PowerLecture: Chapter 8 Blood Learning Objectives Describe the composition and functions of blood. Explain how red blood cells transport oxygen. Explain the basis of blood typing. Define hemostasis and distinguish it from homeostasis. Learning Objectives (cont’d) Describe how blood disorders disrupt homeostasis and critical body functions, such as clotting. Impacts/Issues Chemical Questions Chemical Questions Healthy people have contaminants in their blood. The chemicals are products from everyday life: metals, secondhand cigarette smoke, pesticides, etc. Most of the chemicals did not even exist 50 years ago. Not enough is known about the long-term effects of these chemicals on human health, especially for the very young. Useful References for Impacts/Issues The latest references for topics covered in this section can be found at the book companion website. Log in to the book’s e-resources page at www.thomsonedu.com to access InfoTrac articles. Environmental Scorecard - In Your Community InfoTrac: Elevated Blood Lead Levels in Refugee Children – New Hampshire, 2003– 2004. Morbidity and Mortality Weekly Report, Jan. 21, 2005. How Would You Vote? To conduct an instant in-class survey using a classroom response system, access “JoinIn Clicker Content” from the PowerLecture main menu. Government regulation of substances such as lead seems to be effective. Should other suspect industrial chemicals be regulated? a. Yes, until companies are forced to prove their chemicals are harmless before selling them, they should be regulated. No, regulation hampers industry and is not necessary unless these chemicals are proven harmful. Useful References for How Would You Vote? The latest references for topics covered in this section can be found at the book companion website. Log in to the book’s e-resources page at www.thomsonedu.com to access InfoTrac articles. CDC: National Report on Human Exposure to Environmental Chemicals Environmental Working Group: Body Burden NRDC: Healthy Milk, Healthy Baby – Chemical Pollution and Mother’s Milk Section 1 Blood: Plasma, Blood Cells, and Platelets Blood: Plasma, Blood Cells, and Platelets Blood is a connective tissue; it contains plasma, blood cells, and cell fragments called platelets. Adult women of average size have 4-5 liters of blood in their bodies; men have slightly more. Figure 8.1 red blood cell white blood cell platelets Fig. 8.1, p.143 Blood: Plasma, Blood Cells, and Platelets Plasma is the fluid part of blood. Roughly 55% of whole blood is plasma, which is mostly water. Plasma proteins perform a variety of tasks: • • Albumin is important in maintaining osmotic balance and transports chemicals such as therapeutic drugs. Other plasma proteins include protein hormones, as well as proteins involved in immunity, blood clotting, and the transport of lipids and vitamins. Plasma further contains ions, glucose, amino acids, signaling molecules, and dissolved gases. Blood: Plasma, Blood Cells, and Platelets Red blood cells carry oxygen and CO2. Erythrocytes, or red blood cells, (45% of whole blood) are biconcave disks. • • They contain hemoglobin, an iron-containing protein that binds with oxygen. They also carry a small amount of carbon dioxide. Red blood cells originate from stem cells in the bone marrow. Animation: Cellular Components of Blood CLICK TO PLAY natural killer cells neutrophils eosinophils mast cells basophils T lymphocytes B lymphocytes forerunners of white blood cells (leukocytes) ? stem cells in marrow red blood cells (erythrocytes) monocytes (immature phagocytes) dendritic cells megakaryocytes macrophages platelets Fig. 8.2, p.145 Blood: Plasma, Blood Cells, and Platelets White blood cells perform defense and cleanup duties. Leukocytes, or white blood cells, make up a minor portion of whole blood and are responsible for housekeeping and defense; they also are derived from bone marrow. Leukocytes are of two main types: • • Granulocytes have stainable granules in the cytoplasm; they include neutrophils, eosinophils, and basophils; and they work in body defense activities. Agranulocytes have no visible granules; monocytes become macrophages; and lymphocytes become B cells, T cells, and natural killer cells. Blood: Plasma, Blood Cells, and Platelets Platelets help clot blood. Platelets are fragments of megakaryocytes produced by bone marrow stem cells. They are short lived, numerous, and function in blood clotting. Components Relative Amounts Functions Plasma portion (50%-60% of total volume): 1. Water 91%-92% of plasma volume 2. Plasma proteins (albumin, globulins, fibrinogen, etc.) 7%-8% 3. Ions, sugars, lipids, amino acids, hormones, vitamins, dissolved gasses Solvent Defense, clotting, lipid transport, roles in extracellular fluid volume, etc. 1%-2% Roles in extracellular fluid volume, pH, etc. Plasma portion (50%-60% of total volume): 1. White blood cells: Neutrophils Lymphocytes Monocytes(macrophages) Eosinophils Basophils 2. Platelets 3. Red blood cells 3,000-6,750 