transfusions. These blood types are due to the existence of various molecules on the membrane of red blood cells, called glycoproteins.

38. There are many types of glycoproteins but we will focus specifically on three of them that are found on the surface of the red blood cell. These three molecules are referred to as the "A Protein," the "B protein," and the "Rh protein." These molecules have sometimes been called "markers."

39. The word "marker" is used because it emphasizes the fact that the human body recognizes familiar markers and foreign markers. When a foreign marker is detected, the body attacks the cell possessing that marker. In that way, the body recognizes what is foreign and tries to get rid of it. It also recognizes what is not foreign and does not attack it.

40. Such a "marker" on the surface of a cell is called an antigen. An antigen is recognized by the body as either a familiar antigen or as a foreign antigen. Foreign antigens trigger the production of antibodies.

41. Antibodies attach to the foreign antigens and cause a process that leads to the destruction of the foreign cell or particle. So if a person receives a blood transfusion that contains blood with a foreign glycoprotein, that person's body will produce antibodies that will attach to those foreign antigens. As a result, the blood cells will clump in a process called agglutination and the transfusion will not be successful.

42. Agglutination will occur when Antibody A attaches to Antigen A. Agglutination simply means the clumping of particles. antibody antigen

43. The A and B Proteins A person with only the A protein on the red blood cell surface is said to have Type A blood. A person with only the B protein on the red blood cell surface is said to have Type B blood.

44. A person who possesses both A and B proteins on the red blood cell surface has Type AB blood. A person who possesses neither A nor B protein on the red blood cell surface has Type O blood.

45. Antibody A will attack A antigen Antibody B will attack B antigen Antibodies are produced in the bloods plasma. no antibodies will be made

46. Because blood type O can be successfully accepted by donors with any of the four blood types, type O is called the universal donor blood type. Since a person with blood type AB can successfully accept any of the four blood types, type AB is called the universal recipient blood type.

47. A B AB O Universal Donor Universal Recipient

48. The Rh Factor The Rh glycoprotein is another antigen on the surface of red blood cells, also called the Rh Factor. A person who possesses the Rh glycoprotein is said to be "Rh+" and a person who does not possess the protein is said to be "Rh-".

49. With respect to transfusions, the person who is Rh+ is able to accept a transfusion of Rh- blood. However, a person with Rh- blood cannot accept Rh+ blood because the Rh antigen would be foreign to that recipient. They would build antibodies against that antigen and cause the transfusion to be rejected.

50. Rh+Rh- Rh+ blood can receive both + and – blood types. Rh- can only receive – blood types

55. A woman is at risk when she has a negative Rh factor and her partner has a positive Rh factor. This combination can produce a child who is Rh positive. While the mother's and baby's blood systems are separate there are times when the blood from the baby can enter into the mother's system. This can cause the mother to create antibodies against the Rh factor, thus treating an Rh positive baby like an intruder in her body If this happens the mother is said to be sensitized. Fetal Heart Circulation Fetal Heart Circulation

56. Blood Vessels Our blood connects the digestive system to each body cell. It also connects each body cell to the respiratory system. The blood also carries wastes away from every body cell and transports it to organs designed to filter it from the blood and eliminate it from the body.

57. The human circulatory system is made up primarily of one large, muscular pumping organ —the heart —and a series of vessels or tubes that carry the blood. Some of these vessels are large enough to see through the skin and some are microscopic in diameter. These vessels, when considered together as a system, form a network of vessels that effectively bathe all body cells in fluid.

58. Blood is pumped away from the heart so that it can reach distant parts of the body. It then travels back to the heart in order to be pumped once again. The vessels that are specialized to carry blood away from the heart are called arteries. The vessels that are specialized to carry blood back to the heart again are called veins. And the tiny, microscopic vessels that connect arteries to veins are called capillaries.

59. arteriole venule capillary artery vein flow of blood

60. Arteries Strong blood vessels that carry blood that has just been forcefully pumped by the heart. Have thick, muscular walls composed of three layers The outer and the inner layers are made of tough, rigid connective tissue. The middle layer is made of elastic connective tissue and muscle. Arteries carry oxygen-rich blood, with the exception of the pulmonary arteries.

61. Since blood is forcefully pushed through arteries, the diameter of these vessels increases to accommodate the surge of blood. The pulse that you can feel on your wrist or on the side of your neck is actually caused by surges of blood through the arteries in those areas. A period of relaxation follows each surge of blood, clearly distinguishing one beat from the next.

