Circulatory System And Lymphatic System PPT PDF

Unit 5 CIRCULATORY SYSTEM AND LYMPHATIC SYSTEM  Why study circulation? Multicellular organisms rely on the circulatory system to bring nutrients to and take wastes away from cells In humans, circulation is so important that if the heart stops beating for a few minutes, death res...

Unit 5 CIRCULATORY SYSTEM AND LYMPHATIC SYSTEM  Why study circulation? Multicellular organisms rely on the circulatory system to bring nutrients to and take wastes away from cells In humans, circulation is so important that if the heart stops beating for a few minutes, death results In this unit, we will learn about the heart and how it works, the major vessels of the circulatory system, blood (Immunity), the lymphatic system and disorders UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.1 The Blood Vessels The circulatory system has three types of blood vessels. Arteries: carry blood away from the heart to the capillaries Capillaries: permit exchange of material with the tissues Veins: return blood from the capillaries to the heart TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.1 The Arteries The largest artery in the body is the aorta, which carries O2-rich blood from the heart to other parts of the body. The arterial wall has three layers. Inner layer: endothelium Middle layer: smooth muscle that contracts and relaxes to regulate blood flow and pressure Figure 10.1 Blood vessels. The walls of arteries and veins have three layers. The inner layer is Outer layer: fibrous connective composed largely of endothelium, with a basement membrane that has elastic fibres; the middle layer is tissue smooth muscle tissue; the outer layer is connective tissue (largely collagen fibres). a. Arteries have a thicker wall than veins because TO PREVIOUS they have a larger middle layer than veins. SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.1 Arterioles are small arteries that branch off from an artery (about 2.2 mm in diameter or smaller) Arterioles have three layers. Inner layer: endothelium Middle layer: some elastic tissue but mostly smooth muscle o Smooth muscle contracts: blood vessel constricts, resulting in higher blood pressure o Smooth muscle relaxes: blood vessel relaxes, resulting in lower blood pressure Outer layer: fibrous connective tissue TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.1 The Capillaries Capillaries are narrow microscopic blood vessels that join arterioles to venules. Composed of a single layer of epithelium with a basement membrane Form vast networks (capillary beds) throughout the body (6000m2) TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.1 Only certain capillary beds are open at any given time. o After eating, capillary beds that serve the digestive system are open, and those that serve the muscles are mostly closed o Sphincter muscles relax to open the bed and allow blood flow o Sphincter muscles contract to close the bed and prevent blood flow TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.1 Figure 10.2 Anatomy of a capillary bed. A capillary bed forms a maze of capillary vessels that lies between an arteriole and a venule. When precapillary sphincter muscles are relaxed, the capillary bed is open, and blood flows through the capillaries. When sphincter muscles are contracted, blood flows through a shunt (anastomosis) that carries blood directly from an arteriole to a venule. As blood passes through a capillary in the tissues, it gives up its oxygen. Therefore, blood goes from being O2-rich TO PREVIOUS in the arteriole (red colour) to being O2-poor in the vein (blue colour). SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.1 Exchange of substances takes place across the thin walls of the capillaries. oOxygen and nutrients (such as glucose) diffuse out of the capillary and into the tissue fluid that surrounds cells oWastes (carbon dioxide) diffuse into the capillary oSome water leaves the capillaries, and excess is picked up by lymphatic vessels TO PREVIOUS SLIDE Blood flow through the capillary UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.1 The Veins Veins and venules (small veins) take blood from the capillary beds to the heart. Veins and venules have the same three layers as arteries, but there is less smooth muscle and connective tissue Veins have valves, which allow blood to flow toward the heart when open and prevent blood from flowing backward when closed TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.1 Veins act as a blood reservoir oSince their walls are thinner, they can expand to a greater extent oAbout 70% of blood is in the veins The largest veins in the body are the venae cavae (superior vena cava, inferior vena cava), which deliver O2-poor blood to the heart TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.1 Figure 10.1 Blood vessels. The walls of arteries and veins have three layers. The inner layer is composed largely of endothelium, with a basement membrane that has elastic fibres; the middle layer is smooth muscle tissue; the outer layer is connective tissue (largely collagen fibres). a. Arteries have a thicker wall than veins because they have a larger middle layer than veins. b. Capillary walls are one-cell-thick endothelium. c. Veins are generally larger in diameter than arteries, so collectively, veins have a TO PREVIOUS larger holding capacity than arteries. d. Light micrograph of an artery and a vein. SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Blood Blood is a liquid connective tissue that has many different functions. Transports nutrients, wastes, and hormones Regulates body temperature by dispersing body heat Regulates blood pressure Protects the body against invasion by disease-causing pathogens Clotting mechanisms protect the body against loss of blood. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Composition of Blood Blood separates into three layers when centrifuged. Upper layer: plasma (liquid portion of blood) Lower layers: formed elements (white blood cells, platelets, red blood cells) Figure 10.3 Composition of blood. When blood is collected into a test tube containing an anticoagulant to prevent clotting and then centrifuged, it consists of three layers. The transparent straw-coloured or yellow top layer is the plasma, the liquid portion of the blood. The thin, middle buffy coat layer consists TO PREVIOUS of leukocytes and platelets. The bottom layer contains the erythrocytes. SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Plasma Plasma contains a variety of inorganic and organic substances dissolved or suspended in water. