Ch. 13 Urinary System

Renal corpuscle components

Glomerulus, glomerular capsule, afferent and efferent arterioles

Renal tubule components

Proximal convoluted tubule, nephron loop, and Distal convoluted tubule

Ureters

tubular structures that propel urine from the kidneys to the bladder through peristalsis, aided by gravity.

Urinary bladder

a muscular sac that stores urine temporarily.

Urethra

A tube-like structure that allows urine to pass out of the body through an orifice. The urethra is short in females and longer in males.

Functions of the urinary system

Excreting waste, reserving fluid, regulating acid-base balance and electrolytes, regulating blood cell production, maintaining normal blood pressure.

Filtration

Excess fluids and electrolytes in the blood filtering through the tiny capillaries in the glomerulus and into the Bowman’s capsule as filtrate

Reabsorption

Movement of fluids and substances such as glucose from the filtrate into the body through the tubules, based on renal threshold

Secretion

Transport of molecules and ions from the tubules to the filtrate (urine)

Elimination

Removal of the filtrate containing urea and other waste products from the kidneys, temporary storage in the bladder, and voiding

Reabsorption location

PCT, Loop of Henle

What is reabsorbed?

Most of the water is reabsorbed into the blood

Secretion location

DCT

What is secreted?

Metabolic wastes, electrolytes, ions, drugs, urea

Kidneys

red-brown bean-shaped organs. They are glandular and located posterior to the peritoneum, which is the retroperitoneal region and against the muscles of the back.

Renal artery and vein

The renal artery helps in delivering blood to the two kidneys. The renal vein helps in returning the blood from the kidneys to the larger veins.

Where are nephrons?

the outer layer of the kidney—the cortex.

Dysuria

difficult or painful urination

Urethritis

Inflammation of the urethra. Symptoms include discharge of pus, an itching sensation at the opening of the urethra, and burning during urination.

Cystitis

inflammation of the bladder. Symptoms include mild to acute discomfort in the lower abdomen, urinary frequency, and dysuria.

Pyelonephritis

inflammation of the renal pelvis and kidney due to infection. Symptoms include fever, chills, nausea, vomiting, and flank (lateral lumbar) pain.

Glomerulonephritis

an acute or chronic inflammation of the glomeruli. Symptoms include low-grade fever, anorexia, general malaise, and flank pain.

Hydronephrosis

may occur due to blockage, an enlarged prostate, or a tumor.

Urinary incontinence

Common causes include urinary tract infections (UTIs), brain disorders, and pelvic floor tissue damage. Damaged pelvic floor tissue may cause stress incontinence

Renal calculi (kidney stone)

Signs and symptoms include severe flank pain; hematuria; cloudy, foul-smelling urine; nausea and vomiting; urinary urgency; and fever and chills.

Acute renal failure

an abrupt decline in kidney function. It is caused by toxic chemical exposure, heart disease, kidney infection or inflammation, or complications from surgery.

Chronic renal failure

a progressive loss of kidney function. The causes of chronic renal failure include diabetes mellitus, hypertension, glomerulonephritis, polycystic kidneys, chronic hydronephrosis, lead poisoning, or renal artery stenosis.

Dialysis

the process of filtering the blood by removing waste and excess water when there is a loss of kidney function.

Hemodialysis

a process that works by using a machine called a dialyzer, or artificial kidney.

Peritoneal dialysis

filters the blood by using the capillaries of the peritoneal cavity.

Wilms’ Tumor

a rare type of kidney cancer that usually occurs by the age of three.

Nocturnal enuresis

Involuntary urination at night, after the age when a person is able to control the bladder (typically by the age of six). Involuntary urination during the day by the age of six is primary enuresis.

Secondary enuresis

may develop in children who have been dry for at least six months but who revert to wetting due to stress, UTIs, diabetes, or sex*al abuse.

Urinary reflux disorder

A backward flow of urine from the urinary bladder to the kidneys

Cryptochidism

an abnormality of male sexual development. It may occur when the testicles fail to descend to the scrotum before birth.

Kidney Ureter Bladder (KUB) X-ray

Determines the size, shape, location, and any malformations of the kidney and bladder. It can also detect calculi.

Renal scanning

Determines the size, shape, and function of the kidney and helps diagnose obstructions. The procedure involves intravenous administration of a radioisotope.

Intravenous pyelography or urography

Helps in the diagnosis of tumors, calculi, obstructions, and congenital renal problems. The procedure involves the injection of dye intravenously and taking X-ray films at intervals to help determine the passage of urine through the kidneys and ureters and into the bladder.

Cystography and voiding

The test helps to visualize the structure and function of the bladder. The procedure involves the use of contrast dye. X-ray images can also be taken while the patient is voiding (cystourethrogram).

Renal CT

The test helps in detection of tumors, abscesses, cysts, and hydronephrosis, using transverse views of the kidneys.

Uroflowmetry

This test helps to evaluate the function and flow of the lower urinary tract. The procedure involves using a measuring instrument to calculate urine quantity, the rate of flow in seconds, and the time taken to complete the void.

Renal ultrasonography

The test aids in the diagnosis of tumors, abscesses, cysts, and hydronephrosis. The procedure can be performed with or without the use of dye and involves taking transverse views of the kidneys.

