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					    156    The Body Systems: Clinical and Applied Topics

    The Urinary System                                           of the urinary bladder, or from CNS damage,
                                                                 such as a stroke or damage to the spinal cord
    The urinary system consists of the kidneys, where            that affects control of the detrusor muscle.
    urine production occurs, and the conducting sys-
                                                             •   Changes in the volume of urine produced indi-
    tem that transports and stores urine prior to its
                                                                 cate that there are problems either at the kid-
    elimination from the body. The conducting system
                                                                 neys or with the control of renal function.
    includes the ureters, the urinary bladder, and the
                                                                 Polyuria, the production of excessive amounts
    urethra. Although the kidneys perform all the vital
                                                                 of urine, may result from hormonal or metabolic
    functions of the urinary system, problems with the
                                                                 problems, such as those associated with dia-
    conducting system can have direct and immediate
                                                                 betes (pp. 90, 92), or damage to the glomeruli,
    effects on renal function.
                                                                 as in glomerulonephritis (p. 158). Oliguria (urine
                                                                 volume 50–500 ml/day) and anuria (0-50
    THE PHYSICAL EXAMINATION                                     ml/day) are conditions that indicate serious kid-
    AND THE URINARY SYSTEM                                       ney problems and potential renal failure. Renal
                                                                 failure can occur with heart failure (p. 115),
    The primary symptoms of urinary system disorders
                                                                 renal ischemia, circulatory shock (p. 113), burns
    are pain and changes in the frequency of urination.
                                                                 (p. 46), and a variety of other disorders.
    The nature and location of the pain can provide
    clues to the source of the problem (see Figure 9-1,          Important clinical signs of urinary system dis-
    EAP p. 279). For example,                                orders include the following:
    •   Pain in the superior pubic region may be asso-       •   Hematuria, the presence of red blood cells in
        ciated with urinary bladder disorders.                   the urine, indicates bleeding at the kidneys or
    •   Pain in the superior lumbar region or the flank          conducting system. Hematuria producing dark
        that radiates to the right upper quadrant or left        red urine usually indicates bleeding in the kid-
        upper quadrant can be caused by kidney infec-            ney, and hematuria producing bright red urine
        tions such as glomerulonephritis, pyelonephri-           indicates bleeding in the lower urinary tract.
        tis, or kidney stones.                                   Hematuria most commonly occurs with trauma
                                                                 to the kidneys, calculi (kidney stones), tumors,
    •   Dysuria (painful or difficult urination) may
                                                                 or urinary tract infections.
        occur with cystitis and urinary obstructions. In
        males, prostatic enlargement can lead to com-        •   Hemoglobinuria is the presence of hemoglobin
        pression of the urethra and dysuria.                     in the urine. Hemoglobinuria indicates
        Individuals with urinary system disorders may            increased hemolysis of red blood cells within
    urinate more or less frequently than usual and may           the circulation, due to cardiovascular or meta-
    produce normal or abnormal amounts of urine:                 bolic problems. Examples of conditions result-
                                                                 ing in hemoglobinuria include the thalassemias
    •   An irritation of the lining of the ureters or uri-       (p. 99), sickle cell anemia (p. 99), hypersplenism
        nary bladder can lead to the desire to urinate           (p. 123), and some autoimmune disorders.
        with increased frequency, although the total
        amount of urine produced each day remains            •   Changes in urine color may accompany some
        normal. Detrusor muscle contractions may also            renal disorders. For example, the urine may
        lead to increased frequency in urination. When           become (1) cloudy, due to the presence of bac-
        these problems exist, the individual feels the           teria, lipids, or epithelial cells; (2) red or brown
        urge to urinate when the urinary bladder vol-            from hemoglobin or myoglobin; (3) blue-green
        ume is very small. The irritation may result from        from bilirubin; or (4) brown-black from exces-
        urinary bladder infection or tumors, increased           sive concentration. Not all color changes are
        acidity of the urine, or detrusor hyper-reflexia.        abnormal, however. Some foods and several
                                                                 prescription drugs can cause changes in urine
    •   Incontinence, an inability to control urination          color. A serving of beets can give urine a red-
        voluntarily, may involve periodic involuntary            dish color, whereas eating rhubarb can give
        urination, or a continual, slow trickle of urine
1       from the urethra. Incontinence may result from
                                                                 urine an orange tint, and B vitamins turn it a
8                                                                vivid yellow.
        urinary bladder or urethral problems, damage
        or weakening of the muscles of the pelvic floor,     •   Renal disorders typically lead to protein loss in
        or interference with normal sensory or motor             the urine (proteinuria) and if severe, results in a
        innervation in the region. Renal function and            generalized edema in peripheral tissues. Facial
        daily urinary volume are normal.                         swelling, especially around the eyes, is often
                                                                 seen.
    •   In urinary retention, renal function is normal,
        at least initially, but urination does not occur.    •   A fever commonly develops when the urinary
        Urinary retention in males often results from            system is infected by pathogens. Urinary blad-
        prostatic enlargement and compression of the             der infections (cystitis) often result in a low-
        prostatic urethra. In both sexes, urinary reten-         grade fever; kidney infections, such as
        tion may result from obstruction of the outlet           pyelonephritis, usually produce very high fevers.
                                                                                    The Urinary System      157