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Plasma also contains plasma proteins, which have many functions: Transport: albumin transports bilirubin; lipoproteins transport cholesterol Blood clotting: fibrinogen Fighting infection: antibodies Maintaining blood volume: plasma proteins are too large to leave the capillaries − Blood in capillaries has a higher solute concentrate than tissue fluid, causing water to diffuse in TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 The Red Blood Cells Red blood cells (erythrocytes) are manufactured in the red bone marrow of the skull, ribs, vertebrae, and ends of the long bones. They transport oxygen and carbon dioxide in the blood. TO PREVIOUS SLIDE RBC UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Mature red blood cells have no nuclei and are biconcave. Only live about 120 days (possibly due to lack of nuclei) and are destroyed in the liver and spleen Biconcave shape increases flexibility (for moving through capillary beds) and surface area (for diffusion of gases) Contain hemoglobin, a respiratory pigment that carries oxygen o Iron in hemoglobin acquires oxygen in the lungs and gives it up in the tissues TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Figure 10.4 Physiology of red blood cells. a. Red blood cells move in single file through the capillaries. b. Each red blood cell is a biconcave disk containing many molecules of hemoglobin, the respiratory pigment. c. Hemoglobin contains four polypeptide chains (purple). There is an iron-containing heme group in the centre of each chain. Oxygen combines loosely with iron when hemoglobin is oxygenated. Oxyhemoglobin is bright red, and deoxyhemoglobin is a dark maroon colour. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Anemia is a common blood disorder that results in a tired, rundown feeling. Anemia has three basic causes: Decreased production of red blood cells Loss of red blood cells from the body Destruction of red blood cells within the body Most common type of anemia: iron-deficiency anemia Caused by decreased production of red blood cells due to a diet that lacks adequate iron TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 The White Blood Cells White blood cells (leukocytes) are usually larger than red blood cells, have a nucleus, lack hemoglobin, and appear translucent without staining. They fight infection and play a role in developing immunity. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Figure 10.5 Micrograph of the Formed Elements. The formed elements include red blood cells, different types of white blood cells, and platelets. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 White blood cells can be divided on the basis of structure into granular leukocytes and agranular leukocytes: Granular leukocytes Neutrophils Eosinophils Basophils Agranular leukocytes Monocytes Lymphocytes TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Granular leukocytes Granular leukocytes are filled with spheres that contain enzymes and proteins that help white blood cells defend against microbes. Neutrophils: phagocytize pathogens Eosinophils: phagocytize antigen- antibody complexes and allergens Basophils: release histamine to promote blood flow to injured tissues TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Agranular leukocytes Agranular leukocytes include cells that can phagocytize pathogens and cells that are involved in specific immunity. Monocytes: largest white blood cells; differentiate into phagocytic dendritic cells and macrophages Lymphocytes: o B lymphocytes (B cells): produce antibodies o T lymphocytes (T cells): helper T cells regulate the responses of other cells; cytotoxic T cells kill other cells TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 White Blood Cells and Disease The number of white blood cells increases or decreases beyond normal if disease is present. Neutrophils: increase in response to bacterial infections B cells: increase in response to infectious mononucleosis T cells: a low number of T cells indicates if an HIV-infected person has AIDS A large number of abnormal white blood cells is characteristic of leukemia, a form of cancer TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Figure 10.6 Macrophage (red) engulfing bacteria. Monocyte-derived macrophages are the body’s scavengers. They engulf microbes and debris in the body’s fluids and tissues, as illustrated in this colourized scanning electron micrograph. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 The Platelets and Blood Clotting Platelets (also called thrombocytes) result from fragmentation of large cells called megakaryocytes in the red bone marrow. Platelets are involved in blood clotting (coagulation). There are at least 12 clotting factors in the blood that help platelets in the formation of a blood clot (examples: prothrombin, fibrinogen). TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Blood Clotting The process of clotting begins when a blood vessel is damaged. Platelets clump at the site of damage and form a plug to partially seal the leak. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Blood Clotting Platelets and damaged tissue release prothombin activator, which converts prothrombin (a clotting factor) to thrombin in the presence of calcium ions. Thrombin acts as an enzyme on fibrinogen (a clotting factor) to form fibrin threads. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Blood Clotting Fibrin threads wind around the platelet plug and trap red blood cells to form the framework of the clot. When blood vessel repair is initiated, plasmin (an enzyme) destroys the fibrin framework and restores the fluidity of the plasma. TO PREVIOUS SLIDE Blood clotting or separation... UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Blood Clotting If blood is allowed to clot in a test tube, a yellowish material, called serum, develops above the clotted material TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Figure 10.7 Blood clotting. a. A scanning electron micrograph of a blood clot shows red blood cells caught in the fibrin threads. b. Platelets and damaged tissue cells release prothrombin activator, which acts on prothrombin in the presence of Ca2+ (calcium ions) to produce thrombin. Thrombin acts on fibrinogen in the presence of Ca2+ to form fibrin threads. