Chapter 18 Blood - Biology PDF

***[CHAP 18]*** 1. **Explain and discuss each individual function of blood and its importance in homeostasis and human life.** - **Transport**: - Blood transports oxygen and carbon dioxide to the lungs, nutrients to the GI tract, hormones from endocrine glands, and heat and wastes...

***[CHAP 18]*** 1. **Explain and discuss each individual function of blood and its importance in homeostasis and human life.** - **Transport**: - Blood transports oxygen and carbon dioxide to the lungs, nutrients to the GI tract, hormones from endocrine glands, and heat and wastes from systemic cells. - **Regulation**: - **Body Temperature**: Blood absorbs heat from cells and releases it through surface blood vessels. - **pH**: Blood regulates pH by absorbing acids and bases from cells and using chemical buffers. - **Fluid Balance**: Blood regulates fluid balance by accepting water from the GI tract and eliminating it through numerous functions. - **Protection**: - **Defense**: Blood contains leukocytes, plasma proteins, and other molecules that help protect the body against harmful substances. - **Blood Loss Prevention**: Blood has platelets and plasma proteins that protect the body against blood loss. 2. **Explain that blood is composed of formed elements and plasma, which is the liquid component of blood; some formed elements are complete cells such as the white blood cells, while red blood cells are anucleated, and platelets are broken off pieces of cells.** **Formed Elements** - **Red Blood Cells (Erythrocytes)**: Anucleated cells that transport respiratory gases. - **White Blood Cells (Leukocytes)**: Complete cells that defend against pathogens. - **Platelets**: Broken-off pieces of cells involved in blood clotting. **Plasma** - The liquid component of blood contains proteins and dissolved solutes. 3. **Explain and discuss the physical characteristics of whole blood.** **Color**: - Blood color depends on its oxygen content. Oxygen-rich blood appears bright red or scarlet. Oxygen-poor blood appears dark red and somewhat bluish. **Viscosity**: - Blood is four to five times thicker than water. This thickness depends on the amount of dissolved substances in the blood. **Volume**: - Blood volume is typically around 5 liters but can range from 4 to 5 liters. This volume is essential for maintaining blood pressure. **Temperature**: - Blood temperature is approximately 1°C higher than body temperature. This higher temperature helps warm the areas through which the blood travels. **pH**: - Blood pH ranges between 7.35 and 7.45. This range is crucial for preventing the denaturing of proteins and maintaining proper physiological function. 4. **Show and explain how blood is separated into its main components, formed elements (packed RBCs and Buffy coat (WBCs and platelets)) and plasma, using a centrifuge** - **Centrifugation:** Spins blood to separate it into three layers. - **Bottom Layer:** Erythrocytes (44% of the blood). - **Middle Layer:** Buffy coat (less than 1%), consisting of leukocytes and platelets. - **Top Layer:** Plasma (55% of the blood). - **Process:** - Whole blood is spun in a centrifuge. - Heavier elements (erythrocytes) settle at the bottom. - Buffy coat forms between erythrocytes and plasma. - Plasma remains on top. 5. **Explain that the % packed RBC is termed the hematocrit.** **Hematocrit**: Percentage of volume occupied by red blood cells. Clinical hematocrit refers to the percentage of erythrocytes alone **Components of Blood (pp. 702--703); Figure 18.1 (p. 703)** **The true blood hematocrit refers to the percentage of volume of all formed elements (erythrocytes, leukocytes, and platelets) in the blood.** **a. A clinical hematocrit is only the percentage of erythrocytes.** **b. Hematocrit values vary and are dependent upon the age and sex of the individual.** **c. An elevated hematocrit may indicate dehydration, living at a high altitude, or possible blood doping; a low hematocrit suggests possible anemia.** 6. **Explain and discuss the components of plasma.** Plasma consists of: - **Water** (92%). - **Proteins** (7%): Albumins, globulins, fibrinogen. - **Dissolved solutes** (1%) **Composition of Blood Plasma: Plasma is composed mainly of water (92%), plasma proteins (7%), and dissolved organic and inorganic molecules and ions (1%). (pp. 704--706)** **A. Plasma Proteins (pp. 704--705); Table 18.2 (p. 705)** **Blood, a colloid, consists of the plasma proteins albumin, globulin, fibrinogen; regulatory proteins such as enzymes, hormones; and plasma.** **Most of these proteins are produced in the liver.** 7. **Identify the common electrolytes found in plasma; discuss the basic functions of each.** - **Electrolytes**: - **Cations**: Sodium, potassium, calcium. - **Anions**: Chloride, bicarbonate, phosphate. - **Functions**: Maintain osmotic balance, membrane potentials, and pH **Other Solutes (p. 706)** **Other solutes of the blood consist of electrolytes---cations: sodium, potassium, calcium, and hydrogen; and anions: chloride, bicarbonate, and phosphate. (Table 18.3 p. 706)** **Functions: Electrolytes help maintain membrane potentials, pH balance, and regulate the osmotic balance of the blood.