    During the physical assessment, palpation can                Many procedures and laboratory tests are used
be used to check the status of the kidneys and uri-          in the diagnosis of urinary system disorders. The
nary bladder. The kidneys lie in the costovertebral          functional anatomy of the urinary system can be
area, the region bounded by the lumbar spine and             examined by using a variety of sophisticated proce-
the 12th rib on either side. To detect tenderness            dures. For example, administering a radiopaque
due to kidney inflammation, the examiner gently              compound that will enter the urine permits the cre-
taps over the costovertebral area with a fist. This                                                  ¯
                                                             ation of an intravenous pyelogram (PI-el-|-gram),
usually does not cause pain unless the underlying            or IVP, by taking an X-ray of the kidneys. This pro-
kidney is inflamed.                                          cedure permits detection of unusual kidney, ureter,
    The urinary bladder can be palpated just supe-           or bladder structures and masses. Computerized
rior to the pubic symphysis. However, on the basis           tomography (CT) scans and ultrasounds also pro-
of palpation alone, urinary bladder enlargement              vide useful information concerning abnormalities.
can be difficult to distinguish from the presence of         Figure A-53 is a simple concept map outlining the
an abdominal mass.                                           major classes of disorders of the urinary system.



                                                                                     Figure A-53 Disorders of the
                                           Inflammation and infection                Urinary System

                                           Urinary tract infections (UTIs)
                                           Kidney
                                            Nephritis
                                            Pyelitis
                                            Pyelonephritis
                                            Leptospirosis
                                           Ureter
                                            Ureteritis
                                           Urinary bladder
                                            Cystitis
                                           Urethra
                                            Urethritis



          Congenital disorders                                                              Tumors

                                                                                 Kidney
     Polycystic kidney disease                                                    Renal cell carcinoma
     Tubular function disorders                                                   Nephroblastoma
      Renal glycosuria                                                           Urinary bladder
      Aminoaciduria                                                               Bladder cancer
       Cystinuria
                                             URINARY SYSTEM
                                               DISORDERS
        Degenerative disorders

     Incontinence
     Renal failure                                                                     Immune disorders
      Acute renal failure
      Chronic renal failure                                                      Glomerulonephritis


                                           Disorders of renal function

                                           Fluid imbalances                                                         1
                                            Edema
                                           Electrolyte imbalances
                                                                                                                    8
                                            Hypernatremia
                                            Hyponatremia
                                            Hyperkalemia
                                            Hypokalemia
                                            Hypercalcemia
                                            Hypocalcemia
                                           Acid–base imbalances
                                            Respiratory acidosis
                                            Respiratory alkalosis
                                            Metabolic acidosis
                                            Metabolic alkalosis
    158     The Body Systems: Clinical and Applied Topics

