Week 7 Lab: Urinalysis + Urinary Glomerular Filtration

What organs does the urinary system include?

kidneys, ureters, urinary bladder, urethra

What organ is blood filtered through?

the kidneys

What converts filtered fluid (filtrate) into urine?

the kidneys

What are the two mains functions of the kidneys in regards to the urinary system?

filters blood and converts filtrate into urine

By modifying process of urine formation, what 4 things can the kidneys influence?

blood volume, blood pressure, pH, blood concentration of substances

What transports urine from the kidneys to the urinary bladder?

ureters

What organ temporarily stores urine until it is eliminated from the body?

urinary bladder

What transports urine out of the body?

urethra

What are the two functions of the nephron?

filters blood and forms urine

What is the functional unit of the kidneys?

nephron

What are the two main parts of the nephron?

renal corpuscle and renal tubules

Where in the nephron is filtrate produced?

renal corpuscle

What is the “ball” of capillaries within the renal corpuscle?

glomerulus

What is the two-layered structure that encloses the glomerulus?

glomerular capsule

What is the space located between the two layers of the glomerular capsule?

capsular space

What is the main function of the capsular space?

collects filtrate as it is formed

What are the ducts that lead away from the glomerular capsule + location of tubular reabsorption and secretion?

renal tubules

What is the main function of the renal tubules?

reabsorbing nutrients, water, electrolytes back into the bloodstream + secreting waste products

What are the 3 processes involved in urine formation?

glomerular filtration

tubular reabsorption

rubular secretion

What occurs within renal corpuscle → some water & dissolved solutes are separated from blood plasma & captured as filtrate?

glomerular filtration

What occurs along the renal tubule → components within filtrate are transported across walls of tubule + into blood of nearby capillaries?

tubular reabsorption

What occurs along renal tubule → solutes are transported from blood to nearby capillaries & into tubular fluid for elimination?

tubular secretion

What is blood pressure within glomerulus with OUTWARD force that FAVORS filtration? → drives water & solutes out of the blood & into capsular space?

glomerulus hydrostatic pressure (HPg)

What is fluid pressure from filtrate within capsular space with INWARD force that OPPOSES filtration?

capsular hydrostatic pressure (HPc)

What is osmotic pressure exerted by proteins in the blood within the glomerulus with INWARD force that OPPOSES filtration?

blood colloid osmotic pressure (OPg)

What is the combination of the pressure associated with glomerular filtration?

net filtration pressure (NFP)

When does filtration occur?

If pressure promoting filtration (HPg) is LARGER than opposing forces (HPc & OPg) combined

What is the value of filtered fluid produced per unit time?

glomerular filtration rate (GFR)

What does rate of glomerular filtrate rate (GFR) have a significant influence on?

blood volume, blood pressure, & amount of substances reabsorbed and secreted

What 2 things regulate glomerular filtrate rate (GFR)?

intrinsic control (kidneys)

extrinsic control (hormones and nervous system)

What vessel carries blood TO the glomerulus of a nephron?

afferent arterials

What vessel carries blood AWAY from the glomerulus of a nephron?

efferent arterials

What is the barrier which substances must pass through during filtration?

filtration membrane

What are the 3 things the filtration membrane consists of?

glomerular capillary endothelium, basement membrane, & filtration slits of podocytes

What are then cells sitting atop glomerular capillaries that form the inner layer of the glomerular capsule?

podocytes

How are filtration slits formed?

extensions of neighboring podocytes interlocking = filtration slits

What is intrinsic control of GFR?

regulation mechanism contained within the kidneys

What is extrinsic control of GFR?

regulatory mechanism initiated by hormones and nervous system

What are specialized smooth muscle cells of afferent arterials that secret renin when stimulated by nervous system?

granular (juxtaglomerular) cells

What cells are located in spaced within the glomerulus that contract and relax to alter surface area of the filtration membrane?

intraglomerular mesangial cells

What is the enzyme released by granular cells in response to a drop in blood pressure & stimulates production of angiotensin II?

renin

What is the hormone that acts to restore blood volume & pressure → contracts mesangial cells to reduce GFR?

angiotensin II

What hormone is released by the heart in response to elevated blood pressure (acts to lower blood volume & blood pressure) → relaxes mesangial cells to increase GFR?