63. Capillaries As blood gets further away from the heart, it enters smaller branches of the arteries called arterioles. These tiny vessels further branch into still smaller vessels called capillaries. The tiniest capillaries are so narrow that they only allow red blood cells to move through them in single file.

64. The exchange of material between the circulatory system and the fluid surrounding the individual cells of the body takes place across the wall of the capillaries. The direction of diffusion of each material is a product of its concentration gradient. Nutrients diffuse out of the blood, while CO2 and other waste materials diffuse in.

65. flow of blood

66. Veins Veins carry blood rich in carbon dioxide (CO 2 ) back to the heart so that it can be oxygenated and pumped again. The only veins that carry oxygen-rich blood are the pulmonary veins. The blood pressure in veins is much lower than that in arteries because the blood is returned to the heart instead of just leaving it.

67. In order to keep the blood moving in the right direction, veins possess valves that allow the blood to move toward, not away from, the heart. The contraction of skeletal muscles also helps to push and squeeze blood back to the heart.

68. At any one time, about 50% of your blood is found in veins; therefore, they act as important reservoirs for blood. During times of stress, such as physical exercise, venous blood flow can be increased; as a result, more blood is available to the body.

70. Varicose Veins Large volumes of blood tend to stretch veins. Pooling of blood over long periods of time can damage valves. If a valve does not work properly, gravity carries the blood to the feet where it pools. Surface veins become larger and begin to bulge forming varicose veins. Prolonged standing, especially with restricted movement increases the pooling of blood.

71. Varicose Veins Varicose Veins

72. The Heart About the size of your fist. Pumps about 70 times per minute and must continue to do so for as long as you are alive. It is a muscle that we do not have conscious control over, its action is considered to be involuntary.

73. The muscle tissue that makes up the heart is called cardiac muscle and does not fatigue easily. The beating of the heart responds to many different changes in the environment; external factors like temperature and exercise affect the beating of the heart.

74. Blood Streams Through the Heart Blood Streams Through the Heart

75. StructureFunction Left atria Receives oxygenated blood returning to the heart from the pulmonary veins Right atria Receives de-oxygenated blood returning to the heart from the superior and inferior vena cava. Left ventricle Receives blood from the left atrium and pumps it to the aorta.

76. Right ventricle Receives blood from the right atrium and pumps it to the pulmonary arteries. Septum Separates the two ventricles, preventing oxygenated and de- oxygenated blood from mixing. Superior vena cava Returns de-oxygenated blood from the head, neck, arm and chest regions of the body to the right atrium.

77. Inferior vena cava Returns de-oxygenated blood from the lower body regions (legs, back, abdomen and pelvis) to the right atrium. Pulmonary arteries Carries de-oxygenated blood from the heart to the lungs. Pulmonary veins Carries oxygen rich blood to the heart from the lungs. Aorta Carries and distributes oxygen-rich blood to the rest of the body.

78. Tricuspid valve Prevents the back flow of blood as it is pumped from the right atrium to the right ventricle. Bicuspid valve (mitral valve) Prevents the back flow of blood as it is pumped from the left atrium to the left ventricle. Semilunar valve (aortic and pulmonary valve) Prevents the back flow of blood as it is pumped from the ventricles.

80. The Heartbeat Every heartbeat is actually made of two beats, one stronger than the other. The two ventricles contract at the same time, sending blood both to the lungs and out to the body (lub). Then the two atria contract at the same time, sending blood into the two ventricles (dub). So each heartbeat is really two beats.

81. The "lub-dub" sound is the sound of the valves in the heart closing after blood has moved through them. The stronger of the two contractions is the ventricular contraction. Contraction of the ventricles is called systole. Contraction of the atria is less forceful and is called diastole.

82. First heart sound, “lub”, occurs when atrioventricular valves close. Second heart sound, “dub”, occurs when semilunar valves close. Tricuspid and mitral valve Normal Heart Sounds Normal Heart Sounds

83. The Cardiac Cycle Cardiac Cycle Animation

84. Fetal Circulation In the human fetus, the lungs are not functional; the placenta substitutes for the lungs as the organ of gas exchange. Oxygenated blood is delivered to the fetus from the placenta by the umbilical vein. This highly oxygenated blood flows into the inferior vena cava, which enters the right atrium. However, deoxygenated blood being returned from the internal organs contaminates the pure placental blood flowing in the inferior vena cava.