** 8. **Identify the common nutrients found in plasma.** Glucose, amino acids, lipids **Other Solutes (p. 706)** **Nutrient molecules are also contained in the blood. (Table 18.4 p. 706)** **These include glucose, amino acids, lipids (including cholesterol, triglycerides, and phospholipids).** 9. **What is the main component of plasma?** **Water**: 92% of plasma **Composition of Blood Plasma: Plasma is composed mainly of water (92%), plasma proteins (7%), and dissolved organic and inorganic molecules and ions (1%). (pp. 704--706)** **Water is the main component of plasma, accounting for about 92% of its composition.** 10. **List and describe the four types of plasma proteins and describe their basic functions.** - **Albumin**: Osmotic force, viscosity, transports lipids. - **Globulins**: Transport, antibodies. - **Fibrinogen**: Coagulation, forms fibrin. - **Regulatory proteins**: Enzymes, hormones **. Plasma Proteins (pp. 704--705); Table 18.2 (p. 705)** **Albumin is the most abundant plasma protein. It exerts osmotic force, contributes to blood viscosity, and transports some ions, hormones, and lipids.** **Globulins function for transport and serve as antibodies that immobilize pathogens.** **Fibrinogen participates in blood coagulation (clotting) by converting into long, insoluble strands of fibrin.** **Regulatory proteins, the least abundant plasma proteins, consist of enzymes that accelerate chemical reactions and hormones that are transported to target cells.** 11. **Where are most of these proteins produced?** **Liver** **Plasma Proteins (pp. 704--705); Table 18.2 (p. 705)** **Most of these proteins are produced in the liver.** 12. **What is colloid osmotic pressure and what is its main contributor?** **Colloid osmotic pressure**: Prevents fluid loss from blood, mainly caused by **albumin** **Plasma Proteins (pp. 704--705); Table 18.2 (p. 705)** **Colloid osmotic pressure (COP) is the osmotic pressure exerted by plasma proteins that draws fluid into the blood, thus preventing excess fluid loss between capillaries and interstitial fluid. Albumin is the main contributor to colloid osmotic pressure.** 13. **List the three types of formed elements in the blood and describe their basic functions.** - **Erythrocytes**: Transport oxygen and carbon dioxide. - **Leukocytes**: Defend against pathogens. - **Platelets**: Aid in blood clotting **Functions and General Composition of Blood: Blood is a specialized fluid that is transported through the cardiovascular system. (pp. 701--704)** **Erythrocytes (red blood cells) transport respiratory gases.** **Leukocytes (white blood cells) defend against pathogens.** **Platelets aid in blood clotting.** 14. **Define hematopoiesis Where does it occur?** **Hematopoiesis**: Formation of blood cells. Occurs in **red bone marrow** **Formed Elements in the Blood: Approximately 45% of whole blood is comprised of the formed elements, which are the red blood cells, white blood cells, and platelets. (pp. 707--722); Table 18.5 (p. 707)** **A. Hematopoiesis (pp. 707--710)** **Hematopoiesis begins in the embryonic period of development when the yolk sac forms blood stem cells and primitive formed elements.** **By the fifth week of development, the liver becomes the primary site for hematopoiesis and continues this process until the fifth month of development.** **At this point, hematopoiesis begins in the red bone marrow (myeloid tissue) and remains the major site of hematopoiesis once the child is born. In adults, hematopoiesis continues in the flat bones of the axial skeleton and head of the femur and humerus** 15. **Define the term stem cell and discuss the blood stem cells; explain the differences between types of stem cells and what cells they will form.** - **Stem cells**: Undifferentiated cells that can develop into different types of blood cells. - **Hemocytoblasts**: Blood stem cells differentiate into: - **Myeloid stem cells**: Form erythrocytes, platelets, and all leukocytes except lymphocytes. - **Lymphoid stem cells**: Form lymphocytes **The process of hematopoiesis starts with hemocytoblasts, or hemopoietic stem cells. (Figure 18.3 p. 708)** **a. Hemocytoblasts are multipotent cells since they can differentiate and develop into many types of cells.** **b. The process begins with the development of two different lines of cells: the myeloid line produces erythrocytes, all leukocytes except lymphocytes, and megakaryocytes; the lymphoid line forms only lymphocytes.** 16. **Differentiate between erythropoiesis, leukopoiesis, and thrombopoiesis.