Your PerspectiveBefore we begin to understand some of the actual experimental procedures that Dr. Leach and her team carried out, and before we present the results of those experiments, let's participate in a few activities that can help clarify certain important concepts and techniques related to her study. The first exercise is designed to provide you with practice in data interpretation. The data involved presents a comparison of measurements of certain components of both blood and urine. From this activity, you will understand the kinds of chemicals that: (1) are "washed out" of the blood and excreted by the kidneys, (2) that remain in the blood, or (3) that return to the blood from the kidney tubules through reabsorption. This activity will indicate which of these chemicals are important for the body to keep and which are important for the body to get rid of.
The second exercise will familiarize you with the particular technique used for the determination of glomerular filtration rate (GFR). This measurement of the rate at which the blood is filtered in the glomerulus is based on measuring how fast a certain chemical tracer is eliminated from the body. You will be participating in a demonstration activity known as a "serial dilution" that will serve as a model representation of how a tracer substance can be used to determine the elimination rate of the tracer, and thus, GFR. A model is often used in the scientific world to help demonstrate the principles of a particular technique without having to actually carry out the technique. For instance, you may have a model of some part of the human anatomy in your classroom. This model substitutes for the need to actually take a body apart to investigate some of the internal structures! The use of a model can also help you predict some kind of outcome in the real experiment that the model is representing. The value of a model in being able to predict outcomes, however, depends on how close the model actually comes to duplicating the real system. Keep in mind that this is only a demonstration exercise. There are some significant differences between the serial dilution technique and the technique that is used to measure GFR. By identifying those differences, your understanding of the GFR measurement technique will be enhanced.
The last exercise centers on the idea of developing a concept map to illustrate the relationships among the various responses of the body to microgravity. In particular, this exercise will tie together the cardiovascular, blood system, and renal/endocrine changes that occur due to the "upward" fluid shift that you are familiar with by now.
Let's begin our Student Investigations!