85. Fortunately, the volume of placental blood is large, so that the mixture entering the right atrium is relatively well oxygenated. Ordinarily, blood would flow directly from the right atrium into the right ventricle, and, in turn, would leave the heart through the pulmonary trunk to the lungs. This would be a useless course in the fetus since the lungs are inactive.

86. The main volume of the relatively pure blood in the right atrium crosses through a special opening, known as the foramen ovale, into the left atrium. From the left atrium the blood reaches the left ventricle, which pumps the blood into the aorta to be delivered through the systemic system. Thus, the foramen ovale is an important device to ensure that a considerable portion of the oxygenated blood passes directly from the right atrium into the left atrium. Blood that passes from the right atrium to the right ventricle will be directed through a second shunt, called the ductus arteriosus that leads to the aorta. Some of the blood will reach the lungs through the pulmonary trunk, but a greater part arising from the right ventricle will continue through the ductus arteriosus to the aorta.

88. Fetal circulation ceases at birth. When the lungs of the newborn expand with air, pulmonary circulation begins so that there will be an adequate supply of oxygen to the body. Constriction of the ductus arteriosus occurs shortly after birth with the result that the blood leaving the right ventricle no longer bypasses the lungs. Also, the foramen ovale is gradually sealed. In some cases, the foramen ovule fails to close. This results in a condition known as "blue baby". The blue color is the result of the mixture of oxygenated and deoxygenated blood in the atria.

91. Sinoatrial Node (SA Node) Mass of specialized cells that initiate the contraction of the heart muscles of the atria and ventricles. Called the pacemaker because it produces the impulse that starts each heartbeat. Located in the right atrium near entrance of superior vena cava.

92. When the SA node “fires”, the nerve impulse spreads quickly over both atria, causing the atrial muscles to contract. The impulse then reaches a second node of tissue, the atrioventricular node.

93. Atrioventricular Node (AV Node) Located in the septum between the ventricles but in contact with the lower portion of the right atrium. Stimulation of the AV node causes nerve impulses to be sent down the bundle of nerve fibres, known as the Bundle of His. Bundle of His branches into a pair of nerve fibres through the septum and circling around the base of each ventricle.

94. The impulse started in the SA node and picked up by the AV node reaches the muscles of the ventricles and causes them to contract. The heart has special muscle fibres called Purkinje fibres that conduct impulses. The Purkinje fibres form a pathway for conduction of the impulse that ensures that the heart muscle cells contract in the most efficient pattern.

96. Electrocardiograph An electrocardiograph is an instrument that is used to measure electrical activity of the heart. It measures changes in electrical potential across the heart and can detect the contraction pulses that pass over the surface of the heart. The resulting record is called an electrocardiogram (ECG or EKG)

98. An electrocardiogram translates the heart’s electrical activity into line tracings on paper. The spikes and the dips in the line tracings are called waves. The P wave is a record of the electrical activity through the upper heart chambers (atria). The QRS complex is a record of the movement of electrical impulses through the lower heart chambers (ventricles)

99. The ST segment shows when the ventricle is contracting, but no electricity is flowing through it. The ST segment usually appears as a straight, level line between the QRS complex and the T wave. The T wave shows when the lower heart chambers are resetting electrically and preparing for their next muscle contraction.

100. Pacemakers If the natural pacemaker (SA node) ceases to work properly or the electrical pathways in the heart become blocked, the heart may beat too slowly, too quickly or with an irregular beat. Disorders of the regular rhythmic beating of the heart are called arrhythmias.

101. When the natural pacemaker fails to work properly, doctors can implant a small, battery- operated device called an artificial pacemaker to help the heart beat in a regular rhythm. Artificial pacemakers can be permanently implanted into a person's chest or they may be temporary and located outside of the body. Both types use batteries to send electrical impulses to the heart. A wire or electrode is placed next to the heart and transmits small electrical charges to the heart.

102. Most current pacemakers are demand pacemakers which have sensing devices to turn the pacemaker on when the heartbeat falls below a certain level.

103. Blood Pressure The measurement of force applied to artery walls For blood to reach every extremity of your body, it must be pumped out of the heart under considerable pressure. Highest pressure occurs in the aorta and decreases as blood moves away from the heart.

105. Blood pressure readings consist of two numbers. 1 st - Measure of the pressure inside your blood vessels during systole. 2 nd - Measure of the pressure inside your blood vessels during diastole. A typical blood pressure reading would be about 120/80 mmHg (unit of pressure). The "120" is the systolic reading and the "80" is the diastolic reading. Measured using a sphygmomanometer.