** - **Erythropoiesis**: The process of erythrocyte production. It begins with a myeloid stem cell and forms a proerythroblast, eventually becoming a reticulocyte in a process taking about 5 days. A mature erythrocyte forms after 1--2 days in circulation - **Leukopoiesis**: The process of leukocyte production. It involves the maturation of granulocytes, monocytes, and lymphocytes - **Thrombopoiesis**: The process of platelet production. Megakaryocytes form platelets by producing long extensions called proplatelets, which are sliced off as fragments that enter the circulation **Erythropoiesis begins with the stimulation of a myeloid stem cell forming a proerythroblast, then eventually a reticulocyte in a process that takes about 5 days; a mature erythrocyte forms after a day or two in circulation containing hemoglobin but not a nucleus or organelles.** **Leukocyte production, called leukopoiesis, involves granulocyte, monocyte, and lymphocyte maturation.** **Platelets, or megakaryocytes, form platelets by forming long extensions called proplatelets that eventually are sliced off as fragments that enter circulation.** 17. **Differentiate between hemocytoblast, myeloid stem cells, lymphoid stem cells, proerythroblasts, reticulocytes, and megakaryocytes** - **Hemocytoblasts**: Multipotent stem cells that can differentiate into various blood cells - **Myeloid stem cells**: Form erythrocytes, all leukocytes except lymphocytes, and megakaryocytes - **Lymphoid stem cells**: Form lymphocytes only - **Proerythroblasts**: The first cell in erythropoiesis that forms from myeloid stem cells - **Reticulocytes**: Immature erythrocytes released into circulation after 5 days of erythropoiesis - **Megakaryocytes**: Large cells in the red bone marrow that form platelets **The process of hematopoiesis starts with hemocytoblasts, or hemopoietic stem cells. (Figure 18.3 p. 708)** **a. Hemocytoblasts are multipotent cells since they can differentiate and develop into many types of cells.** **b. The process begins with the development of two different lines of cells: the myeloid line produces erythrocytes, all leukocytes except lymphocytes, and megakaryocytes; the lymphoid line forms only lymphocytes.** **Erythropoiesis begins with the stimulation of a myeloid stem cell forming a proerythroblast, then eventually a reticulocyte in a process that takes about 5 days. Platelets, or megakaryocytes, form platelets by forming long extensions called proplatelets that eventually are sliced off as fragments that enter circulation.** 18. **Explain and discuss the red blood cells, termed the erythrocytes.** **Erythrocytes (red blood cells)**: Anucleate, biconcave-shaped cells that transport oxygen and carbon dioxide between tissues and lungs. They contain hemoglobin, which binds to oxygen and carbon dioxide for transport **Erythrocytes (pp. 710--718)** **Erythrocytes, or red blood cells, are anucleate formed elements that transport oxygen and carbon dioxide between tissues and the lungs due to their biconcave structure that allows efficient movement through the bloodstream. (Figure 18.5 p. 710)** **A red-pigmented protein consisting of four protein building blocks that transport oxygen is called hemoglobin.** 19. **Describe the structure of a red blood cell.** **Structure**: Erythrocytes are biconcave discs that lack a nucleus and organelles, making them highly efficient for gas transport **Erythrocytes (pp. 710--718)** **Erythrocytes, or red blood cells, are anucleate formed elements that transport oxygen and carbon dioxide between tissues and the lungs due to their biconcave structure that allows efficient movement through the bloodstream. (Figure 18.5 p. 710)** **They lack a nucleus and organelles, making them highly efficient for gas transport** 20. **Describe the overall structure of hemoglobin, along with its function; discuss the independent structure of heme and the independent structure of globin, along with their individual functions.** **Hemoglobin**: A red-pigmented protein made of four protein building blocks. Each molecule has four heme groups that allow for the binding of oxygen to iron in the heme group - **Heme**: Binds oxygen to its iron molecule for transport in the blood - **Globin**: Forms a weak bond with carbon dioxide for transport in the blood **. Erythrocytes (pp. 710--718)** **A red-pigmented protein consisting of four protein building blocks that transport oxygen is called hemoglobin.** **a. Each globulin chain contains a heme group, which allows for the binding of oxygen to the iron in the heme group and thus transport in the blood. (Figure 18.6 p. 710)** **b. Because each molecule of hemoglobin has four heme groups, it can bind to four oxygen molecules through a weak bond that allows rapid attachment and detachment of the oxygen.** **c. Carbon dioxide forms a weak bond with the globin protein molecule as it moves through the bloodstream.** 21. **How long do red blood cells live?** **Lifespan**: About 120 days **Erythrocyte Destruction (Figure 18.8 p. 713)** **a. Erythrocytes lack a nucleus and organelles, yielding them unable to synthesize proteins necessary for repair and making them more vulnerable to wear and tear during circulation.** **b. Erythrocytes live about 120 days, but all their components are recycled or excreted from the body.** 22. **Explain the role of erythropoietin (EPO) in red blood cell production; what factors regulate the release of EPO? What organ produces EPO?