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Hemophilia: A Blood Clotting Disorder Hemophilia is a group of inherited clotting disorders caused by a deficiency in a clotting factor. Hemophilia A: 90% of all hemophilia cases Occurs frequently in males since the faulty gene is on the X chromosome Individuals with hemophilia are more prone to bleeding Bleeding in the muscles can lead to nerve damage Bleeding into the brain can lead to neurological damage or death Individuals require frequent blood transfusions or injections of the deficient clotting factor TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Bone Marrow Stem Cells A stem cell is a cell that is ever capable of dividing and producing new cells that go on to differentiate into particular types of cells. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Figure 10.8 Blood cell formation in red bone marrow. Multipotent stem cells give rise to two specialized types of stem cells. The myeloid stem cells give rise to still other cells, which become red blood cells, platelets, and all the white blood cells except lymphocytes. The lymphoid stem cells give rise to lymphoblasts, which become lymphocytes. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Multipotent stem cells in red bone marrow have the potential to give rise to other stem cells for the various formed elements. Can also differentiate into other cells (liver, bone, fat, cartilage, heart, neurons) A patient’s own bone marrow stem cells (adult stem cells) could be used to treat diabetes, heart disease, liver disease, or brain disorders Some researchers prefer using embryonic stem cells since they may be more likely to become any type of cell o Can be collected from unused embryos in fertility clinics, or umbilical cord blood TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Capillary Exchange Fluid in the blood is called plasma. When blood reaches a capillary, the movement of fluid in the blood through the capillary wall is controlled by: Osmotic pressure (causes water to move from the tissue fluid to the blood) Blood pressure (causes water to move from blood to tissue fluid) TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Figure 10.9 Capillary exchange in the systemic circuit. At the arterial end of a capillary (left) the blood pressure is higher than the osmotic pressure; therefore, water tends to leave the bloodstream. In the midsection, molecules, including oxygen and carbon dioxide, follow their concentration gradients. At the venous end of a capillary (right), the osmotic pressure is higher than the blood pressure; therefore, water tends to enter the bloodstream. Notice that the red blood cells and the plasma proteins are too large to exit a capillary. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Arterial End of Capillary Blood pressure is higher than osmotic pressure of blood Water exits capillary Midway Along the Capillary Blood pressure and osmotic pressure cancel each other out No net movement of water Solutes diffuse according to concentration gradient o Nutrients and oxygen diffuse out of the capillary; wastes and carbon dioxide diffuse into the capillaries Small substances leaving capillaries contribute to tissue fluid TO PREVIOUS SLIDE Arterial side UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Venous End of Capillary Osmotic pressure is greater than blood pressure Water moves into capillary Excess tissue fluid is collected by lymphatic capillaries, where it becomes lymph Figure 10.10 Lymphatic capillaries. A lymphatic capillary bed (shown here in green) lies near a blood capillary bed. When lymphatic capillaries take up excess tissue fluid, it becomes lymph. TO PREVIOUS SLIDE VENUS END Blood donation In Canada, more than 2000 units of blood are needed every day One unit = 450 mL A single donation can save up to three lives but only 3.5% of eligible Canadians donate blood. No substitute for human blood … SO DONATE!!!! UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.3 The Human Heart The heart is a muscular organ about the size of a fist. Myocardium: the major portion of the heart; consists of cardiac muscle tissue Pericardium: a thick membrane within which the heart lies; secretes lubricating liquid Endocardium: the inner surface of the heart; a membrane composed of connective and endothelial tissue TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.3 Structure of the Heart The septum separates the heart into a right side and a left side. The heart has four chambers: Two upper, thin-walled atria o Atria fill with blood returning from the body and lungs Two lower, thick-walled ventricles o Ventricles receive blood from atria and pump it out to body and lungs TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.3 Structure of the Heart The heart has four valves that direct the flow of blood and prevent its backward movement. Two atrioventricular valves that are supported by strong fibrous strings called chordae tendineae o tricuspid valve: the valve on the right side o bicuspid (mitral valve): the valve on the left side Two semilunar valves o pulmonary semilunar valve: lies between right ventricle and pulmonary trunk o aortic semilunar valve: lies between the left ventricle and aorta TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.3 Figure 10.12 Internal view of the heart. a. The heart has four valves. When the atrioventricular valves open, blood passes from the atria to the ventricles, and when the semilunar valves open, blood passes out of the heart. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.3 Figure 10.11 External heart anatomy. a. The venae cavae and the pulmonary trunk are attached to the right side of the heart. The aorta and the pulmonary veins are attached to the left side of the heart. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.3 Figure 10.11 External heart anatomy. b. The coronary arteries and cardiac veins pass through cardiac muscle. The coronary arteries bring oxygen and nutrients to cardiac cells, which derive no benefit from blood coursing through the heart. The cardiac veins drain blood into the right atrium. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.3 Path of Blood through the Heart The superior vena cava and the inferior vena cava, which carry O2-poor blood, enter the right atrium. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.3 The right atrium sends blood through the tricuspid valve to the right ventricle. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.3 The right ventricle sends blood through the pulmonary semilunar valve into the pulmonary trunk and through the two pulmonary arteries to the lungs (where gas exchange occurs) TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.3 Four pulmonary veins, which carry O2-rich blood, enter the left atrium. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.3 The left atrium sends blood through the bicuspid valve to the left ventricle. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.3 The left ventricle sends blood through the aortic semilunar valve into the aorta and on to the rest of the body. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.3 The heart is a double pump. o Right ventricle sends blood into the lungs o Left ventricle sends blood into the rest of the body − A stronger pump, since it has to pump blood to the body Cardiac output is the volume of blood that the left ventricle pumps per minute. o Cardiac output is about 5.25 L of blood per minute in a person with an average heart rate of 70 beats per minute The pulse is a wave effect that passes down the walls of the arteries when the aorta expands and recoils with each ventricular contraction; can be used to determine heart rate TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.3 The Heartbeat - LUB-DUPP Each heartbeat is called a cardiac cycle. When a heart beats: The two atria contract at the same time, and the ventricles are relaxed and fill with blood (the LUB part) Then, the two ventricles contract at the same time (the DUPP part) Then, all the chambers relax TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.3 Figure 10.13 Generation of heart sounds during the cardiac cycle. a. When the atria contract, the ventricles are relaxed and filling with blood. b. When the ventricles contract, the atrioventricular valves close, preventing blood from flowing back into the atria and producing the “lub” sound of the heartbeat. c. After the ventricles contract, the “dub ” sound of the heartbeat results from the closing of the semilunar valves to prevent arterial blood from flowing back into the ventricles. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.3 The heart beats about 70 times a minute; each heartbeat is 0.85 s. Systole is the contraction of the heart muscle Diastole is the relaxation of the heart muscle TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.3 Intrinsic Control of Heartbeat The heart is able to contract and relax rhythmically due to the presence of nodal tissue, a type of cardiac muscle. Nodal tissue is located in two areas:: SA (sinoatrial) node: initiates the heartbeat and sends out an impulse every 0.85 s; also called the pacemaker AV (atrioventricular) node: transmits an impulse through specialized cardiac muscle fibres called the atrioventricular bundle (AV bundle), which send the signal to Purkinje fibres TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.3 Figure 10.14 Conduction system of the heart. a. The SA node sends out a stimulus (black arrows), which causes the atria to contract. When this stimulus reaches the AV node, it signals the ventricles to contract. Impulses pass down the two branches of the atrioventricular bundle to the Purkinje fibres, and thereafter the ventricles contract. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.3 Extrinsic Control of Heartbeat The body also has extrinsic ways to regulate the heartbeat. Medulla oblongata (portion of the brain that controls internal organs) Can alter heartbeat by the autonomic nervous system o Parasympathetic: decreases SA and AV nodal activity when inactive o Sympathetic: increases SA and AV nodal activity when active Epinephrine and norepinephrine (hormones) Released by the adrenal medulla Heart pumps faster and stronger due to sympathetic stimulation and release of epinephrine and norepinephrine TO PREVIOUS SLIDE ECG UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.3 The Electrocardiogram An electrocardiogram (ECG) is a recording of the electrical changes that occur in the myocardium during a cardiac cycle. Figure 10.14 Conduction system of the heart. b. A normal ECG usually indicates that the heart is functioning properly. The P wave occurs just before atrial contraction; the QRS complex occurs just before ventricular contraction; TO PREVIOUS and the T wave occurs when the ventricles are recovering from contraction. SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.3 Different types of abnormalities, known as arrhythmias can be detected by an ECG Atrial fibrillation (AF): multiple, chaotic impulses are generated from the AV node, causing an irregular, fast heartbeat Ventricular fibrillation (VF): uncoordinated contraction of the ventricles; can occur after a heart attack, injury, or drug overdose o Heart in VF is not pumping blood and must be defibrillated by applying an electrical current to re- establish heartbeat o Automatic external defibrillators(AEDs) can be used to administer an electrical current to the chest TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.3 Figure 10.14 Conduction system of the heart. b. A normal ECG. c. Ventricular fibrillation produces an irregular electrocardiogram due to irregular stimulation of the ventricles. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.4 The Vascular Pathways The circulatory system includes two circuits. Pulmonary circuit: circulates blood through the lungs Systemic circuit: circulates blood to the body tissues TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.4 Figure 10.15 Path of blood. This symbolic and not-to-scale drawing shows the path of blood in the pulmonary and systemic circuits. The pulmonary arteries and veins take blood from the right (blue) to the left (red) side of the heart. Tracing blood from the digestive tract to the right atrium in the systemic circuit involves the hepatic portal vein, the hepatic vein, and the inferior vena cava. The blue-coloured vessels carry O2-poor blood, and the red-coloured vessels carry O2-rich blood; the arrows indicate the direction of blood flow. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.4 The Pulmonary Circuit Pulmonary circuit: circulates blood to lungs Blood from all regions of the body first collects in the right atrium. Blood passes into the right ventricle, which pumps it into the pulmonary trunk. Pulmonary trunk divides into right and left pulmonary arteries, which branch into arterioles. Arterioles take blood to the pulmonary capillaries, where gas exchange occurs. Blood passes through pulmonary venules, which lead to pulmonary veins that enter the left atrium. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.4 The Systemic Circuit Systemic circuit: circulates blood to body tissues. The aorta and venae cavae serve as the major pathways for blood in the systemic circuit TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.4 The path of systemic blood to any organ in the body begins in the left ventricle. Trace the path of blood to and from the legs: left ventricle → aorta → common iliac artery → femoral artery → leg capillaries → femoral vein → common iliac vein → inferior vena cava → right atrium Figure 10.16 Major arteries (red) and veins (blue) of the systemic circuit. This representation of the major blood vessels of the systemic circuit shows how the systemic arteries and veins are arranged in the body. The superior and inferior venae cavae take their names from their relationship to which organ? TO PREVIOUS SLIDE You Try.. You should be able to describe the path of blood to the kidneys You should also be able to compare and contrast the composition of blood between any two vessels (e.g., hepatic vein and pulmonary artery). What is pulse? PULSE: the alternate expanding and recoiling of an arterial wall that can be felt in any artery that runs near the surface of the body. Radial artery in wrist, carotid artery in neck are common places to check. Pulse rate indicates the rate of heartbeat. UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.4 Blood Pressure As blood passes through the blood vessels in the body, it exerts pressure against the vessel walls (blood pressure). Systolic pressure: results from blood being forced into arteries when ventricles contract (ventricular systole) Diastolic pressure: results from pressure in the arteries when ventricles fill with blood (ventricular diastole) o Blood pressure can be measured with a sphygmomanometer, which has a pressure cuff that determines the amount of pressure required to stop the flow of blood through an artery o Expressed in millimetres of mercury as a fraction of systolic pressure over diastolic pressure (e.g., 120/80 mm Hg) TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.4 Blood pressure decreases as blood flows from the aorta into the arteries, arterioles, and capillaries. Blood is under minimal pressure in capillaries since capillaries have a high total cross-sectional area. Figure 10.17 Blood velocity and blood pressure. In capillaries, blood is under minimal pressure and has the least velocity. Blood pressure and velocity drop off because capillaries have a greater total cross-sectional area than arterioles. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.4 Blood pressure in the veins is low. Valves prevent the backward flow of blood in veins, and muscle contraction is sufficient to move blood toward the heart. Figure 10.18 Cross section of a valve in a vein. a. Pressure on the walls of a vein, exerted by skeletal muscles, increases blood pressure within the vein and forces the valve open. b. When external pressure is no longer applied to the vein, blood pressure decreases, and back pressure forces the valve closed. Closure of the valve prevents the blood from flowing in the opposite direction. TO PREVIOUS SLIDE Differences between Fetal and Adult Systems Heart develops in 3rd and 4th weeks in uterus. At end of 8 weeks, the embryo’s organ systems, including heart, are functioning. During fourth month, fetal heartbeat is loud enough to be heard with stethoscope. However, the fetal circulatory system can’t be the same as the adult, if you stop to think about it. The fetus, first of all, can’t breathe air inside the womb, so sending blood to the lungs won’t do much good. Likewise, the fetus must get all its nutrients from Mom, as well as let her take care of its wastes. Obviously, some serious plumbing problems must be solved. To solve these problems, the fetus has some FEATURES not present in adults UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.5 Fetal Circulation The fetus has circulatory features not present in adult circulation. These are necessary since the lungs are not functional in the fetus. Blood passes directly from the right atrium to the left atrium through the foramen ovale between the atria. Any blood that does not enter the right ventricle and is pumped into the pulmonary trunk is shunted into the aorta by the ductus arteriosus. Umbilical arteries take fetal blood to the placenta, where the exchange of gases and nutrients between maternal blood and fetal blood takes place. The umbilical vein then carries the nutrient and O2-rich blood to the fetus. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.5 Figure 10.19 Fetal circulation. The lungs are not functional in the fetus, and the blood passes directly from the right atrium to the left atrium or from the right ventricle to the aorta. The umbilical arteries take fetal blood to the placenta, and the umbilical vein TO PREVIOUS returns fetal blood from the placenta. SLIDE PATH OF BLOOD THROUGH FETUS 1. Begin with blood collecting in Right Atrium 2. From there, blood can go into Left Atrium through Oval opening plus into Right Ventricle through atrioventricular valve. 3. Right Ventricle to Pulmonary Artery. Most of blood will go through arterial duct into aorta. 4. Aorta to tissue. Umbilical arteries lead to placenta, where exchange of gases and nutrients take place. 5. Umbilical vein carries O2-rich blood. It enters the venous duct, passes through liver. 