          Conditions Affecting                                     Glomerulonephritis                   EAP p. 556
          Filtration                           EAP p. 555                                               ¯
                                                              Glomerulonephritis (glo-mer-≈-l|-nef-RI-tis) is an
    Changes in filtration pressure can result in signifi-     inflammation of the renal cortex that affects the fil-
    cant alterations in kidney function. Factors that         tration mechanism. This condition, which may
    can disrupt normal filtration rates include physical      develop after an infection by Streptococcus bacteria,
    damage to the filtration apparatus and interference       is an example of an immune complex disorder. The
    with normal filtrate or urine flow.                       primary infection may not occur in or near the kid-
    PHYSICAL DAMAGE TO THE FILTRATION                         neys. However, as the immune system responds to
    APPARATUS                                                 the infection, the number of circulating antigen-
                                                              antibody complexes skyrockets. These complexes
    The glomerular filtration membrane can be injured         are small enough to pass through the basement
    by mechanical trauma, such as a blow to the kid-          membrane but too large to fit between the slit
    neys, by bacterial infection, by circulating immune       pores. As a result, the filtration mechanism clogs
    complexes, or by exposure to metabolic poisons,           up and filtrate production declines. Any condition
    such as mercury. The usual result is a sudden             that leads to a massive immune response can
    increase in the permeability of the glomerulus.           cause glomerulonephritis, including viral infections
    When damage is severe, plasma proteins and even           and autoimmune disorders.
    blood cells enter the capsular spaces. The loss of
    plasma proteins has two immediate effects: (1) it              Diuretics                            EAP p. 558
    reduces the osmotic pressure of the blood, and (2) it
    increases the osmotic pressure of the filtrate. The       Diuretics (dª-≈-RET-iks) are drugs that promote
    result is an increase in the net filtration pressure      the loss of water in the urine. Diuretics have many
    and an increased rate of filtrate production.             different mechanisms of action, but each affects
        Blood cells entering the filtrate will not be reab-   transport activities or water reabsorption along the
    sorbed. The presence of blood cells in the urine is       nephron and collecting system. Important diuretics
    called hematuria (hƒm-a-TOOR-ƒ-uh). Although              in use today include
    small amounts of protein can be reabsorbed, when
    glomeruli are severely damaged, the nephrons are          •   Osmotic diuretics: Osmotic diuretics are meta-
    unable to reabsorb all the plasma proteins entering           bolically harmless substances that are filtered
    the filtrate. Plasma proteins then appear in the              at the glomerulus and ignored by the tubular
    urine, a condition termed proteinuria (pr|-tƒn-               epithelium. Their presence in the urine
    OOR-ƒ-uh). Proteinuria and hematuria indicate                 increases its osmolarity and limits the amount
    that kidney damage has occurred.                              of water reabsorption possible. Mannitol (MAN-
                                                                  i-tol) is the most frequently administered
    INTERFERENCE WITH FILTRATE OR URINE                           osmotic diuretic. It is used to accelerate fluid
    FLOW                                                          loss and speed the removal of toxins from the
    If the tubule, collecting duct, or ureter becomes             blood and to elevate the GFR after severe trau-
    blocked and urine flow cannot occur, capsular                 ma or other conditions have impaired renal
    pressures gradually rise. When the capsular hydro-            function.
    static pressure and blood osmotic pressure equal          •   Drugs that block sodium and chloride transport:
    the glomerular hydrostatic pressure, filtration                                                       ¯
                                                                  A class of drugs called thiazides (THI-a-zªdz)
    stops completely. The severity of the problem                 reduce sodium and chloride transport in the
    depends on the site of the blockage. If it involves a         proximal and distal tubules. Thiazides such as
    single nephron, only a single glomerulus will be              chlorothiazide are often used to accelerate fluid
    affected. If the blockage occurs within the ureter,           losses in the treatment of hypertension and
    filtration in that kidney will come to a halt. If the         peripheral edema.
    blockage occurs in the urethra, both kidneys will
    become nonfunctional. Examples of factors                 •   High-ceiling, or loop, diuretics: The high-ceiling
    involved in urinary blockage are discussed later              diuretics, such as furosemide and bumetanide,
                                                                  inhibit transport along the loop of Henle,
1   (see Problems with the Conducting System.)
                                                                  reducing the osmotic gradient and the ability to
8        Elevated capsular pressures can also result
    from inflammation of the kidneys, a condition                 concentrate the urine. They are called high-
                            ¯
    called nephritis (nef-RI-tis). A generalized nephritis        ceiling diuretics because they produce a much
    may result from bacterial infections or exposure to           higher degree of diuresis than other drugs.
    toxic or irritating drugs. One of the major problems          They are fast-acting and are often used in a
    in nephritis is that the inflammation causes                  clinical crisis—for example, in treating acute
    swelling, but the renal capsule prevents an                   pulmonary edema. In both the thiazide and the
    increase in the size of the kidney. The result is an          furosemide diuretics, water, Na+, and K+ are
    increase in the hydrostatic pressures in the per-             lost in the urine.
    itubular fluid and filtrate. This pressure opposes        •   Aldosterone blocking agents: Blocking the
    the glomerular hydrostatic pressure, lowering the             action of aldosterone prevents the reabsorption
    net filtration pressure and the GFR.                          of sodium along the DCT and collecting tubule,
                                                                                           The Urinary System   159

