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UNIT B: Human Body Systems Chapter 8: Human Organization Chapter 9: Digestive System Chapter 10: Circulatory System and Lymphatic System: Section 10.2 Chapter 11: Respiratory System Chapter 12: Nervous System Chapter 13: Urinary System Chapter 14: Reproductive System UNIT B Chapter 10: Circulatory System and Lymphatic System Chapter 10: Circulatory System and Lymphatic System In this chapter, you will learn about the structure and function of the circulatory system and lymphatic system. In 2013, Lance Armstrong confessed to long-term blood doping and the use of banned substances. Blood doping involves artificially boosting the blood’s ability to bring more oxygen to muscles. Aerobic capacity and endurance improve where there are additional red blood cells available to carry oxygen. TO PREVIOUS SLIDE What is the composition of blood, including blood cells? What organs and structures control the flow of blood throughout the body? UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 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 (plasma proteins contribute to osmotic pressure of blood) • 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) TO PREVIOUS SLIDE 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 of leukocytes and platelets. The bottom layer contains the erythrocytes. UNIT B Chapter 10: Circulatory System and Lymphatic System Plasma Plasma contains a variety of inorganic and organic substances dissolved or suspended in water. TO PREVIOUS SLIDE Section 10.2 UNIT B Chapter 10: Circulatory System and Lymphatic System 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 Section 10.2 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 UNIT B Chapter 10: Circulatory System and Lymphatic System 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 Section 10.2 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 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 Section 10.2 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 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 antigenantibody complexes and allergens • Basophils: release histamine to promote blood flow to injured tissues TO PREVIOUS SLIDE Section 10.2 UNIT B Chapter 10: Circulatory System and Lymphatic System 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 Section 10.2 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 HIVinfected person has AIDS • A large number of abnormal white blood cells is a 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 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 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 Section 10.2 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 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 Section 10.2 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 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 UNIT B Chapter 10: Circulatory System and Lymphatic System Section 10.2 Check Your Progress 1. List the major components of blood, along with their functions. 2. Describe the cellular and molecular events that lead to blood clotting. 3. Identify some diseases that may be treatable with stem cell therapy. TO PREVIOUS SLIDE UNIT B TO PREVIOUS SLIDE Chapter 10: Circulatory System and Lymphatic System Section 10.2 UNIT B TO PREVIOUS SLIDE Chapter 10: Circulatory System and Lymphatic System Section 10.2