UROLOGYThis unit discusses the components of the kidneys, urinary tract and other structures within the urinary system and diseases associated with it.**Structure and Function of the Kidneys: The two kidneys lie on both sides of the vertabrae between the liver and diaphragm. The main function of the kidneys is to maintain a healthy environment of the extracellular fluid by forming and excreting urine. They also regulate the volume of blood plasma, concentration of waste products in the plasma, electrolytes and the pH of the plasma. Each kidney is encased in a layer of connective tissue known as the renal capsule and is divided into three regions: renal cortex, renal medulla and renal pelvis. Each Kidney contains about one million nephrons, which are the basic functional units of the kidneys. Within each nephron, there is a cluster of blood vessels knowns as the glomerus, which are then surronded by a hollow Bowman's capsule. The two together are known as the renal corpuscle, which empty into the collecting duct. When the collecting ducts and nephrons merge, they empty the blatter.http://www.chemistry.wustl.edu/~courses/genchem/Tutorials/Kidney/structure.htm
Reabsorption of Glucose: Glucose and amino acids are easily filtered through the glumeruli, but are not present urine when it is excreted. The reason being is that it is normally completely reabsorbed by the nephron through secondary active transport. Carrier-mediated transport occurs, meaning that the transported molecule (glucose) is present in high numbers, and all the carriers becoming occupied and the transport maximum is reached. In some conditions, such as diabetes, the glucose filtration rate will be greater than the transport maximum causing glucose to "spill over" into the urine. A urine test showing glucose can be a good tool in determining a diabetic condition.

Use of Diuretics: Patients with a high blood volume with conditions such as Congestive Heart Failure (CHF), edema and hypertension are often prescribed diuretics to lower the blood pressure by increasing the amount of urine excreted. Diuretics also decrease interstitial fluid volume. There are various types of diuretics and they all effect the nephron differently. The strongest types are loop or thiazide diuretics which inhibit salt and water reabsorption by 25%. Carbonic anhydrase inhibitors are the weaker ones, and they prevent water reabsorption that happens when the bicarbonate is reabsorbed. Osmotic diuretics work by increasing osmotic pressure of the filtrate and decreasin the reapsorption of water through osmosis.

**APPLICATION: As a student nurse, I feel like I have worked closely with the urinary system and the elimination process. Monitoring a patients I & O (input and output) is something with do with most of the hospital patients, especially when they are on IV fluid maintenance needs. Additionally, I view patient's lab reports to monitor their creatine and BUN. Descrepencies in either of these can mean renal problems or nephrotoxicity from certain medications ( ex. Aminoglycosides, Vancomycin). I have seen patients with renal failure and other complications of the urinary system. It's important to know the structure and how the system works in order to treat and understand their disorder and how certain medications help the cause. I also deal with incontinence and the use of foley catheters when needed. It's especially necessary to practice sterile technique when inserting, because a lot of noscomial infections are of the urinary tract (from the insertion of catheters). CRITICAL THINKING QUESTIONS
1. Describe the renal processes of filtration, reabsorption, secretion and excretion. Generally describe each process and then give a specific example of each process occurring in the nephron and/or urinary system.Filtration: Process in which solids are seperated from fluids (luquids or gases) by interposing a medium through which only fluid can pass. Ex: The glomerus uses three layers as filters to remove particles from the plasma. Reabsorption: The process of selectively absorbing a particle that has been previously absorbed. Ex: The reasorption of glucose which takes place by carrier-mediated transport. Secretion: The process of releasing a chemical substance which is usually specialized. Ex: Erythropoietin is released in response to hypoxia in the renal circulation. This stimulates erythropoeisis in the bone marrow. Excretion: The process used to discard waste from the body.Ex: After blood plasma has been filtered, the waste travels from the collecting duct and out the kidney in the form of urine.
2. Why is it so important to maintain a proper electrolyte balance? Give two examples. Maintaining a proper electrolyte balance is vital in maintaining homeostasis. Electrolytes all have a specific, important function in our bodies and abnormal levels can throw off their needed fuctions and jobs. They play extremely important roles in acid-base balance and fluid regulation. Electrolyte imbalances can cause a variety of health problems and if left untreated, can be fatal. Hyper/Hypokalemia (insufficient levels of potassium) can lead to cardiac arrythmias and sometimes cause cardiac arrest. Hypocalcemia (low levels of calcium) can cause cardiac issues, hypotension, seizures and muscle tetany.