    and so accelerates fluid losses. The drug                     familiar drugs, caffeine and alcohol, have pro-
    spironolactone is this type of diuretic. It is often          nounced diuretic effects. Caffeine produces
    used in conjunction with other diuretics                      diuresis directly, by reducing sodium reabsorp-
    because blocking the aldosterone-activated                    tion along the tubules. Alcohol works indirect-
    exchange pumps helps reduce the potassium                     ly, by suppressing the release of ADH at the
    ion loss. These drugs are also known as potas-                posterior pituitary gland.
    sium-sparing diuretics. Atrial natriuretic pep-
    tide may be used as a diuretic because it                       Urinalysis                            EAP p. 558
    counteracts the effects of both aldosterone and
                                                              Several basic screening tests can be performed by
    ADH at the kidneys.
                                                              recording changes in the color of test strips that
•   ACE inhibitors: ACE inhibitors (angiotensin               are dipped in the sample. Urine pH and urinary
    converting enzyme inhibitors) prevent the for-            concentrations of glucose, ketones, bilirubin, uro-
    mation of angiotensin II by its converting                bilinogen, plasma proteins, and hemoglobin can be
    enzyme. This prevents stimulation of aldos-               monitored using this technique. In addition, the
    terone production and promotes water loss.                density or specific gravity of the urine is usually
•   Drugs with diuretic side effects: Many drugs              determined, using a simple device known as a uri-
    prescribed for other conditions promote diure-            nometer (≈-ri-NOM-e-ter) or densitometer (den-si-
    sis as a side effect. For example, drugs that             TOM-e-ter). The sample may also be spun in a
    block carbonic anhydrase activity, such as                centrifuge and any sediment examined under the
    acetazolamide (Diamox), have an indirect effect           microscope. Mineral crystals, bacteria, red or white
    on sodium transport. Although they cause                  blood cells, and deposits, known collectively as
    diuresis, these drugs are seldom prescribed               casts, can be detected in this way. Figure A-54
    with that in mind. (Because carbonic anhy-                provides an overview of the major categories of uri-
    drase is also involved in aqueous humor secre-            nary casts. During a urinary tract infection, bacte-
    tion, Diamox is used to reduce intraocular                ria may be cultured to determine their specific
    pressure in glaucoma patients.) Two more                  identities.




                                                                                                                       1
                                                                                                                       8




Figure A-54   Microscopic examination of urine sediment (redrawn after Todd and Sanford)
    160    The Body Systems: Clinical and Applied Topics