106. Hypertension Term used to describe high blood pressure Consistently having a blood pressure reading of at least 140/90. One or both of these numbers can be too high. Can be caused by high stress levels, increased salt intake, or heredity.

107. Without treatment, hypertension can lead to:

108. Factors that Affect Heart Rate and Blood Pressure Heart rate is affected by two primary types of autonomic (automatic) nerves.

109. 1. Sympathetic nerves Causes the heart rate to increase. Nerves fire in times of stress; as a result, blood flow to body tissues increases, enabling the body to better deal with the source of stress. When the heart beats more than 100 times in one minute, or 100 BPM, it is said to be in a condition of tachycardia. When the cause of stress is removed, the heart rate begins to decrease.

110. 2. Parasympathetic nerves Stimulated to fire during times of relaxation. The condition in which the heart beats very slowly is called bradycardia.

111. "Stress" can refer to a number of conditions and situations. Physical exercise is a form of "stress" on the body. When the body perceives a state of emergency, it responds appropriately in order to handle this stress. Some drugs, like caffeine and nicotine, cause tachycardia. Other drugs can cause the heart rate to decrease.

112. Affects of Stress Blood pressure inside vessels increases in response to a greater flow of blood. One result of the firing of the sympathetic nerves is constriction of blood vessels. This constriction causes blood pressure to increase. When the source of stress is removed, the parasympathetic nerves cause blood pressure to drop again.

113. The adrenal glands release adrenaline, a hormone. Adrenaline travels to all of the body organs since it is in the blood. Adrenaline causes the heart muscle to contract more frequently, increasing heart rate.

114. Circulatory Homeostasis: Heart Rate Heart rate must be maintained within acceptable limits. The heart cannot beat too rapidly or too slowly. The appropriate heart rate at any one time depends on a number of factors, including physical activity and stress.

115. Sympathetic and parasympathetic nerves affect how rapidly the heart beats. Adrenaline released by the adrenal glands in times of stress also causes the heart rate to increase.

116. Blood Pressure If the blood pressure gets too high, arterial walls can be weakened. If blood pressure gets too low, the body's ability to transport blood is reduced. If blood pressure drops too low, the brain essentially "turns itself off" causing the person to faint.

117. Special blood pressure sensors are located in the walls of the aorta and the carotid arteries that carry blood to the head. These sensory cells are called baroreceptors because they are sensitive to pressure. If blood pressure is too high, these cells send a nervous message to the brainstem telling it to "turn down" the sympathetic nerves and "turn up" the parasympathetic nerves. As a result, arterioles dilate and blood pressure drops.

118. If the blood pressure is too low, the baroreceptors cause sympathetic nerves to fire so that cardiac output increases and arterioles constrict. As a result, blood pressure rises.

119. Breathing Rate We know that in times of stress or during physical exercise, breathing rate increases. This physiological response occurs along with an increase in blood pressure and an increase in heart rate.

120. Metabolic Waste Products Cannot reach dangerously high levels in the blood. Walls of arterioles are sensitive to carbon dioxide levels. If the level of carbon dioxide in the blood is too high, the smooth muscles in the walls of arterioles relax, causing dilation of those vessels.

121. This increased blood flow carries away potentially toxic metabolic wastes and also supplies the tissue with a greater nutrient supply. As a result, tissues that are very active and therefore produce more metabolic wastes are supplied with a greater blood supply. When the levels of metabolic wastes go down, arteriolar dilation and blood flow both decrease.

122. Cardiovascular Diseases Cardiovascular diseases are defined as diseases and injuries of the cardiovascular system: the heart, the blood vessels of the heart, and the system of blood vessels (veins and arteries) throughout the body and within the brain. Stroke is the result of a blood flow problem in the brain. It is considered a form of cardiovascular disease.

123. The exact number of Canadians who have cardiovascular disease is unknown. It is estimated that one in four Canadians has some form of heart disease, disease of the blood vessels or is at risk for stroke. If this estimate is accurate, approximately eight million Canadians have some sort of cardiovascular disease.

124. Cardiovascular Disease Deaths Cardiovascular disease accounts for the death of more Canadians than any other disease. In 1999 (the latest year for which Statistics Canada has data), cardiovascular disease accounted for 78,942 Canadian deaths. 35% of all male deaths in Canada in 1999 were due to heart diseases, diseases of the blood vessels and stroke. For women, the toll was even higher - 37% of all female deaths in 1999 were due to cardiovascular disease.

