Chapter 8: BLOOD

8 BLOOD Chapter Outline Blood: Plasma, Blood Cells, and Platelets Plasma is the fluid part of blood Red blood cells carry oxygen and CO2 White blood cells defend and clean up Platelets help clot blood How Blood Transports Oxygen Hemoglobin is the oxygen carrier What determines how much oxygen hemoglobin can carry? Making New Red Blood Cells Different red blood cells Self markers on red blood cells include the ABO group of blood types Mixing incompatible blood types can cause the clumping called agglutination For safety’s sake, some people bank their own blood Rh Blood Typing Rh blood typing looks for an Rh marker There are also many other markers on red blood cells what can your blood say about you? Hemostasis and Blood Clotting Hemostasis prevents blood loss Factors in blood are one trigger for blood clotting Factors from damaged tissue also can cause a clot to form The formation of a blood clot is a first step in healing wounds Blood Disorders Anemias are red blood cell disorders Viruses and leukemias affect white blood cells Carbon monoxide poisoning prevents hemoglobin from binding oxygen Toxins can poison the blood Summary Review questions self-quiz critical thinking explore on your own Your future Objectives Learn the appearance, composition, and functions of all of the components of blood. Understand how blood transports oxygen. Know the factors involved in the production of red blood cells. Understand the importance of ABO and Rh blood typing. Learn the factors involved in hemostasis and blood clotting. Know the various blood disorders that can occur. Key Terms blood plasma erythrocytes (red blood cells) leukocytes (white blood cells) platelets hemoglobin oxyhemoglobin complete blood count (CBC) ABO blood typing agglutination Rh blood typing hemolytic disease of the newborn hemostasis thrombosis embolism stroke hemophilia anemias malaria thalassemia infectious mononucleosis leukemias chronic myelogenous leukemia septicemia toxemia Lecture Outline A. Transfusions replace the blood in individuals who have suffered major loss. 1. Blood used in transfusions must be carefully typed and screened for disease. 2. Efforts are underway to develop a synthetic blood. Blood: Plasma, Blood Cells, and Platelets A. Plasma is the fluid part of blood. 1. Plasma makes up about 55% of the blood volume. 2. Two-thirds of the plasma is water. 3. Other components of plasma include: plasma proteins (e.g., albumin), lipoproteins, ions, glucose, and dissolved gases. Red blood cells carry oxygen and CO2. 1. Approximately 45% of blood consists of erythrocytes (red blood cells). 2. The blood’s red color is due to the presence of hemoglobin. a. Hemoglobin is responsible for the transportation of oxygen. C. White blood cells defend and cleanup. 1. Some of the functions of leukocytes (white blood cells) are consuming dead cells, and targeting bacterial or viral agents in the body. 2. The number of white blood cells in the body depends on conditions in the body, such as the presence of an infection. 3. There are two main categories of leukocytes: granulocytes and agranulocytes. Granulocytes have visible granules in the cytoplasm. Neutrophils, eosinophils, and basophils are all classified as granulocytes. Neutrophils are the most common type of leukocytes. Agranulocytes have no granules present in the cytoplasm. Monocytes, a type of agranulocyte, eat up foreign substances in the body. Lymphocytes, the other type of agranulocyte, are involved in immune responses. 4. The lifespan of white blood cells can vary from hours to years. Platelets help clot blood. 1. Stem cells can become large megakaryocytes, which shatter into fragments called platelets. 2. Platelets are active in the formation of clots. How Blood Transports Oxygen A. Hemoglobin is the oxygen carrier. 1. A small amount of oxygen is dissolved directly in the plasma. 2. Most of the oxygen is transported as oxyhemoglobin, a combination of hemoglobin and oxygen. B. What determines how much oxygen hemoglobin can carry? 1. Oxygen attaches to hemoglobin when oxygen is plentiful and when the temperature is cool and the pH is neutral. This is similar to conditions in the lungs. Hemoglobin tends to release oxygen when the temperature is higher and the pH more acidic. a. The oxygen is given up to the tissues of the body. 3. Hemoglobin is made up of globulin and heme groups containing iron. a. The iron group, in the center of each heme group, is where the oxygen is attached. Making New Red Blood Cells A. The lifespan of a red blood cell is 120 days. 1. Old red blood cells are destroyed by macrophages via phagocytosis. 2. Then the amino acids are returned to the bloodstream and the iron goes to the bone marrow. 3. The remainder of the heme groups becomes a component of bile, which is produced by the liver. B. The bone marrow produces replacement red blood cells. 1. The normal erythrocyte count in males is 5.4 million, whereas it is 4.8 million in females. 2. When the blood count is low the kidneys release erythropoietin (EPO), which stimulates the bone marrow to produce more red blood cells. When the red blood cell count returns to normal, less EPO is produced as part of a negative feedback loop. ”Blood doping” can be accomplished by either removing red blood cells and then replacing them after the body has reestablished resting levels, or by injecting EPO to force the body to make more red blood cells. Different Red Blood Cells A. Antigens are chemical characteristics of a cell that encourage the immune system to initiate an immune response. 