         More comprehensive analyses can determine              The composition of dialysis fluid is indicated in
    the total osmolarity of the urine and the concentra-    Table A-24. As diffusion takes place across the
    tion of individual electrolytes and minor metabo-       membrane, the composition of the blood changes.
    lites, metabolic wastes, vitamins, and hormones. A      Potassium ions, phosphate ions, sulfate ions, urea,
    test for one hormone in the urine, human chorionic      creatinine, and uric acid diffuse across the mem-
    gonadotrophin (hCG), provides an early and reliable     brane into the dialyzing fluid. Bicarbonate ions and
    indication of pregnancy.                                glucose diffuse into the bloodstream. In effect, dif-
         The information provided by urinalysis can be      fusion across the dialysis membrane takes the
    especially useful when correlated with the data         place of normal glomerular filtration, and the char-
    obtained from blood tests. The term azotemia (a-        acteristics of the dialysis fluid ensure that impor-
    z|-T¬-mƒ-uh) refers to the presence of excess           tant metabolites remain in the circulation rather
    metabolic wastes in the blood. This condition may       than diffusing across the membrane.
    result from overproduction of urea or other nitroge-        In practice, silastic tubes, called shunts, are
    nous wastes by the liver (“pre-renal syndrome”). In     inserted into a medium-sized artery and vein. (The
    uremia (≈-R¬-mƒ-uh), by contrast, all normal kid-       usual location is in the forearm, although the lower
    ney functions are adversely affected. The symptoms      leg is sometimes used.) The two shunts are then
    of uremia, which are those of kidney failure,           connected as shown in Figure A-55b. The connec-
    include hypertension, anemia (because of a decline      tion acts like a “short circuit” that does not impede
    in the production of erythropoietin), and central       blood flow, and the shunts can be used like taps in
    nervous system problems that may lead to sleep-         a wine barrel, to draw a blood sample or to connect
    lessness, seizures, delirium, and even coma.            the individual to a dialysis machine. When con-
         The total volume of urine produced in a 24-        nected to the dialysis machine, the individual sits
    hour period may also be of interest. Polyuria (pol-     quietly while blood circulates from the arterial
    ƒ-◊-rƒ-uh) refers to excessive production of urine,     shunt, through the machine, and back via the
    well over 2 liters per day. Polyuria most often         venous shunt. Inside the machine, the patient’s
    results from endocrine disorders, such as the vari-     blood flows across a dialyzing membrane, where
    ous forms of diabetes, metabolic disorders, or          diffusion occurs. For long term dialysis, a surgical-
    damage to the filtration apparatus, as in glomeru-      ly created arteriovenous anastomosis in the arm or
    lonephritis. Oliguria (o-li-G◊-rƒ-uh) refers to inad-   leg provides easier access.
    equate urine production (50–500 ml/day). In                 Use of a dialysis machine is suggested when
    anuria (a-N◊-rƒ-uh), a negligible amount of urine       a patient’s BUN (blood urea nitrogen) exceeds 100
    is produced (0–50 ml/day), and a potentially fatal      mg/dl (the normal value is 30 mg/dl). Dialysis
    problem exists.                                         techniques are useful because they can maintain
                                                            patients awaiting a transplant or those whose
          Advances in the Treatment of                      kidney function has been temporarily disrupted.
                                                            Hemodialysis does have a number of drawbacks,
          Kidney Failure          EAP p. 560
                                                            however: (1) the patient must sit by the machine
    Many conditions can result in kidney failure, or
    renal failure. Management of chronic renal failure      TABLE A-24           The Composition of Dialysis Fluid
    typically involves restricting water and salt intake
    and reducing protein intake to a minimum, with                                                                    Dialyzing
    few dietary proteins. This combination reduces           Constituent                         Plasma               Fluid
    strain on the urinary system by (1) minimizing the
    volume of urine produced and (2) preventing the          ELECTROLYTES (mEq/l)
    generation of large quantities of nitrogenous            Potassium                                4                     3
    wastes. Acidosis, a common problem in patients           Bicarbonate                             27                    36
    with renal failure, can be countered by the inges-       Phosphate                                3                     0
    tion of bicarbonate ions.                                Sulfate                                  0.5                   0
         If drugs and dietary controls cannot stabilize      NUTRIENTS (mg/dl)
    the composition of the blood, more drastic mea-
1   sures are taken. In hemodialysis (hƒ-m|-dª-AL-i-
                                                              Glucose                          80-100                    125
8   sis), an artificial membrane is used to regulate the
                                                             NITROGENOUS
                                                             WASTES (mg/dl)
    composition of the blood by means of a dialysis
                                                             Urea                                    20                      0
    machine (Figure A-55a). The basic principle
                                                             Creatinine                               1                      0
    involved in this process, called dialysis, involves
                                                             Uric acid                                3                      0
    passive diffusion across a selectively permeable
    membrane. The patient’s blood flows past an artifi-     Note: Only the significant variations are noted; values for other electrolytes
    cial dialysis membrane that contains pores large        are usually similar. Although these values are representative, the precise
    enough to permit the diffusion of small ions but        composition can be tailored to meet the specific clinical needs. For example,
                                                            if plasma potassium levels are too low, the dialyzing fluid concentration can
    small enough to prevent the loss of plasma pro-         be elevated to remedy the situation. Changes in the osmolarity of the dialyz-
    teins. On the other side of the membrane flows a        ing fluid can also be used to adjust an individual’s blood volume, usually by
    special dialysis fluid.                                 adjusting the glucose content of the dialyzing fluid.
                                                                                                   The Urinary System           161




                                                                                                   Thermometer
                                                                   Dialysis                Blood
                                                                   chamber                 pump

                                                                                                         Dialysis
                                                                                                         solution




                                                                                                                      Holding
                                                                                                                       tank


                                                                   To
                                                                  drain




                                                                                             Flowmeter


    (a)
                           Artery                                   Air detector
                                              Shunt                 and clamp




                          Vein



                                                                                     (b)


