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Functions of the Urinary System
removes wastes, stabilizes blood volume, acidity, & electrolytes, regulates extracellular fluids of the body, secretes hormones (erythropoietin & renini), & regulates absorption of calcium ions by activating Vitamin D
controls the rate of red blood cell formation
regulates blood pressure
the functional unit of the kidney which is located within the cortex and the medulla
Function of the nephron
filters waste substances from the blood and simultaneously maintain the essential water and electrolyte balance
Renal corpuscle
part of the nephron that contains the glomerulus and glomerular capsule
Glomerulus & Glomerular (Bowman's) capsule
the two structures of the renal corpuscle
made up of tangled blood capillaries. Appropriate sized substances are pushed through pores in capillaries into glomerular capsule (Bowman's) by hydrostatic pressure
Glomerular (Bowman's) Capsule
thin walled cup-shaped structure that surrounds the glomerulus and collects the substances filtered through the glomerulus
Renal tubules
composed of proximal convoluted tubules, nephron loop (loop of Henle), & the distal convoluted tubules
slender, muscular tubes, 10-12 inches long, & carry urine formed in the kidney to urinary bladder
Urinary bladder
hollow muscular organ that holds the urine until it is expelled (micturation)
tube that carries urine outside the body. Male--8" & Female 1.5"
fluids and dissolved substances (based on size) are forced through the glomerulus into the glomerular capsule by hydrostatic pressure creating a liquid called "glomerular filtrate"
some of the substances that flow through the renal tubules that are needed by the body cross back into the blood by the peritubular capillaries surrounding the tubules. Ex..glucose, water & electrolytes
substances are transported from the peritubular blood capillaries into the renal tubules. Ex..metabolized drugs, K+, & hydrogen ions
Renal threshold level
when blood levels of a substance such as glucose reach a point at which no more can be reabsorbed & it is excreted in the urine. The blood glucose renal threshold level is 160-180 mg/dL
Flow of Urine
Bloodstream:renal afferent arterioles--Glomerulus--Glomerular (Bowman's) capsule--Renal tubules--Collecting ducts--Renal pelvis--Ureter--Urinary bladder--Urethra--Urinary meatus (where urine is expelled)
makes up 95% of the substances in urine
Nitrogen waste products
urea, uric acid, ammonia & creatinine
urea, uric acid & ammonia are derived from the breakdown of this
Other waste products found in urine
chloride, Na+, K+, Ca++, Mg+, phosphate & sulfate
elements or compounds that form positively or negatively charged ions that when dissolved can conduct electricity
approximately the amount of blood that passes into the renal arteries per minute
daily output of urine a day. But can vary depending on the amt of intake of fluids and the amt lost from perspiration, feces, and water vapor in the lungs
decreased urine volume
increase in the volume of urine output
no flow of urine
painful urination
excessive urination at night
passing abnormally large amounts of urine
First morning specimen
most concentrated and formed over an 8hr period, volume at least 25mL
Renal cortex
the outer area of the kidney
Renal medulla
inner region of the kidney
Renal pelvis
funnel-shaped hollow are of the kidney
Reducing substances
substances that easily loses electrons
intact red blood cells in the urine
Bence Jones protein
protein found in the urine of patients with multiple myeloma
red cells breaking open and releasing hemoglobin
Specific gravity
in urinalysis, the weight of urine compared with the weight of an equal volume of water; measures the amount of dissolved substances in urine
sugars (especially glucose) in the urine
intermediate substance in the formation of heme (part of hemoglobin)
waste product from the breakdown of hemoglobin. Enters the liver where it becomes water soluble and most of this bilirubin is excreted through the gallbladder/intestines
white blood cells in the urine which indicates the presence of an infection in the genitourinary system, usually neutrophils
elements excreted in the urine in the shape of the renal tubules and ducts
scale that measures the level of acidity or alkalinity of a solution
Bacteria, cells, casts, mucus & crystals
substances that can cause urine to be cloudy and turbid