1,000-2,700 150-720 100-360 25-90 250,00-300,000 Phagocytosis during inflammation Immune responses Phagocytosis in all defense responses Defense against parasitic worms Secrete substances for inflammatory response and for fat removal from blood Roles in clotting 4,800,000-5,400,000 Oxygen, carbon dioxide transport per microliter Fig. 8.1, p.143 Video: Immortality Industry This video clip is available in CNN Today Videos for Anatomy and Physiology, 2004, Volume VIII. Instructors, contact your local sales representative to order this volume, while supplies last. Useful References for Section 1 The latest references for topics covered in this section can be found at the book companion website. Log in to the book’s e-resources page at www.thomsonedu.com to access InfoTrac articles. InfoTrac: FDA to Hear Artificial Blood Test Proposal. UPI NewsTrack, July 6, 2006. Section 2 How Blood Transports Oxygen How Blood Transports Oxygen Hemoglobin is the oxygen carrier. Only a tiny amount of oxygen is dissolved in blood plasma. Most of the oxygen is bound to the heme groups of hemoglobin; oxygen-bearing hemoglobin is called oxyhemoglobin. What determines how much oxygen hemoglobin can carry? How Blood Transports Oxygen The amount of oxygen bound to hemoglobin changes as conditions in the tissues vary. • • • Binding of oxygen is favored by conditions in the lungs: abundant oxygen, cooler temperature, and neutral pH. Release of oxygen is favored in the tissues where the oxygen levels are lower, temperatures higher, and pH more acidic. Hemoglobin also transports a small amount of carbon dioxide. LUNGS more O2 cooler less acidic Hb + O2 TISSUES HbO2 HbO2 Hb + O2 less O2 warmer more acidic p.146 Animation: Globin and Hemoglobin Structure CLICK TO PLAY How Blood Transports Oxygen Each hemoglobin molecule has four polypeptide chains (globin proteins), each of which possesses a heme group containing an iron molecule; each iron binds one molecule of oxygen. heme group coiled and twisted polypeptide chain of one globin molecule Fig. 8.3b, p.146 Useful References for Section 2 The latest references for topics covered in this section can be found at the book companion website. Log in to the book’s e-resources page at www.thomsonedu.com to access InfoTrac articles. Royal Society of Chemistry: Transport of Oxygen in the Blood InfoTrac: Hemoglobin Levels Are Testy Issue. New York Daily News, Feb. 12, 2006. Section 3 Hormonal Control of Red Blood Cell Production Hormonal Control of Red Blood Cell Production Red blood cells form from stem cells located in red bone marrow. The hormone erythropoietin from the kidneys is the stimulus for stem cell division. Mature red blood cells have no nuclei and live for only about 120 days. • • Macrophages remove old blood cells from the bloodstream; amino acids are returned to the blood, iron is returned to the bone marrow, and heme groups are converted to bilirubin. Red cell counts remain rather constant at 5.4 million/microliter for males and 4.8 million for females. Hormonal Control of Red Blood Cell Production A negative feedback loop stabilizes the red blood cell count. The kidneys monitor oxygen content of the blood; when it drops too low, the kidneys secrete erythropoietin. Erythropoietin stimulates bone marrow to produce more red blood cells; this increases the ability of the blood to carry oxygen. As oxygen levels rise, the information feeds back to the kidneys, which stop secreting erythropoietin. Kidney 2 Erythropoietin 1 3 Reduced oxygen in blood Developing red blood cells in red bone marrow Relieves 5 4 1 The kidneys detect reduced O2 in the blood. 2 When less O2 is delivered to the kidneys, they secrete the hormone erythropoietin into the blood. 3 Erythropoietin stimulates production of red blood cells in bone marrow. 4 The additional circulating RBCs increase O2 carried in blood. 5 The increased O2 relieves the initial stimulus that triggered erythropoietin secretion. Increased oxygen in blood RBCs Fig. 8.4, p.147 Section 4 Blood Types – Genetically Different Red Blood Cells Blood Types – Genetically Different Red Blood Cells All cells of the human body have surface proteins and other molecules that serve as “self” identification markers. Any protein marker that prompts a defensive action is called an antigen. The human body produces antibodies that recognize markers on foreign cells as “nonself” and stimulate immune reactions. Blood Types – Genetically Different Red Blood Cells The ABO group of blood types includes key self markers on red blood cells. ABO blood groups are based on glycoprotein surface markers on red blood cells. • • Type A has A markers; type B has B markers. Type AB has both markers; type O has neither marker. Depending on ABO blood type, the body will also possess antibodies to other blood types; ABO blood typing is done to prevent incompatible blood types from being mixed. Blood Types – Genetically Different Red Blood Cells Mixing incompatible blood types can cause the clumping