125. 54% of all cardiovascular deaths are due to coronary artery disease; 20% to stroke; 16% to other forms of heart disease such as problems with the electrical system of the heart, viral heart infections, and heart muscle disease, and the remaining 10% to vascular problems such as high blood pressure and hardening of the arteries.

126. Arteriosclerosis Arteriosclerosis is a general term for the thickening and hardening of the arteries. Arteriosclerosis comes from two Greek words: athero (meaning gruel or paste) and sclerosis (hardness). In arteriosclerosis, the walls of the arteries have a build-up of plaque, a combination of cholesterol, cellular waste products, calcium and fibrin (a clotting material in the blood). Plaque rupture can trigger the formation of a blood clot. Arteriosclerosis

127. Arteriosclerosis affects large and medium-sized arteries. The type of artery involved and the location of the plaque varies with each person. Researchers are still trying to determine why plaque is "patchy" (i.e., why it doesn't occur consistently throughout the artery but is found only in certain locations). Arteriosclerosis is a slow, progressive disease that may start as early as childhood. People's susceptibility to arteriosclerosis varies with their genetic make-up and their lifestyles.

128. The causes of arteriosclerosis are complex and still not entirely understood. Blood vessels have a thin lining composed of endothelial cells. Many scientists think arteriosclerosis begins when this inner lining becomes damaged. The blood vessel wall reacts to this injury by stimulating various types of cells to grow and reproduce. The result is a progressive thickening of the blood vessel wall.

129. Risk Factors for Arteriosclerosis High levels of LDL cholesterol and triglycerides in the blood; Lipoprotein oxidation, the process whereby cholesterol is modified by elements called "free radicals" and becomes more damaging to the blood vessels; High blood pressure; Smoking. Cigarette smoke greatly aggravates and speeds up the growth of arteriosclerosis in the coronary arteries; Genetics. There appears to be a strong genetic component to arteriosclerosis.

130. A person with arteriosclerosis may remain symptom-free until the disease is far enough advanced to block a significant portion of some important blood vessel. If the blockage occurs in a coronary artery (one which supplies the heart muscle),the result is angina. Angina (angina pectoris is the full medical term) is chest pain. It is sometimes described as "pressure" or "discomfort" rather than pain; it may also radiate to the throat, jaw, back, or arms.

131. Angina usually follows a predictable pattern. Pain generally occurs at about the same point when exercising and/or under emotional stress. The pain usually comes on with activity and/or emotional stress and goes away with rest and/or nitroglycerin within three to five minutes. Angina is a warning signal. It is the heart muscle’s way of telling the body that it is being forced to work too hard and needs to slow down.

132. Arteriosclerosis can cause a heart attack or myocardial infarction in one of two ways. First, it can block coronary arteries to such an extent that little or no blood can get through to the heart. Second, rupture of plaque can trigger the formation of blood clots, which may then block a coronary artery.

133. Heart Attack Warning Signs Pain sudden discomfort or pain that does not go away with rest pain that may be in the chest, neck, jaw, shoulder, arms or back pain that may feel like burning, squeezing, heaviness, tightness or pressure In women, pain may be more vague Shortness of Breath difficulty breathing

134. Nausea indigestion vomiting Sweating cool, clammy skin Fear anxiety denial Arteriosclerosis can also cause a stroke by blocking cerebral blood vessels (those within the brain) or by triggering a clot which then blocks cerebral blood vessels.

136. Arteriosclerosis can be diagnosed using angiography, arteriography or Doppler ultrasound testing. The progress of arteriosclerosis can be significantly slowed by avoiding the risk factors for the disease. Keeping blood pressure within healthy limits, adopting a non-smoking lifestyle, exercising regularly and eating a balanced, low-fat diet will all help control arteriosclerosis.

137. If arteriosclerosis progresses to the point where it is seriously obstructing blood flow in one or more coronary arteries, angioplasty may be recommended. This catheter-based procedure unblocks arteries without major surgery.

138. Traditionally, angioplasty has been used to widen narrowed blood vessels in the heart. The catheter is positioned where a blood vessel has been narrowed by the buildup of plaque (arteriosclerosis). A balloon tip is inflated, which presses against the atherosclerotic plaque and widens the blood vessel.