when strip is left in urine too long
products of fat metabolism and are acid. Need to correlate with pH
Conditions of ketonuria
fevers, starvation, anorexia, prolonged vomiting & diets high in fat and low in carbs
Blood in urine
can be from bleeding in the urinary tract caused by renal disorders such as stones, tumors, lesions, cystitis & urethritis
Three substances that can cause pad to be positive for blood
intact red cells, Hgb from hemolyzed RBC's, & Myoglobin
a substance like hemoglobin that transports oxygen in muscle tissue
120 days
the lifespan of a red blood cell. Then they are lysed and release Hgb
bilirubin must attach to this protein for transportation through the blood because it cannot pass through the glomerulus
Excessive hemolysis & Liver damage
conditions that cause excessive blood levels of bilirubin. Can also be associated with hepatitis
results from the breakdown of bilirubin in the intestines by bacteria. Normally can have small amounts in the urine
large amounts of protein in the urine and is one of the first signs of renal disease. Small amounts are normal in the urine because protein molecules are too large to pass through the glomerulus
critical for DM, Htn, MI, stroke, & pregnancy. Levels of 3.4-33.9 indicate microalbuminuria
measures the amount of acid and alkaline in urine and the amount of hydrogen ions in the urine. Normal urine has a pH of 4.5-8 with most healthy patients being 6.0
pH of 7
pH of 0-6
is acid
pH of 8-14
is alkaline
Lungs & kidneys
responsible for maintaining the body's acid-base balance
blood pH less than 7.35
blood pH greater than 7.45
Conditions that cause acid urine
diets high in protein, certain meds, uncontrolled DM, Renal tuberculosis
Conditions that cause alkaline urine
diets high in vegetables, citrus fruits, milk, and other dairy products, infection, metabolic disorders, meds, respiratory disorders, stale urine
in the urine can be converted to nitrites by some UTI's. 1st morning specimen best because it takes 4 hrs for this conversion
present in a urine specimen that contains bacteria which could be an indication of a UTI. When leukocytes are lysed the release esterase
Microscopic urinalysis
examines the urine sediment, counts, and categorizes the substances present. Not categorized at CLIA waived
material at bottom after spinning down urine
liquid above sediment after spinning down urine
Squamous epithelial cells
most frequently seen and least significant. Come from the lining of the vagina and lower portions of the male and female urethra. Cells are large and have abundant, irregular cytoplasm and a central nucleus the size of RBC's
Transitional epithelial cells
come from the lining of the renal pelvis , bladder, and upper urethra. Smaller than squamous, spherical, polyhedral or caudate (with tail), with a central nucleus
Renal tubular epithelial cells
the most significant of renal damage. Round and slightly larger than WBC's and can be distinguished from leukocytes by the presence of single round nucleus that if "OFF" center
are formed primarily within the distal convoluted tubule and collecting duct. Shapes are usually parallel sides and rounded ends
Factors that lead to cast formation
decreased urine flow, increased acidity, increased solute concentration, and increased plasma protein
Hyaline casts
consist almost entirely of Tamm-Horsfall protein and appear colorless in urine
Granular casts
contain coarse and fine granule casts throughout the matrix
formed by the precipitation of urine salts when changes in pH, temperature, or concentration occur, which can affect stability. pH is the most important aid in the identification of urine crystals
Amorphous urates crystals
yellow-brown granules, often in shapeless clumps. Give the urine a macroscopic pink "brick dust" color
Calcium oxalate crystals
looks like envelopes with an X on them
very tiny and must be viewed on high power. Appear as either rod shaped (bacilli)or round (cocci)
small, oval organisms that may bud from branches. Difficult to differentiate from RBC's but budding is helpful. Candida albicans may be found in urine of women with a vaginal infection
Trichomonas vaginalis
a protozoan flagellate. Most frequently seen parasite in urine specimens. Pear shaped with rapid darting movement. Sexually transmitted
How casts are reported
as the average number seen per low power field (lpf)
How cells are reported
using numeric ranges based on teh average per high power field (hpf)