called agglutination. Type A blood types do not have antibodies against A markers, but they do have antibodies to type B; Type B blood types do not have type B antibodies, but they do have type A antibodies, etc. • • A type A person cannot donate blood to a type B person because they are incompatible. When mixed, markers on the surface of red blood cells (not just the ABO markers) that do not match will cause the blood cells to undergo agglutination, a defense response where the blood cells clump. Animation: Genetics of ABO Blood Types CLICK TO PLAY Table 8.1, p.148 Table 8.2, p.151 Animation: Transfusions and Blood Types CLICK TO PLAY Blood Types – Genetically Different Red Blood Cells Clumped cells can clog small blood vessels, damage tissues, and cause death. compatible blood cells incompatible blood cells Fig. 8.5b, p. 149 Donor type B blood Recipient with type A blood Antigen B Antibody to type A blood Antigen A Antibody to type B blood Red blood cells from donor agglutinated by antibodies in recipient’s blood Red blood cells usually burst Clumping blocks blood flow in capillaries Side effects disrupt Oxygen and nutrient kidney function flow to cells and tissues is reduced Fig. 8.5a, p.149 Donor type B blood Recipient with type A blood Antigen B Antibody to type A blood Antigen A Antibody to type B blood Red blood cells from donor agglutinated by antibodies in recipient’s blood Red blood cells usually burst Side effects disrupt kidney function Clumping blocks blood flow in capillaries Oxygen and nutrient flow to cells and tissues is reduced Stepped Art Fig. 8.5a, p.149 Useful References for Section 4 The latest references for topics covered in this section can be found at the book companion website. Log in to the book’s e-resources page at www.thomsonedu.com to access InfoTrac articles. InfoTrac: Babies Accept Hearts with All Blood Types. UPI NewsTrack, April 5, 2005. Section 5 Rh Blood Typing Rh Blood Typing Rh blood typing looks for an Rh marker. Rh blood typing looks for the presence (Rh+) or absence (Rh-) of antigen on red blood cells. An Rh- person transfused with Rh+ blood will produce antibodies to the Rh marker. Rh Blood Typing An Rh- mother who bears an Rh+ child can also become sensitized to the Rh antigen; secondary children may be at risk from maternal antibodies. • • In hemolytic disease of the newborn, too many cells may be destroyed and the fetus dies. Medical treatment (RhoGam) given to the mother after the birth of the first Rh+ baby can inactivate the Rh antibodies. Animation: Rh Blood Type and Pregnancy Complications CLICK TO PLAY Rh Blood Typing There are also many other markers on red blood cells. Hundreds of different blood cell markers are known; most are widely scattered in the human population. To avoid problems with transfusions, blood undergoes cross-matching to exclude incompatible blood types from being used. Useful References for Section 5 The latest references for topics covered in this section can be found at the book companion website. Log in to the book’s e-resources page at www.thomsonedu.com to access InfoTrac articles. InfoTrac: Rh Disease: It’s Still a Threat. Contemporary OB/GYN, May 2004. Section 6 New Frontiers of Blood Typing New Frontiers of Blood Typing Blood + DNA: Investigating crimes and identifying mom or dad. Blood cell markers can be used to compare evidence from crime scenes to samples taken from possible perpetrators. Because blood groups are determined by genes, they are a useful source of information about a person’s genetic heritage. Blood typing can also be used to help determine the identity of a child’s father or mother. New Frontiers of Blood Typing For safety’s sake, some people bank their own blood. Even with screening, blood transfusions still carry the risk of being incompatible or potentially contaminated with infectious agents. In autologous transfusions, individuals predonate blood to themselves prior to surgeries in case transfusion is needed. Figure 8.7 New Frontiers of Blood Typing Blood substitutes must also avoid sparking an immune response. Blood substitutes have potential uses in situations where it is not feasible to perfectly match blood, such as in an ambulance or on the battlefield. To date, however, substitutes have been difficult to manufacture; OxygentTM is an oxygen carrier that has currently reached the final stages of clinical trials. Useful References for Section 6 The latest references for topics covered in this section can be found at the book companion website. Log in to the book’s e-resources page at www.thomsonedu.com to access InfoTrac articles. InfoTrac: Autologous Blood Transfusion: A Safer Way of Transfusion. GP, Feb. 24, 2006. Section 7 Hemostasis and Blood Clotting Hemostasis and Blood Clotting Hemostasis prevents blood loss. Hemostasis is the process that stops bleeding to prevent excess loss of blood. • • • Spasms of the smooth muscle in the damaged blood vessel stop blood flow for a few minutes by constriction