** **EPO (Erythropoietin)**: Hormone produced primarily by the **kidneys**, stimulating erythrocyte production. Release is triggered by low blood oxygen levels. The process is controlled by negative feedback **The kidneys are the primary producers of erythropoietin hormone, the stimulator for erythrocyte production. (Figure 18.7 p. 712)** **a. Erythropoietin release is stimulated by an oxygen level decrease in the blood detected by the kidneys, causing the red bone marrow to increase erythrocyte production, resulting in an increase of oxygenated erythrocytes and an increase in blood oxygen levels.** **b. The process is controlled through negative feedback based on blood oxygen levels.** **c. Environmental factors also can affect EPO release, such as visiting or living in a higher altitude; since less oxygen is present, EPO is released and erythropoiesis increases.** 23. **Explain red blood cell destruction along with the recycling of certain red blood cell components.** **Destruction**: Erythrocytes are phagocytized by macrophages in the liver and spleen. Hemoglobin is broken down, and its components are recycled: - **Globin**: Broken down into amino acids. - **Heme**: Converted into biliverdin and bilirubin, then excreted. - **Iron**: Stored in the liver **Erythrocyte Destruction (Figure 18.8 p. 713)** **a. Erythrocytes lack a nucleus and organelles, yielding them unable to synthesize proteins necessary for repair and making them more vulnerable to wear and tear during circulation.** **b. Erythrocytes live about 120 days, but all their components are recycled or excreted from the body.** **c. Macrophages of the spleen and liver phagocytize old erythrocytes.** **d. Hemoglobin is removed from the erythrocyte with the heme group still attached to the globin; the globin is broken down into free amino acids to be reused by the body.** **e. Heme groups (without the Fe2+) are first converted within macrophages to green biliverdin, then to bilirubin, a yellow component of digestive secretion called bile, then to urobilinogen in the small intestine, where it will either be converted to stercobilin, a brown pigment of the feces, or converted to urobilin, a yellow pigment, an excretion of the kidneys.** **f. Iron components of hemoglobin are transported to and stored in the liver.** 24. **Define polycythemia. Discuss blood doping and certain red blood cell disorders.** - **Polycythemia**: An increased number of erythrocytes, leading to thicker blood - **Blood Doping**: The illegal procedure of increasing red blood cell count to enhance oxygen delivery to muscles, either by re-injecting one\'s own blood or using EPO. Complications include increased blood viscosity, leading to cardiovascular damage. **Clinical View 18.1: Blood Doping (p. 711)** **Blood doping is an illegal procedure used by some athletes that results in an increased red blood cell volume and, therefore, the amount of oxygen that can be delivered to the muscles.** **There are several medical complications associated with blood doping, such as increased blood viscosity, which causes the heart to work harder to pump the thicker blood; permanent cardiovascular damage can occur, even leading to death.** **Clinical View 18.2: Anemia (p. 714)** **Anemia is any condition in which either the percentage of red blood cells is lower than normal or there is a decreased oxygen-carrying capability of the blood due to hemoglobin abnormalities.** **Sickle-cell disease is an autosomal recessive anemia that occurs when a person inherits two copies of the sickle-cell gene; erythrocytes are sickle-shaped at lower blood oxygen levels and can get stuck in smaller blood vessels.** - **Erythrocyte Disorders**: Various forms of anemia (e.g., sickle-cell, iron deficiency, pernicious anemia) 25. **Describe the different types of anemia.** **Anemia**: A condition where red blood cells or hemoglobin levels are too low to carry sufficient oxygen. Types include: - **Aplastic anemia**: Defective red bone marrow. - **Congenital hemolytic anemia**: Fragile red blood cells. - **Erythroblastic anemia**: Genetic mutation affecting hemoglobin production. - **Hemorrhagic anemia**: Blood loss. - **Pernicious anemia**: Inability to absorb vitamin B12. - **Sickle-cell anemia**: Inherited disorder causing sickle-shaped erythrocytes. - **Iron-deficiency anemia**: Low iron levels **Aplastic anemia---significant decrease in formation of both erythrocytes and hemoglobin due to defective red bone marrow.** **Congenital hemolytic anemia occurs when the destruction of erythrocytes is faster than normal due to a genetic defect that makes the erythrocyte plasma membrane very fragile.** **Erythroblastic anemia or beta-thalassemia is an inherited disease in which a genetic mutation affects hemoglobin production, allowing large numbers of immature erythroblasts to enter circulation.** **Hemorrhagic anemia is due to heavy blood loss.** **Pernicious anemia is caused by the failure of the body to absorb vitamin B12 due to lack of intrinsic factor from the stomach.