Urine formation and Urinalysis

Nephrons

Forms urine in each kidney and enablees the body to remove metabolic wastes rom blood and to maintain homeostasis by regulating water volume, concentration of ions in blood, and blood pH

What does urinalysis test?

volume of urine, physical, chemical, and microscopic composition of urine, level of metabolic wastes

What are the three processes nephrons use to produce urine?

Filtration, tubular reabsorption, tubular secretion

What is Filtration?

it is 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 re absorption

water and solutes cross the wall o the renal tubule, diffuse through the interstitial fluid, and return to blood by entering the peritubular capilaries 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 wall of theglomerular capsule) into the capsular space (glomerular cavity

Filtrate: definition?

filtrate, the liquid and solutes filtered into the capsular space, contains all the components of plasma except those that are too large to pass throug the pores in the filtration membrane-the blood cells, platelets and most proteins.

what is the rate of filtration across the glomerulus determined by?

blood pressure (hydrostatic pressure). the greater the pressure, the greater the filtration rate

What is urinalysis?

analysis of the physical, chemical, and microscopic characteristics of urine and a measure of uric volume

What does urine volume depend on?

it varies depending on water contend of the bodym and decreases when body fluid volume is low

What does ADH do?

acts on the collecting ducts to stimulate re-absorption of water from the filtrate

What happens to ADH if body fluid volume is high?

ADH is inhbited; the collecting ducts do not reabsorb water fromthe filtrate m and dilute urine is excreted

what is the "specific gravity of urine

the weight of a volume of urine divided by the weight of the same volume of distilled water.

what has a higher weight per volume? urine or distilled water?

urine weight per volume is higher than distilled water because of the presence of solutes in urine

T or F: normal urine contains 95% water and 5% solutes.

TRUE

Solutes found in normal urine include....?

electrolytes, urea, creantine, uric acid, metabolic end products

Normal VOLUME characteristics of urine

1-2 liters per 24 hours

Normal COLOR characteristics of urine

yellow or amber color; urine color is darker in concentrated urine

Normal TURBIDITY characteristics of urine

transparent in freshly voided urine; will turn cloudy after standing

Normal ODOR characteristics of urine

aromatic when fresh; ammnia-like after standing because of breakdown of urea to ammonia by bacteria

Normal pH characteristics of urine

normal range is 4.6-8.0 witha n average of 6.0; high protein diets produce an acidic urine; vegetarian diets produce an alkaline urine

Normal SPECIFIC GRAVITY characteristics of urine

normal range is 1.001-1.035; low specific gravity represents dilute urine,higher values represent a concentrated urine