The urinary system part 2

The structure of urinary part and function
Formation of a concentrated urine occurs in response to the release of antidiuretic hormone, which makes the collecting ducts permeable to water and increases water uptake from the urine.

•Diuretics act to increase urine output by either acting as an osmotic diuretic or by inhibiting Na+ and resulting obligatory water reabsorption.
11 Define renal clearance and explain how this value summarizes the way a substance is handled by the kidney.
•Renal clearance refers to the volume of plasma that is cleared of a specific substance in a given time.

•Inulin is used as a clearance standard to determine glomerular filtration rate because it is not reabsorbed, stored, or secreted.

•If the clearance value for a substance is less than that for inulin, then some of the substance is being reabsorbed; if the clearance value is greater than the inulin clearance rate, then some of the substance is being secreted. A clearance value of zero indicates the substance is completely reabsorbed.
12 Describe the normal physical and chemical properties of urine.
•Physical Characteristics
oFreshly voided urine is clear and pale to deep yellow due to urochrome, a pigment resulting from the destruction of hemoglobin.
oFresh urine is slightly aromatic, but develops an ammonia odor if allowed to stand, due to bacterial metabolism of urea.
oUrine is usually slightly acidic (around pH 6) but can vary from about 4.5–8.0 in response to changes in metabolism or diet.
oUrine has a higher specific gravity than water, due to the presence of solutes.

•Chemical Composition
oUrine volume is about 95% water and 5% solutes, the largest solute fraction devoted to the nitrogenous wastes urea, creatinine, and uric acid.
13 List several abnormal urine components, and name the condition characterized by the presence of detectable amounts of each.
•Glucose – Glycosuria, caused by Diabetes Melitis

•Proteins – Proteinuria, caused by excessive exertion, pregnancy