** **Sickle-cell disease is an autosomal recessive anemia that occurs when a person inherits two copies of the sickle-cell gene; erythrocytes are sickle-shaped at lower blood oxygen levels and can get stuck in smaller blood vessels.** **Iron deficiency anemia---low amounts of iron that mean fewer red blood cells with lower oxygen-carrying capability.** 26. **Discuss blood typing; discuss the ABO blood types system and the Rh blood types.** **ABO Blood Types**: - **A**: A antigen, anti-B antibodies. - **B**: B antigen, anti-A antibodies. - **AB**: Both A and B antigens, no antibodies. - **O**: No antigens, both anti-A and anti-B antibodies **Rh Blood Types**: - **Rh-positive**: Presence of Rh antigen (antigen D). - **Rh-negative**: Absence of Rh antigen **Blood Types (p. 714--716)** **a. Surface antigens or agglutinogens are molecules located on the plasma membrane of erythrocytes.** **b. The best-known antigens are those of the ABO blood group.** **c. The presence or absence of A antigen and B antigen determines your ABO blood type. (Figure 18.9a p. 715)** **Type A blood has the A antigen.** **Type B blood has the B antigen.** **Type AB blood has both A and B antigens.** **Type O has neither antigen.** **e. Rh Factor is another common surface antigen on the erythrocyte plasma membrane.** **The Rh blood type is determined by the presence or absence of the Rh antigen D.** **If antigen D is present, the individual is Rh positive, and if absent, the person is Rh negative.** 27. **Explain and discuss the importance of blood typing in the performance of blood transfusions.** Incompatible blood types result in **agglutination**, where antibodies bind to surface antigens, causing clumping and hemolysis. This can block blood vessels and damage organs **Clinical Considerations About Blood Type (pp. 716--717)** **a. Combining incompatible blood types causes antibodies of one type to bind to surface antigens of a second type, resulting in the clumping of erythrocytes called agglutination, which causes blood vessel blockage and inadequate circulation. (Figure 18.10 p. 717)** **b. Hemolysis is the process of erythrocyte rupture due to clumping and can cause alternate hemolytic reactions and organ damage.** **c. Because of agglutination and subsequent hemolysis, only certain blood types are compatible** 28. **Identify which blood types are the universal donor and the universal recipient.** - **Universal Donor**: **O-negative** blood. - **Universal Recipient**: **AB-positive** blood Type O- blood is considered the Universal Donor because it can be given to any other blood type; Type AB+ is the Universal Recipient because they can receive any other blood type 29. **Define antigen, antibodies, and agglutination.** - **Antigen**: Molecules on the surface of erythrocytes. - **Antibodies**: Y-shaped proteins that target antigens perceived as foreign. - **Agglutination**: Clumping of erythrocytes due to incompatible blood types **Blood Types (p. 714--716)** **a. Surface antigens or agglutinogens are molecules located on the plasma membrane of erythrocytes.** **d. The ABO surface antigens are accompanied by specific antibodies in the blood plasma; antibodies or agglutinins are Y-shaped proteins of the plasma that recognize and immobilize antigens of erythrocytes they perceive as foreign.** **The ABO blood group contains both anti-A and anti-B antibodies** 30. **Explain and discuss Rh incompatibility in pregnancy.** **Rh Incompatibility**: Occurs when an Rh-negative mother is exposed to Rh-positive fetal blood during childbirth, leading to the formation of anti-D antibodies. This can cause **hemolytic disease of the newborn** in subsequent pregnancies. The condition can be prevented by administering **RhoGAM** **During pregnancy, if a mother's blood type is Rh negative and if her fetus's blood type is Rh positive, there can possibly be a medical complication generally in a second pregnancy.** **The mother can be exposed to the Rh antigen during birth and then produce antibodies against Rh.** **During the next pregnancy, if the fetus is again Rh positive, the Rh-antibodies can cross the placenta resulting in hemolytic disease of the newborn or erythroblastosis fetalis.** **The newborn presents with anemia and hyperbilirubinemia and may develop heart failure and must be given a transfusion.** 31. **Explain and discuss the white blood cells, termed the leukocytes.** **Leukocytes (white blood cells)**: Motile, flexible cells with a nucleus and organelles. They lack hemoglobin and help defend the body against pathogens. Leukocytes can exit blood vessels and enter tissues to perform their functions **Leukocytes are motile, flexible "true" cells found in tissues; they contain a nucleus and organelles but lack hemoglobin and serve to help defend the body against pathogens.** 32. **Discuss the two major groupings of white blood cells, which are the granulocytes and agranulocytes; explain the basis of the names for the two groups.