The kidney are organs that are responsible for filtering the blood and making urine. Urine, of course, is a waste product, you need to filter the bad stuff out of your blood and save it somewhere until you are ready to get rid of it (preferably in the bathroom). The structure and function of the kidney cells are closely related. Function follows structure after all.
Every one has a pair of kidneys. They are located about midway down your abdomen, on either side of your body, approximately below the lungs. They are a little toward the back as well.
Kidneys receive a large percentage of the total blood flow through the body. As the blood flows through the kidneys, specialized cells filter out a variety of waste products. The filtration system in the kidneys is rather complicated. The primary filtration unit of the kidney is the glomerulus. There are literally thousands of these in each kidney.
After entering the glomerulus, the first part of the filtration system is called the proximal tubule. The cells in this part of the kidney remove glucose, amino acids, and sodium from the filtrate. In the process, the filtrate sets up a chemical gradient which becomes important in later stages of the filtration process.
After passing through the proximal tubule, the filtrate enters the Loop of Henle. There is a descending and ascending Loop of Henle. The Loop penetrates deep in to the tissues of the kidney. As the filtrate passes through the Loop, chemical gradients help to remove various chemicals at various parts of the process. The details of what is removed where is somewhat complicated and is often best described with the use of diagrams and pictures (which can’t be done here).
After the Loop of Henle is the distal tubule. Again, more chemicals are filtered both in and out of the the filtrate. Sodium and water are removed in this part.
The last part of the filtration system is the collecting duct. In this part of the filtration, the last of the water is concentrated out – making urine have as little water as possible. At each phase of this process, there are medications which have been developed to block or assist the process. Diuretics are chemicals (both natural and man-made) that act mostly on the collecting duct, allowing more water to pass out of your body.
After all the filtration is done, the urine which is formed is passed on to the ureters and ultimately to the bladder where it is stored until you use the restroom. Bear in mind that this is but a very simple overview of the structure and function of kidney cells. The actual process is extremely complicated, and often fills entire chapters in anatomy and physiology text books. Hopefully this gave you at least a start in understanding the process of urine formation.