of the vessel. Platelets clump to plug the rupture; they then release serotonin and other chemicals to prolong the spasm and attract more platelets. Finally, the blood coagulates to form the clot. Hemostasis can only seal tears and punctures that are relatively small. Animation: Hemostasis CLICK TO PLAY 1 Injury to blood vessel Blood flow 2 3 Wall of vessel contracts Platelets stick to collagen fibers of damaged vessel wall Blood flow decreases Blood flow Platelet decreases plug 4 More permanent clot forms Blood flow ceases Prothrombin Damaged cells and platelets release substances that activate clotting factors Prothrombin activator Ca2+ Fibrinogen Thrombin Ca2+ Fibrin threads (clot) Fig. 8.8, p.152 Hemostasis and Blood Clotting Factors in blood are one trigger for blood clotting. In the intrinsic clotting mechanism, internal damage activates a plasma protein (“factor X”) that triggers the formation of thrombin. Thrombin acts on fibrinogen to form insoluble threads of fibrin that will entrap blood cells and platelets to form a clot. Hemostasis and Blood Clotting Factors from damaged tissue also can cause a clot to form. In the extrinsic clotting mechanism, blood clotting is triggered by the release of substances outside the blood itself due to damage there; the pathway is similar to the intrinsic mechanism. Figure 8.8 Hemostasis and Blood Clotting Clots that form in unbroken vessels can be lifethreatening. • • A clot that stays where it forms is called a thrombus; one that breaks free and moves is called an embolus. A stroke occurs when an embolus blocks flow to some part of the brain. Hemophilia is a genetic disorder where clotting factors are absent from the blood so it does not clot properly. Damage to skin Epidermis Dermis Blood clot Blood vessels Neutrophils defensive WBCs) Fig. 8.9, p.153 Scab Regenerating epithelium Collagen fiber Blood vessel Collagen fiber Fig. 8.9, p.153 Useful References for Section 7 The latest references for topics covered in this section can be found at the book companion website. Log in to the book’s e-resources page at www.thomsonedu.com to access InfoTrac articles. American Academy of Family Physicians: Hypercoagulation InfoTrac: Factor V Leiden as a Common Genetic Risk Factor for Venous Thromboembolism. Journal of Nursing Scholarship, Spring 2006. Section 8 Blood Disorders Blood Disorders Anemias are red blood cell disorders. Anemias develop when red blood cells deliver too little oxygen to the tissues. Two types result from nutrient deficiencies: • • In iron-deficiency anemia, red cells contain too little hemoglobin, usually resulting from an iron-poor diet. Pernicious anemia is caused by a deficiency of folic acid or vitamin B12. Aplastic anemia results from a destruction of the red bone marrow and its stem cells. Blood Disorders Hemolytic anemias are caused by the premature destruction of red blood cells. • • • Sickle cell anemia, a genetic disease, is one cause. Malaria is a major cause of hemolytic anemia and follows infection by a protozoan transmitted by mosquitoes. In thalassemia, individuals produce abnormal hemoglobin. Figure 8.10 Fig. 8.10, p.154 Fig. 8.10, p.154 Blood Disorders Carbon monoxide poisoning prevents hemoglobin from binding oxygen. Carbon monoxide (CO) is a colorless, odorless gas present in auto exhaust fumes and smoke from wood, coal, charcoal, and tobacco. CO binds to hemoglobin 200 times more tightly than oxygen, thus blocking oxygen transport to tissues. Blood Disorders Mononucleosis and leukemias affect white blood cells. Infectious mononucleosis is caused by the Epstein-Barr virus, which triggers overproduction of lymphocytes. Leukemias are very serious cancers in which there is an overproduction of white blood cells and destruction of bone marrow; chronic myelogenous leukemia is one type. Fig. 8.11, p.154 Blood Disorders Other viral infections, such as HIV (the human immunodeficiency virus), can also harm or destroy white blood cells. Toxins can destroy blood cells or poison the blood in other ways. Septicemia can occur when bacteria release toxins into the blood; Staphylococcus aureus (Staph A) is one important example. Toxemia happens when metabolic poisons accumulate in the body; toxemia can occur if the kidneys do not adequately filter the blood and remove these poisons. Video: Global AIDS This video clip is available in CNN Today Videos for Biology, 2003, Volume VII. Instructors, contact your local sales representative to order this volume, while supplies last. Useful References for Section 8 The latest references for topics covered in this section can be found at the book companion website. Log in to the book’s e-resources page at www.thomsonedu.com to access InfoTrac articles. Leukemia & Lymphoma Society National Heart, Lung, and Blood Institute: Blood Diseases and Resources Information InfoTrac: When Mono Strikes. Nina M. Riccio. Current Health 2, March 2000. InfoTrac: Anemia: That Run-Down Feeling. Shiela Globus. Current Health 2, Mar. 1999.