** - **Granulocytes**: Contain visible granules in their cytosol when stained (e.g., neutrophils, eosinophils, basophils) - **Agranulocytes**: Lack visible granules in their cytosol under light microscopy (e.g., lymphocytes, monocytes) The two groups of leukocytes are granulocytes and agranulocytes based on the presence or absence of secretory vesicles in the cytosol when stained and viewed with a light microscope 33. **Name the five types of leukocytes and list them in order of relative abundance.** - **Neutrophils** - **Lymphocytes** - **Monocytes** - **Eosinophils** - **Basophils** **Granulocytes** **a. Neutrophils are the most abundant leukocytes. b. Eosinophils c. Basophils 6. Agranulocytes a. Monocytes b. Lymphocytes** 34. **Explain that though white blood cells are termed blood cells, most of their work is performed extravascularly in the tissues; they escape the blood vessels in capillaries and postcapillary venules by a process termed diapedesis.** **Diapedesis**: The process by which leukocytes exit blood vessels by squeezing between endothelial cells and enter tissues, where most of their work occurs Diapedesis is the process of leukocytes entering tissues by the act of squeezing between endothelial cells of blood vessel walls 35. **Explain and discuss the process of diapedesis. Define the term chemotaxis.** - **Diapedesis**: Leukocytes exit blood vessels by squeezing through endothelial cells to enter tissues - **Chemotaxis**: The process where leukocytes are attracted to infection sites by chemicals released from damaged or infected cells **Diapedesis is the process of leukocytes entering tissues by the act of squeezing between endothelial cells of blood vessel walls.** **Chemotaxis is the process by which leukocytes are attracted to sites of infection due to the release of molecules by damaged cells, dead cells, or pathogens.** 36. **Discuss the cellular appearance and role of each of five types of white blood cells: neutrophils, eosinophils, basophils, lymphocytes, and monocytes.** - **Neutrophils**: Most abundant, multilobed nucleus; involved in bacterial infections - **Eosinophils**: Bilobed nucleus; attack parasitic worms and involved in allergic reactions - **Basophils**: Least numerous, bilobed nucleus; release histamine (inflammation) and heparin (anticoagulant) - **Lymphocytes**: Large nucleus, thin rim of cytosol; involved in immune responses (T-cells, B-cells, NK cells) - **Monocytes**: Largest, kidney-shaped nucleus; transform into macrophages and phagocytize pathogens **Granulocytes** **a. Neutrophils are the most abundant leukocytes. Increased neutrophils may indicate an acute bacterial infection.** **b. Eosinophils---if the body is attacked by parasitic worms, eosinophils release chemical mediators that attack the worms.** **c. Basophils are the least numerous of the granulocytes. Basophils release histamine, a capillary vasodilator, and heparin, an anticoagulant, which are released during inflammation and allergic reactions.** **Agranulocytes** **a. Monocytes---after about 3 days in circulation, monocytes exit the bloodstream and take up residence within tissues where they transform into large phagocytic cells called macrophages and phagocytize bacteria, cellular fragments, and debris.** **b. Lymphocytes reside in lymphatic organs and structures and are about the size of an erythrocyte.** **There are three categories of lymphocytes: T-lymphocytes (T-cells) manage and direct an immune response by directly attacking foreign cells and virus-infected cells; B-lymphocytes (B-cells) become plasma cells and produce antibodies; and NK (Natural Killer) cells that attack abnormal and infected cells.** **Granulocytes** **a.** **Neutrophils are the most abundant leukocytes** **Increased neutrophils may indicate an acute bacterial infection.** **b.** **Eosinophils** **If the body is attached by parasitic worms, eosinophils release chemical mediators that attach the worms.** **c.** **Basophils are the least numerous of the granulocytes** **Basophils release histamine, a capillary vasodilator, and heparin, an anticoagulant which are released during inflammation and allergic reactions.** **Agranulocytes have such small granules that they are not visible using light microscopy.** **a.** **Monocytes can be up to three times the diameter of an erythrocyte** **After about 3 days in circulation, monocytes exit the blood stream and take up residence within tissues, where they transform into large, phagocytic cells called macrophages and phagocytize bacteria, cellular fragments, and debris.** **b.** **Lymphocytes reside in lymphatic organs and structures and are about the size of an erythrocyte** **There are three categories of lymphocytes: T-lymphocytes (T-cells) that manage and direct an immune response by directly attacking foreign cells and virus-infected cells; B-lymphocytes (B-cells) that become plasma cells and produce antibodies; and NK (Natural Killer) cells that attack abnormal and infected cells.** 37. **Explain and discuss that the differential count of white blood cells changes under certain conditions; define the terms leukocytosis and leukopenia. How would determining the number and type of WBCs present help determine a disease or condition?