Chapter 10 Diseases and Disorders of the Urinary System Learning Objectives After studying this chapter, you should be able to L Describe the anatomy and the functions of kidneys, nephrons, ureters, urinary bladder, and urethra L Identify the etiology, signs and symptoms, diagnostic tests, and treatment for acute kidney injury and other acute and inflammatory diseases of the urinary system L Know the etiology, and describe the signs and symptoms, diagnostic tests, and treatment of urinary tract infections L Identify the etiology, signs and symptoms, diagnostic tests, and treatment for chronic kidney disease, hypertensive kidney disease, diabetic nephropathy, nephrotic syndrome, end-stage renal disease, and other chronic diseases of the urinary system L Describe kidney dialysis L Recognize the etiology, signs and symptoms, and modes of treat- Histopathology of kidney showing ment for renal cell carcinoma, Wilm’s tumor, and bladder cancer nodular glomerulosclerosis characteristic of diabetes mellitus. (Courtesy of L Describe common congenital disorders of the urinary system the Centers for Disease Control and Prevention/Dr. Edwin P. Wing, Jr., 1974) L Describe common age-related diseases of the urinary system Fact or Fiction? Kidney stones occur only in the kidneys. Fiction: Kidney stones may form anywhere within the urinary system, but they usually form in the renal pelvis or calyces of the kidney and they can lodge in the ureters. 198 M10_ZELM4744_08_SE_C10.indd 198 04/04/14 3:20 PM Disease Chronicle What’s in a Name? Many anatomical structures once bore the names of the scientists who first discovered them. Recently anatomists have revised anatomical nomenclature and we no longer formally name organs after scientists. Instead, we apply descriptive anatomical terminology to structures. The glomerulus or renal corpuscle was formerly known as the malpighian corpuscle, named for Italian anatomist Marcello Malpighi (1628–1694) who first published a description of the glomerulus. One of the micro- scopic filtration tubules now called the renal loop was for many years named the loop of Henle, for Friedrich Gustav Jakob Henle, who described it in 1862. 199 M10_ZELM4744_08_SE_C10.indd 199 04/04/14 3:21 PM 200 L Part II Diseases and Disorders of the Systems Anatomy and Physiology Review where blood is filtered into the surrounding glomerular capsule. This filtrate contains fluid The organs of the urinary system filter the blood, from plasma and some of its constituents. As form and store urine, and excrete urine from the the filtrate continues on through the proxi- body. The urinary system is comprised of two mal renal tubule, renal loop, and distal renal kidneys and ureters, a urinary bladder, and a tubule, its composition is altered. Much water urethra. The two kidneys are retroperitoneal, is retained (reabsorbed into nearby capillaries), located behind the peritoneum of the posterior as are glucose and electrolytes. Acid and urea abdominopelvic cavity. Leading from each kidney are not reabsorbed. Instead, these are excreted is a ureter that drains urine to the urinary blad- and move with the filtrate to the collecting ducts, der, located on the floor of the pelvic cavity. The forming urine. Normal urine does not contain urethra drains urine from the urinary bladder blood cells, plasma proteins, or glucose. to the outside. Urine from the collecting ducts of the neph- The kidneys are critical for homeostasis. rons eventually empties into the renal calyces Kidneys continually remove waste and toxins and renal pelvis at the junction of the kidneys from the blood, regulate water and electro- with the ureters, and moves down the ureters to lyte levels, and control pH and blood pressure. the urinary bladder. Neural signals governing Kidneys also produce renin, which regulates micturition stimulate the bladder to empty urine blood pressure, and erythropoietin, which stimu- into the urethra, which leads outside the body. lates red blood cell production. Kidneys produce Figure 10–2 illustrates the urinary system. approximately 1 milliliter of urine per minute. In doing so, 20–25% of the body’s blood volume flows within the kidneys at any given time. Diagnostic Tests and Procedures The Nephron History and Physical Exam The functional unit of the kidney is the nephron. Diagnosis of urinary system diseases requires Approximately a million nephrons reside within assessing patient history. Important factors each kidney. As blood passes through the neph- include the presence of other diseases, especially rons, metabolic waste products are filtered from diabetes, hypertension, and urinary tract infec- the blood plasma. At the same time, most of the tions. A history should also determine exposure water (99%) is reabsorbed, along with