M.+Urology

UROLOGY The study or urine? Or perhaps, what goes in, must come out or go somewhere?  **I. Kidneys **  *We have two of them (typically) *Each weighs about 160 grams *Main task is to regulate the extracellular fluid environment in our body, which contains plasma and interstitial fluid *Regulate the volume of blood plasma which is a major source of regulation of blood pressure *Regulates the concentration of waste products in our system *Regulates the concentration of electrolytes in the plasma and the pH of plasma *Divided into an inner medulla and outer cortex *Each kidney contains over a million nephrons *These nephrons have vascular and tubular components *Filtration takes place in the glomerulus *The cortex portion contains the Bowman's glomerular capsule and proximal and distal convoluted tubules *The medulla portion contains the loop of Henle media type="youtube" key="aQZaNXNroVY" height="351" width="432"

 *Sodium is actively transported in the body *Chloride is not far behing by electrical attraction *Water follows salt in our body out of the proximal tubule *About 65% of the filtered salt and water in our body is REABSORBED across the proximal convoluted tubules *The remaining water is reabsorbed mainly as a final product of the countercurrent multiplier system *Sodium in our body is EXTRUDED from our ascending lumb and right behind, following passively by the chloride *The ascending lump is actually impermeable to water so the rest of the filatration left becomes hypotonic *The interstitial fluid becomes hypertonic in the medulla because of the salt transport and the exchange in the vasa recta *A positive feedback mechanism plays a key role in the descending limb due to the hypertonic environment and becomes passively permeable to water and even salt *Next, the collecting ducts are permeable to water and not to salt *Osmosis takes place and the water leaves and is also carried away in the body by local capillaries *The antidiuretic hormone (ADH) is responsible for stimulating the permeability of the collecting ducts to the water
 * II. Reabsoprtion of Salt and Water **

 *Aldosterone is responsible for stimulating the sodium reabsorption and potassium secretion *This stimulation takes place in the cortical collecting duct and the late distale tubule *When the blood potassium rises it causes aldosterone to secrete *Aldosterone also secretes H+ and potassium into the filtration system for an exchange of sodium *The nephrons we talked about in the kidneys above are responsible of filtering bicarbonate and reabsorb the amount needed to have an equal acid-base balance in the body *The nephrons also filter and seceret H+ and execreted in the urine
 * III. Renal Control of Electrolyte and Acid-Base Balance **

**APPLICATION:** We have a Urology department in the hospital that I work at. We see a lot of kidney disorders and issues and treat them accordingly. We daily create special doses for patients who come in for dialysis. It is amazing that these people are able to continue their lives even with kidneys that do not work properly. However, the one thing I have learned is how time consuming and how often they have to do it, sometimes several times a week. There dedication to there diagnosis is amazing!! They are such patient and strong people.

__**Sources: **__ http://www.cartoonsbydave.com/GALLERY/IMAGES/urology.jpg http://www.childrensmemorial.org/depts/fetalhealth/images/Urology_NormalAnatomy_s.gif http://www.youtube.com/watch?v=aQZaNXNroVY