1. Antibodies can be produced to attack foreign antigens in the body. B. Self markers on red blood cells include the ABO group of blood types. 1. The markers for the ABO blood group are type A and type B. a. Type A has only A markers. b. Type B has only B markers. c. Type AB has both A and B markers. d. Type O has neither A nor B markers. C. Mixing incompatible blood types can cause the clumping called agglutination. 1. Type A individuals produce Anti-B antibodies. a. Anti-B antibodies will attack type B cells. 2. Type B individuals produce Anti-A antibodies. a. Anti-A antibodies will attack type A cells. 3. Type AB individuals produce neither Anti-A nor Anti-B. 4. Type O individuals produce both Anti-A and Anti-B. a. Type O is known as the universal donor and type AB is known as the universal recipient. D. All transfusions must be cross-matched to prevent an incompatibility. 1. If incompatible red blood cells are infused into a patient, antibodies will attack the foreign cells causing agglutination or clumping. 2. The transfusion of incompatible blood may result in blood clots forming in blood vessels and may possibly be fatal. E. For safety’s sake, some people bank their own blood. 1. In cases of elective surgery, individuals may donate blood for their own impending use. 2. This autologous transfusion eliminates the risk of typing errors or contracting a disease. Rh Blood Typing A. Rh blood typing looks for an Rh marker. 1. If an individual has the Rh marker, they are Rh+. 2. If an individual does not have the Rh marker, they are Rh-. 3. Hemolytic disease of the newborn can result from an Rh incompatibility. a. If an Rh- woman has an Rh+ baby, some of the baby’s red cells may cause the development of Anti-Rh antibody. b. Then if the next baby is also Rh+, some of the mother’s Anti-Rh antibodies will cross the placenta and attack the baby’s red blood cells. c. At this point the baby may require transfusions with blood that is free of the Anti-Rh antibodies. d. Hemolytic disease of the newborn can be prevented by giving the Rh- mom an injection of Anti-Rh gamma globulin (RhoGam) after each pregnancy with an Rh+ baby. B. There are also many other markers on red blood cells. 1. Cross-matching must be performed prior to all transfusions to insure that other antigen-antibody reactions do not occur. What Can Your Blood Say about You? A Blood tests can reveal elements of organ function, risk of heart disease, and presence of general infection. 1. As blood elements change constantly, repeated tests are necessary. B. Test conditions must be controlled. 1. Consumption of a host of foods or drugs may impact the drug profile. C. Normal ranges may vary by patient. 1. Age, weight, and gender are important in determining health and normal ranges of many blood factors. Hemostasis and Blood Clotting A. Hemostasis prevents blood loss. 1. When an injury occurs, the damaged blood vessel constricts. 2. Platelets clump together plugging the opening. 3. The blood coagulates and forms a clot. B. Factors in blood are one trigger for blood clotting. 1. An intrinsic mechanism from within the blood aids in clotting. a. First “factor X,” a plasma protein, is activated. b. Next, an enzyme called thrombin allows fibrinogen to form long fibrin filaments. The fibrin filaments form a net that catches platelets and blood cells, forming a clot. C. Factors from damaged tissue also can cause a clot to form. 1. An extrinsic mechanism from outside of the blood can aid in clotting. a. Damaged tissues can release chemicals that form thrombin in a similar manner as the intrinsic mechanism. b. Clot formation can be disadvantageous. i. A thrombus may form, dislodge, and travel as an embolus. ii. A blood clot may block blood flow to the brain and cause a stroke, which may cause paralysis on one side of the body. c. Individuals with hemophilia lack normal clotting factors. D. The formation of a blood clot is a first step in healing wounds. 1. In a wound, blood clotting begins immediately and leukocytes begin to cleanup wound debris. Blood Disorders A. Anemias are red blood cell disorders. 1. The term “anemia” indicates that erythrocytes are not transporting an adequate amount of oxygen to the tissues. Iron-deficient anemia results when an individual does not have enough iron to form sufficient amounts of hemoglobin. Pernicious anemia results from a deficiency of either folic acid or vitamin B12. Aplastic anemia occurs when the bone marrow is damaged by chemotherapy, radiation, or other medications. Hemolytic anemia results when the red blood cells are destroyed before their normal lifespan. Sickle cell disease can result in hemolytic anemia. Malaria occurs when a protozoan actually enters the red blood cells of the host organism. Thalassemia results from the production of abnormal hemoglobin that makes the red blood cells extremely fragile. B. Viruses and leukemias affect white blood cells. Infectious mononucleosis results from an infection of the Epstein-Barr virus. An overproduction of lymphocytes results and the patient feels tired with a low fever. Infection with the HIV virus causes the individual’s white blood count to drop, which leads to frequent infections. Leukemias result from cancer of the bone