nutrients to medicines, antibiotics, and kidney toxins or such as glucose and amino acids. Extra water, abuse of analgesics such as acetaminophen. excess ions, acid, some drugs, and metabolic Diagnostic information can be gathered from wastes such as urea and creatinine are excreted. patient reports about fever, pain, and urine vol- The hormones aldosterone and antidiuretic ume, frequency, or color. Family history of renal hormone (ADH) play important roles in the regu- diseases can indicate a genetic predisposition for lation of the nephron’s ability to reabsorb salt certain diseases. and water. A physical exam can reveal renal disease Each nephron consists of an afferent arte- because the entire body is affected. For example, riole, an efferent arteriole, a glomerulus, a glo- edema can be detected in skin, around the eyes, merular capsule, a proximal convoluted tubule, and on the ankles. As toxins accumulate in the a renal loop (loop of Henle), and a distal con- blood, neurologic abnormalities arise, including voluted tubule that leads to a collecting duct. disorientation and changes in consciousness The components of the nephron are shown in and response to stimuli. Changes in electrolyte Figure 10–1 . levels occur with renal disease, causing hyper- The afferent arteriole carries blood into the tension and a strong, irregular pulse. Alterations nephron and enters the glomerulus, a network in pH levels result in acidosis, which triggers of specialized selectively permeable capillaries, hyperventilation. M10_ZELM4744_08_SE_C10.indd 200 04/04/14 3:21 PM Chapter Ten Diseases and Disorders of the Urinary System L 201 Glomerular capsule Efferent arteriole Afferent arteriole Glomerulus Proximal tubule Distal tubule Vein Collecting tubule Loop of Henle Pyramid in renal medulla Renal capsule Hilum of kidney Renal cortex Renal artery Renal Renal pelvis vein Ureter Calyx Figure 10–1 The kidney with an expanded view of the nephron. M10_ZELM4744_08_SE_C10.indd 201 04/04/14 3:21 PM 202 L Part II Diseases and Disorders of the Systems Kidney Produces urine and helps regulate body fluids Ureter Transports urine to the bladder Urinary bladder Serves as a reservoir for urine Urethra Conveys urine to exterior Figure 10–2 The urinary system. Urinalysis and Laboratory Tests Urine is centrifuged and examined microscop- Renal disease can be detected through analy- ically for red blood cells, white blood cells, bacte- sis of blood for creatinine, uric acid, and blood ria, crystals, and casts. Casts form within kidney urea nitrogen. Significant diagnostic information tubules from which the casts take their cylindri- can be obtained by urinalysis, in which a urine cal forms. Casts consist of coagulated protein, specimen is studied physically, chemically, and blood cells, and epithelial cells. microscopically. Physical factors include urine color, clarity, odor, pH, and specific gravity. The Imaging Techniques color of normal urine ranges from pale yellow to amber. Ultrasound and CT allow visualization of the The color and volume of urine may indicate kidneys, ureters, and bladder. A cystoscopic disease. For example, diabetics produce large examination enables visualization of the inside volumes of pale and dilute urine. In chronic of the bladder and urethra. The cystoscope is kidney diseases, the ability of the renal tubules a long, lighted instrument resembling a narrow to concentrate urine is absent. As a result, the hollow tube inserted through the urethra into urine is dilute and pale, and the specific gravity the bladder. is low. The presence of red blood cells imparts a reddish-brown color to urine. Chemical tests may employ a urine dipstick Acute Diseases and Disorders to detect a variety of chemicals. For example, albumin in the urine (albuminuria) can indicate Acute Kidney Injury inflammation of the urinary tract, particularly Acute kidney injury is the sudden onset of of the glomeruli. The presence of glucose in the impaired renal function. Acute kidney injury urine is one of the signs of diabetes mellitus. has three main causes. One is shock, which M10_ZELM4744_08_SE_C10.indd 202 04/04/14 3:21 PM Chapter Ten Diseases and Disorders of the Urinary System L 203 interrupts blood flow to the kidneys. Second is during catheterization, or following poor hygiene. tubular necrosis, which results in a number of Because females have a shorter urethra, the diseases such as systemic lupus erythemato- prevalence of UTIs is greater in females than in sus, sickle cell disease, renal vein thrombosis, males. acute poststreptococcal glomerulonephritis, or exposure to toxins. Third is obstructed urine Lower UTIs: Urethritis and Cystitis Urethritis flow, a condition arising with kidney stones, an and cystitis are fairly common UTIs. Urethritis