YOUR PERSPECTIVEBefore describing some of the actual experimental procedures that Dr. Alfrey and his team carried out, it is important for you to understand more clearly some of the scientific techniques and concepts related to his study. The first exercise has been designed to provide you with background and basic information about hematocrit. You will be given some specific information about how certain conditions affect a person's hematocrit. Then you will be asked to use that information to match certain hematocrits with certain described individuals.The second exercise will familiarize you with the concept of concentration. You will see how measuring the concentration of a dye in a liquid can help determine the volume of that liquid. The third exercise will use what you learned in the second exercise to explain how to determine how quickly RBCs are produced in the bone marrow. RBC production rates are determined by a radioactive marker (or tracer) method that utilizes the concept of concentration. Low levels of radioactivity, when used in controlled situations, can be a valuable research tool for the determination of various rates and volumes within the body. Dr. Alfrey's investigation utilized three different radioactive elements to accomplish various measurements for his study. In the third Student Investigation, a specific technique will be described that uses a radioactive marker to actually "mark" or "target" certain cells in order to determine the efficiency of RBC production in the bone marrow. The changes in concentration of these markers over time will give important information about the rate at which the marker is being utilized in the body. You will carry out a graphical analysis of the results from this technique. None of the Student Investigations are difficult. Keep in mind that all three of the activities relate to actual situations that occur every day in many laboratories around the country. Enjoy your journey!
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