marrow, causing large amounts of abnormal white blood cells to be released into the circulation. a. Symptoms include: fever, frequent infections, anemia, internal bleeding, weight loss, and pain. C. Carbon monoxide poisoning prevents hemoglobin from binding oxygen. Hemoglobin is very highly attracted to carbon monoxide. Therefore, if there is a great deal of carbon monoxide in the air, the hemoglobin will attach to it and ignore its normal function of delivering oxygen to the tissues. Symptoms of carbon monoxide poisoning include light-headedness and headaches. D. Toxins can poison the blood. When bacteria release toxins into the bloodstream, it results in septicemia. MRSA (methicillin-resistant staph A) is an infection that is resistant to antibiotics. Toxemia involves the buildup of metabolic poisons in the bloodstream. a. Toxemia can result from damaged kidneys that are not effectively filtering the toxins from the bloodstream. Suggestions for Presenting the Material One of the strengths of the Starr/McMillan text is the inclusion of excellent summary tables such as the one found in Figure 8.1, which reviews the components of the blood. These tables should be called to the students’ attention, perhaps by using an overhead transparency or PowerPoint slide. Have a representative from the American Red Cross address the class regarding blood transfusions. They can review the donation process and the qualifications necessary to become a donor. The mechanism of clotting, and the somewhat confusing terms used to describe it, may need special attention and/or simplification. Blood typing is confusing to students. This is especially true because most believe that the ABO markers and the Rh markers are intimately connected since blood type is nearly always expressed that way, O- for example. Stress the independent nature of these two sets of markers. The study of forensics seems to interest nearly everyone. If possible, have a criminal justice or biotechnology instructor address the class regarding the latest techniques utilized in crime solving. With all of the crime shows on television today, one fun method of presenting blood and the concept of blood markers to students would be to show them excerpts from one or more shows and describe the investigative technique, along with how and why it works. Have the class discuss whether the forensic techniques involved are presented in a believable manner. Classroom and Laboratory Enrichment  Purchase a simulated blood typing kit. Several companies (Ward’s Scientific, Carolina Biologicals, Fisher Scientific) sell kits that use plastic coated particles instead of blood. Although there is no actual blood or blood products in the kit, they react very much like actual blood typing. You can enhance the kit by having the students say who could donate to which patient safely. Ask a representative of the American Red Cross to discuss the process of blood donation. Present a historical view of blood typing and blood transfusion. Discuss the safety of the blood supply with respect to HIV, both past and present. Compare what is tested for in blood in the United States versus testing procedures outside of the United States. Discuss implications for recipients of blood transfusions. Present the latest information on blood stem cells and distinguish these from stem cells that are obtained from embryos. Have a debate on the ethical considerations. Ask any member of the class who has traveled to places of high altitude to describe his/her breathing experiences. Classroom Discussion Ideas Is blood bank screening reliable and efficient? In the 1980s, a number of people contracted AIDS from contaminated blood transfusions. Why did this happen then? What would be the benefit of a synthetic “typeless” blood? How can a worker in a police crime lab detect if blood is present at the crime scene? How do they detect if the blood found is human? Why is hemophilia (inability of the blood to clot) more likely to be present in males than in females? Draw a pedigree chart showing the incidence of hemophilia in Queen Victoria’s lineage (use Figure 20.11 as a guide). How could this have been prevented? How is hemophilia treated today? Evaluate the truthfulness of the statement: “I’m a blood relative.” Is there a more accurate expression that could replace this one? Why is blood typing necessary before a transfusion is done? How does the patient possibly increase the difficulty of obtaining compatible blood if they have already received numerous transfusions? In what way is DNA matching more accurate in determining paternity than blood typing? What blood tests are currently performed on donor blood? Are these tests totally effective in preventing disease transmission via blood transfusion? Why or why not? Discuss blood clotting disorders other than classic hemophilia. What are the current treatments? Term Paper Topics, Library Activities, and Special Projects Research the regulations on blood doping for athletic events such as the Olympics. How are they able to detect this violation? The Rh factor is named for the Rhesus monkey. Trace the historical discovery of this protein marker in primates and humans. In addition, look into the discovery of RhoGam. How and when was it developed? How do the questions asked on the blood donation paperwork help insure the safety of the blood supply? Do you think these questions are effective? Can