6. Venous duct joins with inferior venae cava (it mixes here with deoxygenated blood) and this mixed blood goes back to the back to heart. UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.5 Structure and Function of the Placenta The placenta is attached to the uterine wall by the allantois and chorionic villi. Functions only before birth; becomes part of the afterbirth when child is born Involved in gas, nutrient, and waste exchange between the fetal and maternal circulatory systems Umbilical cord contains the umbilical arteries and vein, which transport waste to the placenta, and take oxygen and nutrients to the fetal circulatory system TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.5 Figure 10.20 The Placenta. At the placenta, an exchange of molecules between fetal and maternal blood takes place across the walls of the chorionic villi. Oxygen and nutrient molecules diffuse into the fetal blood, TO PREVIOUS and carbon dioxide and urea diffuse out of the fetal blood. SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.6 The Lymphatic System The lymphatic system consists of lymphatic vessels and the lymphoid organs. It is closely associated with the circulatory system. The lymphatic system has three main functions: Lymphatic capillaries absorb excess tissue fluid and return it to the bloodstream Lymphatic capillaries absorb fats from the digestive tract and transport them to the bloodstream Lymphoid organs defend the body against disease TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.6 Figure 10.21 Lymphatic system. Lymphatic vessels drain excess fluid from the tissues and return it to the circulatory system. Lymphatic vessels, like circulatory veins, have valves to prevent backward flow. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.6 Lymphatic Vessels Lymphatic vessels form a one-way system that begins with the lymphatic capillaries. Lymphatic capillaries (tiny, closed-ended vessels) absorb excess tissue fluid called lymph. Tissue fluid contains water, solutes (nutrients, electrolytes, oxygen), and cellular products (hormones, enzymes, wastes) TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.6 Movement of Lymph in Lymphatic Vessels The lymphatic capillaries join to form lymphatic vessels that merge before entering one of two ducts: Thoracic duct: returns lymph collected from the left side of the body into the left sub clavian vein Right lymphatic duct returns lymph collected from the right side of the body into the right sub clavian vein TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.6 Movement of Lymph in Lymphatic Vessels Lymph percolates through various lymph nodes, where foreign material can be recognized by the immune system Movement of lymph in the lymphatic capillaries is dependent on skeletal muscle contraction One-way valves in the vessels prevent lymph from flowing backward TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.6 Edema Edema is localized swelling caused by the accumulation of tissue fluid that has not been collected by the lymphatic system. Occurs if too much tissue fluid is made and/or if not enough is drained away Can lead to tissue damage and death TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.6 Lymphoid Organs Lymphoid organs contain large numbers of lymphocytes (white blood cells involved in adaptive immunity). There are two types of lymphoid organs: Primary lymphoid organs: red bone marrow and thymus, where lymphocytes develop and mature Secondary lymphoid organs: lymph nodes and spleen, where lymphocytes become activated TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.6 Figure 10.22 The lymphoid organs. The thymus (a) and red bone marrow (b) are the primary lymphoid organs. Blood cells, including lymphocytes, are produced in red bone marrow. B cells mature in the bone marrow. T cells mature in the thymus. The lymph nodes (c) and the spleen (d) are secondary lymphoid TO PREVIOUS SLIDE organs. Lymph is cleansed in the nodes, and blood is cleansed in the spleen. UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.6 Primary Lymphoid Organs Red bone marrow Contains a network of connective tissue fibres, along with stem cells that can divide and produce blood cells Lymphocytes begin development in the bone marrow o B lymphocytes (B cells) begin in bone marrow and then migrate to secondary lymphoid organs to mature o T lymphocytes (T cells) begin in bone marrow and then migrate to the thymus, where they mature and differentiate TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.6 Primary Lymphoid Organs Thymus Connective tissue divides the thymus into lobules, which are filled with T cells and supporting cells Lobules are lined with epithelial cells that secrete hormones called thymosins, which are involved in the differentiation of T cells T cells that react to the body’s own cells undergo apoptosis (programmed cell death) T cells that leave the thymus can react to foreign molecules TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.6 Secondary Lymphoid Organs Spleen Consists of blood vessels and sinuses where macrophages remove old and defective blood cells Also contains small areas of lymphoid tissue, where lymphocytes can react to foreign invaders in the blood May be surgically removed due to trauma or disease, however the body becomes more susceptible to certain types of infections TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.6 Secondary Lymphoid Organs Lymph nodes Occur along lymphatic vessels Connective tissue divides nodes into nodules, each of which contain B cells, T cells, and a sinus As lymph passes through the sinuses, macrophages engulf pathogens in the lymph Cancer cells can enter the lymph nodes and lymphatic vessels and move through to other regions of the body, where they produce secondary tumours (metastasis) TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.7 Innate and Adaptive Immunity The lymphatic system works with the immune system to protect the body from pathogens, toxins, and other invaders. Immunity is a condition where the body is protected from various threats (pathogens, toxins, cancer cells). There are two main types of immunity. Innate immunity: Fully functional without previous exposure to substances Adaptive immunity: Initiated and amplified after specific recognition of substances TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.7 Innate Immunity Mechanisms of innate immunity can be divided into at least four types: Physical and chemical barriers Inflammatory response Phagocytes and natural killer cells Protective proteins TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.7 Physical and Chemical Barriers Physical barriers Skin and mucous membranes lining the respiratory, digestive, and urinary tracts are physical barriers to pathogens Chemical barriers Oil glands in the skin secrete chemicals that weaken or kill certain bacteria The acidic pH of the stomach kills many types of bacteria or inhibits their growth Bacteria that reside in the intestine and other areas remove nutrients and block binding sites that could be used by pathogens TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.7 Inflammatory Response Inflammatory response A series of