FIGURE A-55     Hemodialysis
(a) A patient connected to a dialysis machine. (b) A diagrammatic view of the dialysis procedure. Preparation for hemodialysis typi-
cally involves implantation of a pair of shunts connected by a loop that permits normal blood flow when the patient is not hooked
up to the dialysis machine.



about 15 hours per week; (2) between treatments,                     fluid through the catheter and then continues with
the symptoms of uremia will gradually develop;                       life as usual until 4 to 6 hours later, when the fluid
(3) hypotension can develop as a result of fluid                     is removed and replaced.
loss during dialysis; (4) air bubbles in the tubing                       Probably the most satisfactory solution, in
can cause embolism formation in the blood-                           terms of overall quality of life, is kidney transplan-
stream; (5) anemia often develops; and (6) the                       tation. This procedure involves the implantation of
shunts can serve as sites of recurring infections.                   a new kidney obtained from a living donor or from
    One alternative to the use of a dialysis machine                 a cadaver. One-third of the estimated 14,000 kid-
is peritoneal dialysis, in which the peritoneal lin-                 neys transplanted in 1999 were obtained from liv-                 1
ing is used as a dialysis membrane. Dialyzing fluid                  ing, related donors. In most cases, the damaged                   8
is introduced into the peritoneum through a                          kidney is usually removed, and its blood supply is
catheter in the abdominal wall, and at intervals the                 connected to the transplant. When the original kid-
fluid is removed and replaced. One procedure                         ney is left in place, an arterial graft is inserted to
involves cycling 2 liters of fluid in an hour—15                     carry blood from the iliac artery or the aorta to the
minutes for infusion, 30 minutes for exchange, and                   transplant, which is placed in the pelvis or lower
15 minutes for fluid reclamation. This process is                    abdomen.
usually performed overnight while the patient                             The success rate for this procedure varies,
sleeps. In an interesting variation of this procedure                depending on how aggressively the recipient’s T
called continuous ambulatory peritoneal dialysis                     cells attack the donated organ and whether or not
(CAPD), the patient administers 2 liters of dialyzing                an infection develops. The 1-year success rate for
162    The Body Systems: Clinical and Applied Topics

implantation is now 85 to 95 percent. The use of
kidneys taken from close relatives significantly
                                                              Urinary Tract Infections               EAP p. 563
improves the chances for a successful transplant.        Urinary tract infections, or UTIs, result from the
Immunosuppressive drugs are administered to              colonization of the urinary tract by bacterial or fungal
reduce tissue rejection, but unfortunately, this         invaders. The intestinal bacterium Escherichia coli is
treatment also lowers the individual’s resistance to     most often involved, and women are particularly sus-
infection.                                               ceptible to urinary tract infections because of the
                                                         proximity of the external urethral orifice to the anus.
      Problems with the Conducting                       Sexual intercourse may also push bacteria into the
      System                  EAP p. 562                 urethra, and since the female urethra is relatively
                                                         short, the urinary bladder may become infected.
Local blockages of the collecting tubules, collecting         The condition may be asymptomatic (without
ducts, or ureter may result from the formation of        symptoms), but it can be detected by the presence
casts, small blood clots, epithelial cells, lipids, or   of bacteria and blood cells in the urine. If inflam-
other materials. Casts are often excreted in the         mation of the urethral wall occurs, the condition
urine and visible in microscopic analysis of urine       may be termed urethritis, while inflammation of the
samples. Calculi (KAL-k≈-lª), or “kidney stones,”        lining of the bladder is called cystitis. Many infec-
form from calcium deposits, magnesium salts, or          tions, including sexually transmitted diseases such
crystals of uric acid. This condition is called          as gonorrhea, cause a combination of urethritis
                             ¯
nephrolithiasis (nef-r|-li-THI-a-sis). The blockage of   and cystitis. These conditions cause painful urina-
the urinary passage by a stone or other factors,         tion, a symptom known as dysuria (dis-◊-rƒ-uh),
such as external compression, results in urinary         and the bladder becomes tender and sensitive to
obstruction. Urinary obstruction is a serious prob-      pressure. Despite the discomfort produced, the
lem because, in addition to causing pain, it will        individual feels the urge to urinate frequently.
reduce or eliminate filtration in the affected kidney    Urinary tract infections usually respond to antibi-
by elevating the capsular hydrostatic pressure.          otic therapies, although subsequent reinfections
    Kidney stones are usually visible on an X-ray,       may occur.
and if peristalsis and fluid pressures are insuffi-           In untreated cases the bacteria may proceed
cient to dislodge them, they must be surgically          along the ureters to the renal pelvis. The resulting
removed or destroyed. One interesting nonsurgical        inflammation of the walls of the renal pelvis pro-
procedure involves breaking kidney stones apart                                   ¯
                                                         duces pyelitis (pª-e-LI -tis), and if the bacteria
with a lithotripter, the same apparatus used to          invade the renal cortex and medulla as well,
destroy gallstones. Another nonsurgical approach                                       ¯
                                                         pyelonephritis (pª-e-l|-nef-RI-tis) results. Signs and
entails the insertion of a catheter armed with a         symptoms include a high fever, intense pain on the
laser that can shatter kidney stones with intense        affected side, vomiting, diarrhea, and the presence
light beams.                                             of blood cells and pus in the urine.




