Name & Section Physiology Lab 12: Urine Formation & Urinalysis (Adapted from SI.
ID: 3515856 • Letter: N
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Name & Section Physiology Lab 12: Urine Formation & Urinalysis (Adapted from SI. Fox, A Labraory Guide to muman Plosioloy. 13 edition, C. Allen and V. Haer Clinical Investigation A student performed a elinical own urine and found trace amounts of glucose and proteins. There was also mild hematuria. She found no casts when she examined her urine sediment, but did see rod-shaped bacteria and white blood cells. examination of her Introduction The formation of urine by the I million nephrons in each kidney enables the body to remove metabolic wastes from blood and to maintain homeostasis by regulating water volume, concentration of ions in blood, and blood pH. A urinalysis is a simple test that can determine if urine formation is normal or abnormal. This test analyzes the volume of urine, and the physical. chemical, and microscopic composition of urine. In addition, the level of some metabolic wastes in the blood is assessed. Function of the Nephron Urine is produced by the nephron and collecting ducts through three different processes glomerular filtration, tubular reabsorption, and tubular secretion. Filtration-The first step in urine production. Water and most solutes in blood pass through the filtration membrane (glomerular capillary walls and visceral wall of glomerular capsule) into the glomerular cavity Tubular reabsorption-Water and solutes cross the wall of the renal tubule, diffuse through the interstitial fluid, and return to blood by entering the peritubular capillaries or vasa recta. Tubular secretion Solutes leave the peritubular capillaries or vasa recta, diffuse through the interstitial fluid, cross the wall of the renal tubule, and are eliminated in urine. In the kidneys, blood is filtered across the filtration membrane (capillary walls and the visceral that are too large to pass through the pores in the filtration membrane--the blood cells, platelets, Also, filtrate moves by hydrostatic pressure into the first section of the renal tubule, the proximal wall of the glomerular capsule) into the capsular space (glomerular cavity). Filtrate, the liquid and solutes filtered into the capsular space, contains all the components of plasma except those and most plasma proteins. The rate of filtration across the glomerulus is determined by blood pressure (hydrostatic pressure). The greater the blood pressure, the greater the filtration rate. convoluted tubule. A urinalysis is an analysis of the physical, chemical, and microscopic characteristics of urine and a measure of urine volume. The normal characteristics of urine are listed in Table 37.3 on the next page. Urine volume varies depending on the water content of the body, and decreases when body fluid volume is low. ADH secreted by the posterior pituitary gland acts on the collecting ducts to stimulate reabsorption of water from the filtrate. If body fluid volume is high, ADH secretion is inhibited, the collecting ducts do not reabsorb water from the filtrate, and dilute urine is excreted. The specific gravity of urine is the weight of a volume of urine divided by the weight of the same volume of distilled water. Urine weight per volume is higher than di water because of the presence of solutes in urine. The more solutes present in ur the specific gravity. Normal urine contains 95% water and 5% solutes. The solutes found in normal urine include electrolytes (sodium, potassium, chloride, and other ions), urea (form ne, the higher edExplanation / Answer
Answer of Review and Application questions:
1. Normal urine output for an adult per day is 800 ml to 2000 ml.
2. Urine can become cloudy because of dehydration or presence of pus and blood caused due to any infection in urinary bladder, urethra, etc. Presence of protein can also make urine cloudy. Microbes, Epithelial cells and crystals also make urine cloudy.
3. Five Solutes found in urine are, urea, uric acid, creatinine, sodium chloride, carbohydrates etc.
4. Normal urine contains 95% water and 5% solutes.
5. Urine casts are Substances found in urine which are microscopic. They are formed because of precipitation of some proteins like albumin and mucoprotein in the cases of proteinuria.
Calculi in urine are solid particles which are kidney stones formed due to calcium oxalate, calcium phosphates, uric acids, etc.
The presence of cast and calculi in urine is abnormal which indicates disease state of kidney.
6. False.
Normal Urine is sterile and it does not contain bacteria. Sometimes bacteria may be present in very less number but they are asymptomatic and harmless.
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