you think of additional questions or procedures that would better insure the safety of our blood transfusions? Look into the research for development of artificial blood. How effective are Oxygent and Oxycyte? Which functions of whole blood can be performed by artificial blood? Which functions cannot? Deaths of newborn babies from hemolytic disease of the newborn (Rh factor related) have been virtually eliminated since the 1950s. How has this been accomplished? Report on new treatments for blood disorders such as anemias and leukemias. Investigate the history of blood types and blood typing methods. Look into the ways that the human adapts to living at extremely high altitudes. Research the new “solid phase” blood typing techniques. How does this differ from past laboratory testing. Examine what some of the new methods of typing and genetic analysis of blood and tissues say about the notions of “race” and “ethnicity.” Why would a blood bank ask you about previous pregnancies? How might this affect your ability to be easily cross-matched? Videos, Animations, and Websites VIDEOS American Blood Centers – What Is Blood? Function and compostition of blood. http://www.youtube.com/watch?v=CRh_dAzXuoU United Blood Services – Human Blood Types Human blood type overview http://www.youtube.com/watch?v=wN--_z9eyJU United Blood Services – An Overview of Blood Donation An overview of the need for blood donations as well as the process. http://www.youtube.com/watch?v=0kdjmG7aIBE&feature=relmfu David Rogers - Vanderbilt University White blood cell chasing bacteria http://www.youtube.com/watch?v=JnlULOjUhSQ ANIMATIONS WISC – Online: Hematologic Cells Interactive animation and review of blood cells. http://www.wisc-online.com/objects/ViewObject.aspx?ID=CLT103 NobelPrize.org – The Blood Typing Game Role play an interactive animated game and work out blood typing for patients. http://www.nobelprize.org/educational/medicine/bloodtypinggame/ WEBSITES The National Heart, Lung, and Blood Institute Provides research, training, and education program to promote the prevention and treatment of heart, lung, and blood diseases http://www.nhlbi.nih.gov/index.htm The University of Nebraska at Omaha – Human Physiology and Anatomy Blood cell histology. http://www.unomaha.edu/hpa/blood.html Possible Responses to Review Questions Plasma is the liquid portion of the blood. It is made of primarily water and also plasma proteins, hormones, amino acids, lipoproteins, simple sugars, and dissolved gases. The function of plasma is to circulate these substances throughout the body and to participate in immunity and clot formation. The cellular components of blood are red blood cells, white blood cells, and platelets (which are actually cell fragments). They are all formed from stem cells in the bone marrow. The arrow on the top left of the diagram is pointing to the heme group and the bottom left points to the polypeptide chain. The most important factor that determines how much oxygen hemoglobin can carry is how much oxygen is present relative to the amount of carbon dioxide. Other factors that play a role in the amount of oxygen that hemoglobin can carry are temperature and pH. The agglutination response is when an antigen-antibody reaction occurs, which can result in the obstruction of small blood vessels or the destruction of the foreign red blood cells. This situation can be avoided by only transfusing blood of an appropriate type that has been found to be compatible by performing a cross-match. Hemostasis is the process by which a blood clot is formed. One method of clot formation involves intrinsic factors, which means that it originates from within the blood itself. Factor X, along with fibrinogen and platelets, are involved in this type of clot formation. Clots can also be formed via an extrinsic process (originates outside of the blood). In this method the damaged blood vessel or tissue releases chemicals that begin the clotting cascade. Possible Responses to Critical Thinking Questions Thrombocytopenia results in a low platelet count. Whenever platelets are below the normal values, there may be a lack of clot formation. As a result, you may be able to notice petechiae (small red spots on the skin), which indicate a reduced clotting capacity. (Note: The answer to this question may be derived from the actual meaning of the terms involved: thrombus = clot, thrombocyte = clotting cell, thrombocytopenia = lack of clotting cells.) The relationship between the amount of red blood cells and the release of erythropoietin is an example of a negative feedback mechanism. This type of response aids in maintaining a homeostatic balance in the bloodstream. Mosquitoes stop the clotting process through their salivary enzymes, ensuring they can feed longer. Possible Responses to Explore on Your Own Questions Students will discover some interesting facts about blood from the website givelife.org. Upon completion of this chapter in their textbook, their knowledge can be applied in some of the quiz questions on that site. The sections that are the most appropriate for your students are “Blood Trivia” and “What’s your blood IQ?” In addition, your students may develop an interest in donating blood or helping to organize a blood drive at your school. 98 Chapter Eight 97 Blood 98 Chapter Eight 97 Blood 98 Chapter Eight 97 Blood 98 Chapter Eight 97 Blood 98 Chapter Eight 97 Blood