Atrial Natriuretic Peptide (ANP)

When mean arterial blood pressure increases to a high value, what occurs to ensure blood pressure in the glomerulus does not get too high?

the afferent arterials decrease in diameter (vasoconstriction)

What are the 4 substances can freely cross the filtration membrane?

ions, water, urea, & glucose

What is the equation for net filtration pressure?

HPg- (OPg + HPc)

Which conditions will decrease net filtration pressure?

decreased glomerular hydrostatic pressure (HPg)

increased capsular hydrostatic pressure (HPc)

When MAP increases, afferent arterials _______, ensuring pressure in the glomerulus does not get too _____?

vasoconstrict (get narrow); high

What effect does the constriction of afferent arterials have on filtration surface area?

decreases filtration surface area

A patient being treated for high bp, based on its effects on GFR, which could be administered to decrease bv & bp?

atrial natriuretic peptide (ANP)

Individuals with liver disease have plasma protein concentration that is lower than normal, what pressure is reduced as a result of lower plasma protein?

blood colloid osmotic pressure

Compared to normal, what will happen to net filtration and glomerular filtration rate if there is lower plasma protein?

both net filtration & glomerular filtration rate will increase

What mechanism does the body use to maintain normal blood composition?

urine formation

How much urine does the body produce a day?

0.5 liters of urine per day

What is the amount of urine produced based on?

fluid intake, blood pressure & temperature

What percent of the filtrate created will be reabsorbed during the process of urine formation?

99%

What is urine characterized by during a urine analysis?

composition, volume, specific gravity, color, transparency, smell

What is an easy, non-invasive and quick way to determine if there are disease/infections present in the urine?

urine analysis

What are the 4 important safety precautions to take during urine analysis?

• wash lab before & after procedure w appropriate disinfectant

• wear gloves, coat, goggles

• dispose of urine contaminated items in hazardous waster container

• wash hands after lab

What does normal fresh urine look like?

clear & pale yellow

What does dark-yellow urine suggest?

urine may be more concentrated

What does cloudy urine suggest?

presences of infection

What is the urine pH range?

What is the typical pH of urine?

range: 4.5-8

typical: 6

What type of urine is sterile, formed form filtered blood, mostly water, has solutes, has nitrogenous wastes, some hormones, small amounts of ketones?

normal, healthy urine

What does the presence of glucose, RBCs, WBCs, excess protein, or excess ketones indicate?

infection/disease

What type of urinalysis is a speciality stick with chemically treated pads?

dipstick urinalysis

What is the cloudiness of a solution called?

turbidity

What are part of the immune system and not normally found in urine → presence = infection

leukocytes

What is normal in small amounts in the urine → excess is called proteinuria & indicates kidneys are not working correctly?

protein

What is the measure of concentration of hydrogen ions in a solution → measures acidity/alkalinity and typical in urine is 6?

pH

What are the 2 reasons why pH may vary?

diet & infection

What contains RBCs, WBCs, & platelets that are not normally found in the urine → presence indicated infection/disease?

blood

What fills RBCs and functions to transport gases throughout the body → presence means blood is present in the urine?

hemoglobin

What is the compound produced during fatty acid metabolism and can easily pass through filtration membrane of nephron → not normally founding urine → presence = disease (like diabetes)

ketones

What is a common monosaccharide the body uses for ATP and is completely reabsorbed form filtrate → presence in urine = typical in diabetes?

glucose

The pads on urinalysis stick contains what?

regents that react with solutes

The patient has clear urine, what might this indicate?

clear color urine may indicate more diluted urine

If a patient has cloudy urine, what could this indicate?

urinary tract infection

Why is it important to wait 60 seconds before reading urine value?

allow adequate time for urine to react with each test pad

Which specific part of the kidney is urine formed in?

nephron

What are not normally found in urine?

leukocytes, blood, glucose, protein