Arteriography

The test allows for visualization of the blood flow in the kidney. It is used to diagnose renal artery stenosis and vascular renal cancers. The procedure involves injecting a dye into the renal artery to visualize it through a computed fluoroscopy.

Cystroscopy

The test helps to measure bladder capacity, diagnose cancer, diagnose and remove kidney calculi, dilate the urethra and ureters, and for placement of ureteral stents. The procedure involves using a cystoscope to visualize and biopsy the urethra and bladder.

Retrograde pyelography

The test helps to diagnose kidney calculi and other obstructions. The procedure involves injecting a dye through a cystoscope into the bladder, ureters, and kidneys.

Random specimen

The collection of freshly voided urine in clean containers

First-morning specimen

The specimen that the provider orders to collect when the patient wakes up in the morning (most concentrated)

2-hour postprandial urine specimen

The collection of urine two hours after a meal, which is useful for screening for diabetes using home testing programs

24 hour urine specimen

The collection of urine over 24 hours to provide a quantitative chemical analysis, such as hormone levels and creatinine clearance rates

Second-voided urine

A specimen that determines glucose levels

Clean-catch midstream specimen

A specimen that a provider orders during suspicion of a urinary tract infection and when there is a need for culture

Nonsterile containers

Useful for a random specimen, first-morning specimen, 24-hour urine specimen, and 2-hour postprandial specimen

Special pliable polyethylene bags

Useful for collecting urine from infants and children who do not have toilet training

Wide mouth plastic containers

Useful for collecting specimens over a specified period

Sterile containers

Useful for collecting a clean-catch midstream specimen

Evacuated transport tubes

Useful for transporting specimens to a referral laboratory

Adulteration

the intentional manipulation of a urine sample. This involves using another person’s or animal’s urine, diluting the sample with water, or adding substances.

Creatinine

Low or zero levels of creatinine indicate diluted or substituted non-human sample.

Nitrites

These are oxidizing substances that react with the drug or drug metabolites. Adding nitrates to the voided urine does not change the color or temperature of the specimen.

pH

pH levels higher than 9.5 or lower than 3 alter the enzymatic rate. Alteration of the pH may also affect the stability of the drug or its metabolite.

Glutaraldehyde

masks the presence of illegal drugs.

Specific gravity

helps to determine presence of adulterants such as table salt. The normal range is 1.005–1.030 (specific gravity of distilled water is 1.000). The specific gravity of urine depends upon fluid intake and the amount of substances dissolved in urine.

Functions of urinalysis

detecting abnormal excretions, intrinsic pathological conditions of the renal system, effectiveness of medications, glucose levels, hormones, ovulation, pregnancy

Urine toxicology

the testing of urine in the clinical laboratory to monitor the use of therapeutic drugs such as antibiotics, anticonvulsants, antidepressants, and barbiturates.

Physical analysis of urine

examining the color, turbidity, volume, foam, odor, and specific gravity of the urine and comparing them against the normal range.

Chemical analysis of urine

the presence of certain chemicals, like glucose, ketones, protein, blood, bilirubin, etc.

Color

Urine is normally yellow in color, ranging from pale straw to yellow to amber. The color of urine depends on the concentration of the pigment urochrome and the amount of water in the specimen.

Turbidity

Urine specimens vary in appearance from clear to very cloudy. Cloudiness in urine is due to cells, bacteria, yeast, vaginal contaminants, or crystals.

Volume

The normal volume of urine production in 24 hours varies according to the age of the person. Infants and children excrete smaller volumes than adults do. The normal volume of urine produced in adults is 750 to 2,000 mL in 24 hours; the average amount is about 1,500 mL.

Foam

Urine does not have foam. The presence of foam in the urine indicates an abnormality. White foam may indicate the presence of increased protein. Greenish-yellow foam indicates bilirubinuria.

Odor

Urine is normally odorless and the presence of odor is an important clue to metabolic disorders. Normal urine is aromatic, and a change in the odor of urine is due to a disease, the presence of bacteria, or diet.

Protein in the urine

Protein in the urine refers to proteinuria, which indicates the first signs of renal disease.

Hematuria

refers to the presence of intact red blood cells in the urine and may be due irritation of the ureter, bladder, or urethra. It indicates cystitis and kidney stones.

Hemoglobinuria

the presence of hemolyzed red blood cells in urine. It indicates intravascular red blood cell destruction and may be due to transfusion reactions, malaria, drug reactions, snakebites, and severe burns.

Myoglobinuria

occurs due to damage of muscle tissue and is common in patients with muscular dystrophy.

Bilirubinuria

an indication of first signs of liver disease or other diseases. Urobilinogen in the urine is an indication of increased red blood cell destruction and of liver disease. Leukocytes (white blood cells) in the urine indicate infections of the urinary tract.

Casts

Casts, which form during protein accumulation and precipitation in the kidney tubules, wash into the urine. Casts are cylindric, with flat or rounded ends, and have classification.

Cells in the urine

• Red blood cells in the urine occur as a result of inflammation or injury.

• Yeast cells in urine indicate vaginal contamination or infection of the urine with yeast.

• White blood cells in large numbers indicate a urinary tract infection or vaginal contamination of the specimen during collection.

Crystals

occur commonly in urine specimens, and their presence does not have any clinical significance unless in large numbers.