1.) What is the significance of lower-than-normal hematocrit?
Lower-than-normal hematocrit indicates anemia. People with anemia do not have enough hemoglobin, which is the oxygen-carrying protein in red blood cells. Iron, B12, and folic acid deficiencies, some medications, and pregnancy can cause anemia. There are also more serious causes such as problems with the immune system that cause destruction of red blood cells earlier than normal, chronic diseases including kidney disease and cancer, and problems with bone marrow found in leukemia and lymphoma (MedlinePlus:Anemia, 2012). What is the effect of a bacterial infection on the hematocrit?
A bacterial infection, which raises white blood cell counts, may affect the hematocrit by lowering it. 2.) Compare the development of lymphocytes with the development of the other formed elements.
Lymphocytes and the other formed elements are developed from pluripotent stem cells. The pluripotent stem cells generate myeloid stem cells and lymphoid stem cells. Myeloid stem cells start and complete their development in red bone marrow and give rise to red blood cells, platelets, eosinophils, basophils, neutrophils, and monocytes. Lymphoid stem cells begin development in the red bone marrow, but some are completed in the lymphatic tissues, where they give rise to lymphocytes. The B cell lymphocytes are began and completed in the red bone marrow and the T cell lymphocytes begin in the red bone marrow, but they mature in the thymus (Jenkins, Kemnitz, & Tortora, 2010).
3.) What is erythropoiesis?
Erythropoiesis is the production of red blood cells or erythrocytes. It starts in the red bone marrow with a proerythroblast. The proerythroblast divides many times and produces cells that begin to make hemoglobin. A cell near the end of the development cycle ejects its nucleus and then becomes a reticulocyte. Reticulocytes pass from red bone marrow into the bloodstream. Reticulocytes develop into erythrocytes with 1 to 2 days after they are released from the bone marrow (Jenkins, Kemnitz, & Tortora, 2010). Which factors speed up and slow down erythropoiesis?
Oxygen deficiency (hypoxia) detected by the kidneys increases erythropoiesis. This stimulates the kidneys to release more erythropoietin. It circulates through the blood to the bone marrow and speeds up the production of proerythroblasts into reticulocytes.
Erythropoiesis slows down when there is sufficient oxygen delivery to the kidneys and tissues (Jenkins, Kemnitz, & Tortora, 2010). 4.) Explain what would happen if a person with type B blood were given a transfusion of type O blood.
Type O blood carries neither antigen A nor antigen B and is known as the “universal donor” because of this. Therefore, there would be no negative reaction if a person with type B blood were transfused with type O blood (Jenkins, Kemnitz, & Tortora, 2010). 5.) During an anatomy and physiology exam you are asked to view white blood cells in prepared slides of standard human blood smears. Based on the observations below, what is the name and function of each WBC? a.) WBC has a round nucleus surrounded by a blue halo of cytoplasm with no visible granules.
These are lymphocytes (T cells, B cells, and natural killer cells). Lymphocytes mediate immune responses, such as antigen-antibody reactions. B cells develop into plasma cells, which then secrete antibodies. T cells attack viruses, cancer cells, and transplanted tissue cells. Natural killer cells attack a variety of infectious microbes and certain tumor cells. b.) WBC contains dense blue-purple granules that hide the nucleus.
This WBC is a basophil and makes up 0.5-1% of the total WBCs. Where there is inflammation, basophils leave the capillaries. They enter tissues, and release histamine and heparin. These substances make inflammatory reactions greater and are involved in allergic reactions. c.) WBC has a U-shaped nucleus and a bluish, foamy cytoplasm with no visible granules.
These are monocytes, making up 3-8% of WBCs. They migrate from the blood into tissues, enlarge, and then become macrophages. Some become fixed macrophages and live in a particular tissue, such as the lungs and spleen. Others become wandering macrophages and gather at infection and inflammation sites. They gather at infection sites in large numbers and phagocytize microbes. They also clean up cellular debris after an infection. d.) WBC contains small, pale lilac granules and a four-lobed nucleus.
This type is a neutrophil and makes up 60-70% of WBCs. Neutrophils arrive at an infection site the quickest of all WBCs. After they ingest a pathogen, neutrophils release chemicals to destroy that pathogen. These chemicals include lysozyme, hydrogen peroxide, and hypochlorite. Neutrophils also contain defensins, which are a protein that poke holes in the membrane of the microbe and kills it. e.) WBC contains red-orange granules and a two-lobed nucleus.
This is a sample of an eosinophil and they represent 2-4% of all WBCs. Eosinophils leave the capillaries and enter the tissue fluid where they release enzymes that combat allergic reactions. They also phagocytize antigen-antibody complexes and fight parasitic worms. A high eosinophil count would most likely indicate an allergy or a parasitic infection (Jenkins, Kemnitz, & Tortora, 2010). 6.) Why would the level of leukocytes be higher in an individual who has been infected with a parasitic disease?
A parasitic disease is a stressor in the body. It is a normal, protective response for the number of leukocytes to increase in this situation because the blood is producing more leukocytes to fight the parasite. 7.) In regions where malaria is endemic, some people build up immune resistance to the malaria pathogen. Which WBCs are responsible for the immune system response against pathogens? How do they function?
Eosinophils are the WBC responsible for immune system response against pathogens. Eosinophils leave the capillaries and enter tissue fluid where they release enzymes. They phagocytize antigen-antibody complexes and fight parasitic infections
(Jenkins, Kemnitz, & Tortora, 2010).
8.) What is the function of prothrombinase and thrombin in clotting? Explain how the extrinsic and intrinsic pathways of blood clotting differ. The extrinsic pathway of blood clotting occurs rapidly, within a matter of seconds. A tissue protein called tissue factor enters into the blood from damaged tissue cells outside (extrinsic) blood vessels. Tissue factor then begins a series of reactions that lead to the formation of prothrombinase. The intrinsic pathway occurs more slowly, over the course of several minutes. The activators of this pathway are in direct contact with blood or contained within (intrinsic) the blood. Again, after a series of reactions, prothrombinase is formed.
Once the prothrombinase is formed it converts prothrombin (a plasma protein formed by the liver) into the enzyme thrombin. Thrombin, together with calcium ions, converts fibrinogen to fibrin threads and activates a clotting factor that strengthens the fibrin threads into a clot. A positive feedback cycle begins with the formation of thrombin. Thrombin activates more platelets, which increases the release of platelet phospholipids, which then increases the formation of prothrombinase. Thrombin also directly accelerates the formation of prothrombinase. The additional amount of prothrombinase accelerates the production of thrombin. The positive feedback loop continues and the fibrin clot grows (Jenkins, Kemnitz, & Tortora, 2010).
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