** - **Leukocytosis**: Elevated white blood cell count, often due to infection, stress, or inflammation - **Leukopenia**: Reduced white blood cell count, which increases the risk of infection - **Differential Count**: Helps identify infections, cancers, or immune disorders by assessing the relative percentages of different types of leukocytes **Differential Count and Changes in Leukocyte Profiles** **a. A reduced number of leukocytes is leukopenia, which may increase the risk of developing an infection and decrease the ability to fight infection.** **b. A slightly elevated leukocyte count due to recent infection or stress is termed leukocytosis.** 38. **Discuss leukemia in general and its types.** **Leukemia**: A malignancy of leukocyte-forming cells, marked by abnormal proliferation of leukocytes, leading to anemia and increased bleeding. - **Acute leukemia**: Rapid progression, typically seen in children and young adults. - **Chronic leukemia**: Slow progression, seen more in middle-aged and older individuals **Leukemia is a malignancy of the leukocyte-forming cells. All types are marked by abnormal development and proliferation of leukocytes.** **Leukocyte numbers increase while erythrocyte and platelet numbers decrease, leading to anemia and bleeding. Leukemias are classified based on their duration as either acute or chronic.** 39. **Explain and discuss the platelets, termed the thrombocytes.** **Platelets (thrombocytes)**: Cellular fragments derived from megakaryocytes. They play a crucial role in blood clotting and are involved in the process of hemostasis **. Platelets (thrombocytes) are membrane-enclosed cellular fragments lacking a nucleus and constantly being produced by megakaryocytes in the red bone marrow.** **Platelets serve an important function in hemostasis as they become trapped within the fibrin network of a blood clot.** 40. **Explain the normal blood platelet count; define and explain thrombocytosis and thrombocytopenia.** - **Normal platelet count**: 150,000--400,000 per cubic millimeter of blood - **Thrombocytosis**: Increased platelet count, which can increase the risk of clot formation - **Thrombocytopenia**: Decreased platelet count, leading to an increased risk of bleeding Thrombocytosis: an elevated platelet count. Thrombocytopenia: a decrease in the platelet count out of normal range; this condition can lead to bleeding problems. 41. **Discuss the platelet's role in hemostasis.** Platelets are essential for blood clotting as they form a **platelet plug** and release chemicals that help in the coagulation cascade Platelets serve an important function in hemostasis as they become trapped within the fibrin network of a blood clot 42. **Explain and discuss the process of hemostasis.** **Hemostasis**: The stoppage of bleeding, involving three phases: - **Vascular spasm**: Constriction of blood vessels. - **Platelet plug formation**: Platelets stick to damaged vessel walls. - **Coagulation**: Formation of a fibrin clot Hemostasis: The process whereby blood clots and inhibits blood flow through an injured vessel is called hemostasis or stoppage of blood and has three phases 43. **Explain and discuss the purpose of hemostasis; explain the term cascade reaction and discuss the positive feedback nature of the hemostatic process.** - **Purpose**: To prevent blood loss after vascular injury. - **Cascade Reaction**: A series of enzymatic reactions that amplify the response, leading to clot formation. - **Positive Feedback**: The process is self-amplifying as each step accelerates the following one until the clot is formed **Hemostasis: The process whereby blood clots and inhibits blood flow through an injured vessel is called hemostasis or stoppage of blood and has three phases. (pp. 722--727)** **Formation of the platelet plug is an example of positive feedback and will continue until the plug is completely formed** 44. **Explain that the hemostatic process has three phases: vascular spasm, platelet plug formation, and coagulation (clotting).** The three phases of **hemostasis** are: The process whereby blood clots and inhibits blood flow through an injured vessel is called hemostasis or stoppage of blood and has three phases As platelets undergo these changes, their cytosol degranulates, releasing chemicals to assist in hemostasis by attracting more platelets. - **Vascular spasm** - **Platelet plug formation** - **Coagulation** 45. **Explain the vascular spasm and its specific role in the hemostatic process.** **Vascular spasm**: A sudden constriction of blood vessels, reducing blood flow and limiting blood loss at the site of injury **Vascular Spasm (p. 722--723); Figure 18.12a (p. 723)** **The process by which a damaged blood vessel constricts suddenly, restricting the amount of blood leakage from the vessel, is called vascular spasm.** **The vascular spasm phase usually lasts from a few to many minutes.