Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Anatomy & Physiology A White Blood Cell Study: The Differential WBC Count The blood is an opaque, rather viscous fluid that is bright red when oxygenated and dark red when depleted of oxygen. Its specific gravity is normally 1.06 and its pH is slightly alkaline (pH > 7). When centrifuged, blood becomes separated into a dark red portion made up of formed elements and a clear straw-colored portion called plasma. The formed element content of blood is around 47% in men and 42% in women. During this lab exercise, you will study the leukocytic portion of the formed elements in blood. This study will involve prepared blood slides. The formed elements of blood consist of erythrocytes (red blood cells), leukocytes (white blood cells), and blood platelets. Erythrocytes are non-nucleated cells with depressed centers that contain hemoglobin. (Their shape resembles the Werther's caramel candy) RBCs are the most numerous element in blood - around 4.5 to 5.5 million cells per cubic millimeter!! The leukocytes are of two types: granulocytes and agranulocytes. The granulocytes are so named because they have conspicuous granules in their cytoplasm. Neutrophils, eosinophils, and basophils fall into this category. The agranulocytes lack pronounced granules in the cytoplasm; the monocytes and lymphocytes are of this type. The blood platelets are noncellular elements in the blood that assist in the clotting process. In this lab exercise, the formed elements will be examined in an attempt to determine the percentage of each type of leukocyte on a slide. By scanning an entire slide and counting the various types, you will have an opportunity to encounter most, if not all, types. The erythrocytes and blood platelets will be ignored. The main purpose of this exercise will be to learn how to distinguish the various types of white blood cells, not to become proficient in performing differential WBC counts. The normal percentage ranges for the various leukocytes are as follows: Neutrophils Lymphocytes Monocytes Eosinophils 50-70% 20-30% 2-6% 1-5% Basophils 0.5 - 1% "Never Let Monkeys Eat Bananas" is an easy pneumonic device to help you remember the relative abundance of each type of leukocyte. ** Because of the extremely low percentages of eosinophils and basophils, it is necessary to examine at least 100 leukocytes to increase the possibility of encountering one or two of them on a slide. Deviations from the above percentages may indicate serious pathological conditions. High neutrophil counts, or neutrophilia, often signal localized infections such as appendicitis or abscesses in some part of the body. Neutropenia, a condition in which their is a marked decrease in the number of neutrophils, occurs in typhoid fever, undulant fever, and influenza. Eosinophilia (high eosinophil count) may indicate allergic conditions or invasions by parasitic roundworms such as Trichinell spiralis, the pork worm (be sure to thoroughly cook all pork products!!!) Counts of eosinophils may rise to as much as 50% of the total leukocytes in cases of trichinosis. High lymphocyte counts (> 10,000 per cubic millimeter), or lymphocytosis, are present in whooping cough and some viral infections. A total WBC count below 5,000 per mm3 of blood is called leukopenia (a form of neutropenia) and may indicate the conditions of AIDS, measles, mumps, or chicken pox. A white cell count that determines the relative percentages of each type of leukocyte is called a differential white blood cell count. It is this type of a count that will be performed here. PROCEDURES: 1. Obtain a prepared blood slide. You will notice that the slide may be titled "Wright's Stain" - this is only to indicate what type of stain was used in preparing the slide. 2. Scan the slide with the low-power objective to find an area where cell distribution is best. A good area is one in which the cells are not jammed together or scattered too far apart. 3. Once an ideal area has been selected, switch to the high-power objective. 4. Systematically scan the slide, following a path going down, across, up, across, down, etc... As each leukocyte is encountered, identify it using your notes, text book, or histology atlas for assistance. 5. Neatly tabulate your count in a data table and include with your review questions. 6. Examine and perform a differential WBC count on a prepared slide of mononucleosis or leukemia. Include your results in your data table. REVIEW QUESTIONS: (Answer on a separate sheet of paper) 1. Include a detailed sketch of each of the five types of white blood cells. Describe the function of each type of leukocyte under your sketch. 2. A normal red blood cell count for males is around 5,400,000 cells per mm3 and aroiund 4,600,000 cells per mm3 for women. What is the function of the RBC, and why do indigenous people of the himalayas have a RBC higher than average? 3. Why would an elevated WBC count indicate a potential health problem? 4. If a patient with an inoperable cancer takes a drug that reduces the rate of cell division, how might the patient's WBC count change? How could the patient's environment be modified to compensate for the effects of these changes? 5. What is erythropoietin? A synthetic form is available as a drug - why would athletes abuse it?