139. Stenting is similar in many ways to angioplasty. In addition to using a balloon, a wire mesh tube (called a stent) is inserted into the narrowed artery. When the balloon tip is inflated, the stent pops open. The balloon is then removed, leaving the stent in place. The stent helps to prevent the blood vessel from collapsing and re-narrowing. Another option is bypass surgery, which replaces "clogged" arteries with unblocked arteries taken from the patient’s own leg or chest.

140. Aneurysm An aneurysm is a bulging out of part of the wall of a blood vessel. It forms where the wall has weakened, often due to the build-up of plaque. It may also be an inherited condition or a complication of high blood pressure (hypertension). Left untreated, aneurysms may tear or burst (a ruptured aneurysm). Ruptures are very painful events that cause massive internal bleeding. The patient must be treated within minutes in order to have a chance of survival. If an aneurysm bursts in the brain, it could cause a hemorrhagic stroke.

142. If an aneurysm bursts in the chest, there is only a 20 percent chance of survival. Therefore, early diagnosis and treatment are critical. Because aneurysms often produce no symptoms or mild symptoms (e.g., back pain), routine physical examinations are strongly encouraged so that a physician can regularly test for warning signs.

143. Aortic aneurysm. A general condition characterized by the distention, or ballooning out, of part of the wall of the aorta. The aorta is the main artery carrying oxygen-rich blood from the heart to the rest of the body. Typically, the widened part of the aorta is considered to be an aneurysm when it is more than 1.5 times its normal size.

144. Cerebral aneurysm. Also known as a berry aneurysm, this is a bulge in the wall of a blood vessel in the brain (one of the cerebral arteries). A cerebral aneurysm is typically found where the arteries branch at the base of the brain.

145. Cerebral aneurysms occur more commonly in adults than in children and are slightly more common in women than in men, however they may occur at any age. Before an aneurysm ruptures, the individual may experience such symptoms as a sudden and usually severe headache, nausea, vision impairment, vomiting, and loss of consciousness or the individual may be asymptomatic, experiencing no symptoms at all.

146. Onset is usually sudden and without warning. Rupture of a cerebral aneurysm is dangerous and usually results in bleeding in the brain or in the area surrounding the brain, leading to an intracranial hematoma (a mass of blood—usually clotted—within the skull). Brett Michaels

147. Thrombus A thrombus is a blood clot that forms inside a blood vessel or cavity of the heart. The term "thrombosis" refers to the process by which blood clots form.

148. A thrombus is dangerous because it can block a blood vessel partially or entirely, cutting off blood flow to the area supplied by that vessel. A thrombus may form for a variety of reasons, including trauma (injury) or rupture of an atherosclerotic plaque. Risk factors for thrombus formation include arteriosclerosis or other cardiovascular disorders, blood disorders, obesity and heredity.

149. A thrombus will produce different symptoms depending on where it forms. A coronary thrombus will produce chest pain (angina) and may result in a heart attack. A thrombus in the brain will result in a temporary ischemic attack (TIA) or stroke. A thrombus in the limbs may produce a sharp pain in the affected area and a bluish tinge (associated with lack of circulation) below the clot.

150. A thrombus causing stroke or heart attack can be identified on the basis of a physical examination plus an electrocardiogram (ECG) or electroencephalogram (EEG). Doppler ultrasound tests might be used to detect a thrombus in the limbs.

151. Congenital Heart Disease Congenital heart problems are those present at birth. They include defects in the valves and chambers and also circulatory problems. About eight of every 1,000 infants are born with one or more heart or circulatory problems, and about half these cases are serious enough to require treatment. The good news is that congenital defects are being detected earlier than ever - sometimes in the womb - and are being treated with refined medical and surgical methods, including less invasive methods than those used in the past.

152. Causes of Congenital Heart Disease The exact cause of a congenital heart defect is unknown. Although genetic factors seem to play a part, families should be aware that medical researchers cannot predict most cases. Therefore, there's no point in trying to assess genetic "blame" or determine which side of the family "caused" the problem. In addition to genetic factors, certain environmental and behavioral factors have been identified as interfering with the development of the fetus's heart during the first 10 weeks of development.

153. Some conditions that alert a physician to the possibility of congenital heart disease in an infant include: Congenital heart disease in the mother or father. Congenital heart disease in a previous child or other relative. Diabetes in the mother. Rubella (German measles), toxoplasmosis (a protozoa infection transmitted via cat feces), or HIV infection in the mother. The mother's excessive use of alcohol. The mother's use of cocaine or other drugs. The mother's exposure during pregnancy to certain anticonvulsant and dermatological medications.