events that is initiated when there is damage to tissues by physical trauma, chemical agents, or pathogens Inflamed areas have four signs: redness, heat, swelling, pain o Mostly due to capillary changes in the damaged area At least three types of cells in the skin and connective tissue play a role in the inflammatory response: o Mast cells o Macrophages o Dendritic cells TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.7 Figure 10.23 Inflammatory response. Due to capillary changes in a damaged area and the release of chemical mediators, such as histamine by mast cells, an inflamed area exhibits redness, heat, swelling, and pain. The inflammatory reaction can be accompanied by other reactions to the injury. Macrophages and dendritic cells, present in the tissues, phagocytize pathogens, as do neutrophils, which squeeze through capillary walls from the blood. Macrophages and dendritic cells release cytokines, which stimulate the inflammatory and other immune reactions. A blood clot can form to seal a TO PREVIOUS break in a blood vessel. SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.7 Inflammatory Response Mast cells Reside in the skin, lungs, and intestinal tract Respond to damage by releasing histamine o Histamine causes capillaries in the area to dilate and become more permeable, allowing fluids to escape to tissues and cause swelling o Swollen area stimulates free nerve endings, causing pain o Increased blood flow causes skin to redden and warm TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.7 Inflammatory Response Macrophages and Dendritic Cells Both are phagocytic cells Release various pro inflammatory cytokines, which are chemical messengers that influence other immune cells o Interleukin-8: attracts other immune cells to the scene o Colony-stimulating factor: causes bone marrow to produce more white blood cells TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.7 Phagocytes and Natural Killer Cells Phagocytes Engulf pathogens into an endocytic vesicle, which fuses with a lysosome in the cell; pathogen is destroyed by compounds in the lysosome Includes neutrophils and monocytes o Neutrophils: the first white blood cells to enter an inflamed area; may accumulate to form pus o Monocytes: migrate from blood and differentiate into macrophages in tissues if inflammatory reaction continues TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.7 Phagocytes and Natural Killer Cells Natural killer (NK) cells Large, granular cells that kill some virus-infected and cancer cells by cell-to-cell contact NK cells induce target cells to undergo apoptosis o Seek out and kill cells that lack a type of “self” molecule, called MHC-I (major histocompatibility class I), on their surface o Some virus-infected and cancer cells lack MHC-I, which makes them susceptible to destruction by NK cells TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.7 Adaptive Immunity Adaptive immunity is activated when innate defences fail to prevent an infection. The adaptive immune system recognizes, responds to, and usually eliminates antigens from the body. Antigens: any molecules that stimulate an adaptive immune response Adaptive defences take 5 to 7 days to become fully activated and last for many years TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.7 The adaptive immune system depends on the activity of B cells and T cells. Both cells recognize antigens because they have specific antigen receptors Each lymphocyte has only one type of receptor Large diversity of antigen receptors on B and T cells o There are specific B cells and/or T cells for almost any possible antigen TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.7 B Cells and Antibody-Mediated Immunity Defence by B cells (antibody-mediated immunity) B cells are activated in a lymph node or the spleen, when their receptors bind to specific antigens Cytokines secreted by T cells stimulate B cells to divide o Most cells become plasma cells, which secrete antibodies − Antibodies are the secreted form of the receptor of the B cell that was activated o Some cells become memory B cells, which allow for long- term immunity − If the same antigen enters again, memory B cells divide and give rise to more plasma cells that can produce the antibody against the antigen TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.7 B Cells and Antibody-Mediated Immunity Antibody Structure Antibodies are also called immunoglobulins (Ig), which are Y-shaped molecules with two arms made of polypeptides o Heavy (long) polypeptide chain o Light (short) polypeptide chain o C (constant) region: set sequence of amino acids o V (variable) region: amino acid sequence varies between antibodies; forms the antigen-binding site TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.7 Figure 10.24 Structure of an antibody. a. An antibody contains two heavy (long) polypeptide chains and two light (short) chains arranged so that there are two variable regions, where a particular antigen is capable of binding with an antibody (V = variable region, C = constant region). The shape of the antigen fits the shape of the binding site. b. Computer model of an antibody molecule. The antigen combines with the two side branches. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.7 B Cells and Antibody-Mediated Immunity Antigens combine with an antibody at the antigen-binding site in a lock-and-key manner Antigen-antibody reactions can result in immune complexes (antigens combined with antibodies) o Immune complexes may mark the antigens for destruction by a neutrophil or macrophage o Antibodies can “neutralize” toxins by preventing them from binding to cells TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.8 Circulatory System Disorders Circulatory system disorders are also known as cardiovascular disease (CVD). CVD is the leading cause of death in most Western countries Examples of CVD include: Atherosclerosis Hypertension Heart Valve Disease Stroke, Heart Attack, and Aneurysm TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.8 Atherosclerosis Atherosclerosis is the accumulation of soft masses of fatty materials (e.g., cholesterol) beneath the inner linings of arteries. Deposits of these materials are called plaque Plaque narrows arteries by protruding into the blood vessel; this results in restricted blood flow Plaque can also cause platelets to adhere to the arterial wall, forming a clot o If the clot remains stationary, it is called a thrombus o If the clot dislodges, it is called an embolus o Thromboembolism is a clot that has been carried in the blood and has become lodged in a blood vessel TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.8 Figure 10B Coronary arteries and plaque. Atherosclerotic plaque is an irregular accumulation of cholesterol and fat. When plaque is present in a coronary artery, a heart attack is more likely to occur because of restricted blood flow. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.8 Hypertension Hypertension is high blood pressure. Under the age of 45 years, blood pressure above 130/90 mm Hg is considered abnormally high Called “the silent killer” because it may not be detected until a stroke or heart attack occurs Occurs secondary to a narrowing of arteries due to atherosclerosis o Narrowed arteries cause an increase in blood pressure, since more force is needed to move blood through the blood vessels Treatment involves vasodilators (which dilate blood vessels) and diuretics (which decrease blood volume by increasing urine) TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.8 Heart Valve Disease Heart valve disorders result in the backflow of blood and range from mild to severe. Heart valves can be malformed at birth, or they can degenerate due to age or infections Result from narrowing (stenosis) of the aortic valve opening, or from mitral valve prolapse (abnormally thickened leaflets of the mitral valve protrude into the left ventricle) Treatment involves repair of faulty valves in open-heart surgery or replacement with artificial valves or valves from an animal or deceased human TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.8 Stroke, Heart Attack, Aneurysm Stroke Occurs when an arteriole in the brain bursts or is blocked by an embolus (a clot that has been dislodged) Results in lack of oxygen (due to impaired blood flow) to the brain, causing a portion of the brain to die Paralysis or death can result Symptoms of stroke include numbness in the hands or face, difficulty speaking, or temporary blindness TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.8 Heart Attack When a coronary artery becomes partially blocked, angina pectoris occurs, resulting in a squeezing or burning sensation in the chest When a coronary artery is completely blocked, a portion of the heart muscle dies due to lack of oxygen, and a heart attack (myocardial infarction) occurs Treatment includes vasodilators (nitroglycerin) to dilate blood vessels TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.8 Aneurysm Occurs when there is a ballooning of a blood vessel, most often the abdominal aorta or the arteries leading to the brain Atherosclerosis and hypertension can weaken the wall of the artery to the point that an aneurysm develops If the aorta bursts, about 50% of victims die before reaching the hospital Treatment involves replacing the damaged or diseased portion of the vessel with a synthetic graft TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.8 Treatment for Cardiovascular Disorders Coronary Bypass Operations Involves grafting arteries to bypass an obstructed coronary artery A segment from another blood vessel in the body is stitched to one end of the aorta; the other end is stitched to a coronary artery past the point of obstruction Figure 10.26 Bypassing blocked coronary arteries. This is a 3-D scan of the heart of a patient who received a triple bypass operation. The surgeon has bypassed two blocked arteries using vessels removed from another part of the body and used an existing artery TO PREVIOUS that branches off the left subclavian artery to bypass a third blocked artery. SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.8 Stem Cells Stem cells may be used to regenerate heart muscle that has been damaged by a heart attack Stem cells injected directly into the damaged heart muscle of mice and rats differentiated into new heart muscle cells and new blood vessels A “bioartificial” human heart has been grown by a research group by using cardiac muscle cells from a cadaver as a “scaffold” for human stem cells TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.8 Clearing Clogged Arteries Angioplasty involves inserting a catheter into a clogged artery. o When the catheter reaches the site of the clogged artery, a balloon is inflated to force the vessel open A stent is a metal mesh tube that inflates, expands, and locks the balloon into place. Figure 10.27 Angioplasty with stent o Some stents are coated with placement. a. A plastic tube (catheter) is inserted into the coronary artery until it medications that inhibit reaches the clogged area. b. A metal stent with a balloon inside it is pushed out the end inflammation and scar of the plastic tube into the clogged area. formation c. When the balloon is inflated, the vessel opens, and the stent is left in place to keep the vessel open. TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.8 Dissolving Blood Clots Thromboembolisms can be treated with tissue plasminogen activator (tPA) o Converts plasminogen to plasmin, an enzyme that dissolves blood clots Aspirin can be prescribed for individuals with symptoms of angina or stroke o Reduces stickiness of platelets and lowers the probability of clot formation TO PREVIOUS SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.8 Heart Transplants and Artificial Hearts Heart transplants The need for hearts to transplant is greater than the supply A left ventricular assist device (LVAD) can be implanted in the abdomen of patients waiting for an implant o A tube passes blood from the left ventricle to the LVAD, which pumps it into the aorta Figure 10.28 Human Heart. This human heart being cradled in the hands of a surgeon is about to be transplanted into a person whose own heart no longer TO PREVIOUS functions properly. SLIDE UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.8 Heart Transplants and Artificial Hearts Artificial hearts A total artificial heart (e.g., AbioCor) contains: o An internal battery o A controller (regulates pumping speed) o An external battery (powers the device by passing electricity through the skin) Figure 10.29 A total A pump moves silicon hydraulic fluid artificial heart. The AbioCor replacement between the left and right sacs to force heart is designed to be blood out of the heart and into the implanted within the chest cavity. pulmonary trunk and aorta TO PREVIOUS SLIDE