** **The damaged blood vessel wall begins to release many chemicals to further stimulate the vascular spasm** 46. **Explain the platelet plug formation and its specific role in the hemostatic process.** **Platelet plug formation**: Platelets stick to exposed collagen fibers in the vessel wall and aggregate to form a temporary seal, blocking blood loss **Platelet Plug Formation (p. 723); Figure 18.12b (p. 723)** **Normally, the endothelial wall is smooth and coated with prostacyclin that inhibits platelet activity.** **Once the blood vessel wall is damaged, the collagen fibers within the connective tissue internal to the endothelial cells become exposed, and platelets begin to stick to the exposed collagen with the aid of a plasma protein called von Willebrand factor.** **As platelets stick to the vessel wall, they develop long processes that further adhere them to the vessel wall.** **As more and more platelets aggregate to the site, a platelet plug develops to close off the injury.** **This occurs in just a few minutes after the injury.** **As platelets undergo these changes, their cytosol degranulates, releasing chemicals to assist in hemostasis by attracting more platelets.** **Formation of the platelet plug is an example of positive feedback and will continue until the plug is completely formed.** 47. **Briefly define extrinsic pathway, intrinsic pathway, and common pathway. (you do not need to describe or list each clotting factor involved)** - **Extrinsic pathway**: Initiated by external tissue damage; faster process - **Intrinsic pathway**: Initiated by internal vessel damage - **Common pathway**: Both pathways converge, leading to the formation of fibrin to stabilize the clot **Coagulation Phase (pp. 724--727); Figure 18.12c (p. 723)** **Initiation of the Coagulation Cascade: blood clotting can occur by two separate mechanisms: the intrinsic (contact activation) pathway or the extrinsic (tissue factor) pathway. (Figure 18.13 p. 726); both pathways converge to the common pathway.** **a. The intrinsic pathway of coagulation is initiated by internal vessel wall damage.** **b. The extrinsic pathway of coagulation is initiated by external tissue damage and is a quicker pathway.** **c. The common pathway begins with the formation of a prothrombin activator from either the extrinsic or intrinsic pathway** 48. **Explain the general role of clotting factors in the entire coagulation process. What vitamin is needed to produce several clotting factors?** **Clotting factors**: Proteins that work together in a cascade to form a blood clot. **Vitamin K** is essential for producing several clotting factors **Substances Involved in Coagulation** **a. Blood coagulation requires many substances, including calcium, clotting factors, platelets, and vitamin K.** **c. Most clotting factors are inactive enzymes, and most are produced by the liver.** **d. Vitamin K is a fat-soluble vitamin needed to make several clotting factors** 49. **Explain the roles of prothrombin activator, prothrombin, thrombin, fibrinogen, and fibrin in the coagulation process. What ion is also involved in coagulation?** - **Prothrombin activator**: Converts prothrombin into thrombin. - **Thrombin**: Converts fibrinogen into fibrin. - **Fibrin**: Forms the structural framework of the blood clot. - **Calcium ions (Ca2+)**: Essential for various steps in the coagulation process **The common pathway begins with the formation of a prothrombin activator from either the extrinsic or intrinsic pathway.** **Prothrombin activator activates prothrombin to thrombin.** **Thrombin converts soluble fibrinogen to insoluble fibrin.** **In the presence of Ca2+, fibrin forms a polymer that serves as the framework of the clot.** 50. **Discuss the difference between an anticoagulant, like heparin, and a thrombolytic agent, like plasmin.** - **Heparin (anticoagulant)**: Prevents blood clot formation - **Plasmin (thrombolytic agent)**: Breaks down formed clots **Bleeding and Blood Clotting Disorders (p. 726)** **Anticoagulants like heparin are substances that prevent blood clotting, while thrombolytic agents like plasmin break down clots once they have formed.** 51. **Define the terms thrombus and embolus.** - **Thrombus**: A stationary blood clot within a vessel. - **Embolus**: A moving blood clot that can lodge in a smaller vessel A thrombus is a clot that forms within a blood vessel, while an embolus is a piece of a thrombus that has broken loose and is traveling through the bloodstream 52. **Explain and discuss various blood clotting disorders: hemophilia and thrombocytopenia.** - **Hemophilia**: A genetic disorder causing improper blood clotting due to missing clotting factors - **Thrombocytopenia**: A condition characterized by low platelet count, leading to excessive bleeding **Clinical View 18.8: Bleeding and Blood Clotting Disorders (p. 726)** **Hemophilia is a group of bleeding disorders caused by specific genetic mutations that cause certain clotting factors to function improperly.** **Thrombocytopenia is a decrease in the platelet count out of the normal range; this condition can lead to bleeding problems.**