154. Types of Congenital Heart Disease Abnormalities that impede the flow of blood through the vessels. Heart valves that are malformed, missing, or blocking blood flow. Problems with the structure of the heart that allow blood to flow from one side to the other outside the normal circulatory path. Problems with the connections between the main arteries or veins and the heart.

155. Even though there seem to be both genetic and environmental links to congenital heart disease, a pregnant woman's exposure to one or more of these environmental threats doesn't necessarily mean that her baby will be born with a heart defect. For example, not every mother who contracts rubella during pregnancy delivers a baby with a defective heart. Likewise, unless a specific chromosomal defect has been identified, the fact that an earlier child or close family member had a congenital heart defect does not guarantee that a baby will have a similar problem.

156. Other Heart Conditions Congestive Heart Failure (CHF) usually develops gradually. It is a condition in which the heart does not pump as strongly as it should. The body does not get the right amount of blood and oxygen it needs to work properly. The weakened pumping action can cause a backup of fluid (congestion) in the lungs and other parts of the body. An abnormal buildup of fluid in the lungs is known as pulmonary edema. Without a proper oxygen supply and with congestion, you may feel tired and short of breath at times.

157. Congestive Heart Failure (CHF) has many causes: long-standing impaired blood flow to the heart for some time (this may or may not produce chest pain or angina); heart muscle damage from a previous heart attack; long-standing high blood pressure; a heart valve that is not working properly (heart valve disease); an infection causing inflammation of the heart muscle; excessive use of alcohol or drugs; a disease of the heart muscle itself from an unknown cause.

158. Valvular stenosis is the result of diseases such as rheumatic fever, which causes the opening through a valve in the heart to become so narrow that blood can flow through only with difficulty. The result can be blood damming up behind the valve. Valvular regurgitation occurs when the valves become so worn that they cannot close completely, and blood flows back into the atria or the ventricles. If the blood can flow backward, the efficiency of the cardiac stroke is drastically reduced.

159. A heart murmur is an abnormal heart sound. ("Normal" heart sounds, such as the familiar "LUB-DUB" noise made by the beating heart, are produced by the heart valves opening and shutting. Heart murmurs may be caused by turbulent blood flow in the heart resulting from congenital (present at birth) heart defects. Heart Murmur

160. Some heart murmurs are caused by defective heart valves. Others may be the result of a heart attack. Usually, there are no symptoms associated with a simple heart murmur. If a heart murmur is caused by a heart valve disorder, the patient may experience shortness of breath. Heart murmurs are easily heard by a doctor, listening to heart sounds through a stethoscope. If a heart valve problem is suspected, the patient will be referred for more testing. Diagnostic tests for valve disorders can include a chest x-ray, electrocardiogram (ECG) testing, echocardiograms or cardiac catheterization.

161. Most heart murmurs are quite harmless. They tend to be common in children and disappear when the child grows up. If a heart murmur is the result of a problem with a heart valve, treatment may be necessary. Heart valve problems are often treated with medication. Sometimes, surgical repair or replacement of a damaged valve is required.

162. Artificial Heart Valves Artificial heart valves are man-made or animal- derived valves which can be surgically implanted in a human heart to replace a damaged or diseased valve. Valve replacement surgery dramatically lowers the death rate from valvular disease. Mortality from the surgery is quite low, around 5%, depending upon the age of the patient and his/her overall health and functioning.

163. Each year, there are approximately 4,000 heart valve surgeries in Canada. Human heart valves can be replaced with mechanical valves, or with specially prepared heart valves from human or animal donors (known as bioprosthetic or tissue valves).

164. Mechanical valves (made of metal alloys, carbon and various plastics) are very durable, but can promote the formation of blood clots, which can lead to a heart attack or stroke. To prevent this, patients with mechanical valves must take blood-thinning medication every day for the rest of their lives.

165. Bioprosthetic valves come from two sources: human donors and animals. Valves from animal sources (usually cows or pigs) are very similar to those found in the human heart. They are well tolerated by the body, and do not promote clot formation to the same degree as mechanical valves. On the other hand, bioprosthetic valves from pigs or cows are usually not as durable as the mechanical kind. Human heart valves are well tolerated and tend to last longer than animal valves.

166. Valve Replacement Valve Replacement