CRITICAL-THINKING QUESTIONS                                  Specific gravity: 1.030
                                                             RBCs: numerous RBCs per high-power field
    10-1. Martha’s first patient on the pediatric
floor is a 12-year-old boy named Sam who is                  Protein: >1 g/24 hr
undergoing kidney dialysis treatments. Sam has               Casts: epithelial cells and RBCs
been on dialysis for the last week, and the treat-
ments will probably be discontinued because his              Other Values:
kidneys are becoming fully functional again.                 BUN: 90 mg/dl
Martha questions Sam’s mother concerning his ill-
                                                             Creatinine: 4 mg/dl
ness. Three weeks earlier, Sam had a sore throat
that kept him home from school for two days but              Creatine clearance test: 50 ml/min
was not medically treated. One week earlier, Sam
told his mother his urine looked red-brown and           What is a possible diagnosis?
foamy. He was admitted to the hospital. Physical
examination revealed costovertebral tenderness               a. glomerulonephritis
and blood pressure of 135/90. The urinalysis and             b. cystitis
other studies revealed the following:
                                                             c.   urinary obstruction
Urinalysis                                                   d. pyelitis
   Color: red-brown tinged                                   e.   none of the above
                                                                             The Urinary System     163

    10-2. Fred suffers from chronic emphysema.            10-4. A young college student is struck by a
His arterial blood gas results are as follows:        car. On arriving at the ER, she is unconscious with
                                                      internal hemorrhaging. How will this affect her
   pH: 7.30                                           GFR? Why?
   bicarbonate: 32 mEq/l                                  10-5. Koji collapses in the final leg of a
   PCO2: 50 mm Hg                                     marathon and is rushed to a hospital with acute
                                                      renal dysfunction. A blood test shows elevated
Which of the following disorders best describes       serum potassium levels, lowered serum sodium
Fred’s condition?                                     levels, and a decrease in the GFR. How are these
                                                      symptoms related to the marathon?
   a. metabolic acidosis with respiratory
      compensation                                        10-6. Lucy, 10 years old, experiences a signifi-
   b. respiratory acidosis with metabolic             cant weight gain over 12 days. Her abdomen is dis-
      compensation                                    tended, and her limbs are swollen. She complains
   c. metabolic alkalosis with respiratory            of abdominal discomfort and general achiness. Her
      compensation                                    parents take her to a physician. Lucy recently had
   d. respiratory alkalosis with metabolic            a bad sore throat, but it soon cleared up.
      compensation                                    Urinalysis indicates proteinuria and hematuria. A
                                                      blood test indicates the presence of antibodies to
    10-3. Peter, a 50-year-old banker, finds he has
                                                      toxins produced by Streptococcus bacteria. What
high blood pressure (150/110) when his nursing
                                                      may be the cause of Lucy’s problems?
student daughter is practicing her skills on him.
Peter’s physician confirms her findings and begins        10-7. Mr Smith, 68 years old, suffers from type
some laboratory and diagnostic tests to determine     2 diabetes mellitus (NIDDM). One afternoon he
the cause. Routine lab work was within normal         complains of abdominal pain and fatigue. He then
limits. Adrenal gland function is normal. Because a   becomes unconscious, and he is comatose on
prominent bruit was heard over the right upper        arrival at the hospital. Make predictions about his
abdomen during the physical exam, renal angiog-       blood pH, urine pH, plasma P CO , and plasma
                                                                                          2
raphy was ordered. The renal angiogram revealed a     potassium levels.
narrowing of the right renal artery. How is this
related to the hypertension?




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