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Urinary System Disorders
Bio 375
Pathophysiology
Incontinence
Incontinence or loss of voluntary controlof the bladder has many causes:
Stress incontinence can occur with:
Coughing
Laughing
Women whose urogenital diaphragm hasweakened from several pregnancies
Age
Spinal cord injuries can interfere withvoluntary neurologic control of the bladder
Retention
Retention is inability to empty bladder
Micturition reflex is located in the sacral
spinal cord and can be blocked by spinalcord injuries
Retention may be caused by anesthesia,either general or spinal
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Urinalysis
Constituents may vary with diet anddrugs
Urine is usually clear and straw-coloredwith a mild odor
pH usually 4.5-8.0
Volume 1.0-1.5 liters/day but varieswith intake, sweating, etc
Abnormalities in Urine
Cloudy- may indicate the presence oflarge amounts of protein, blood cells,bacteria or pus
Dark color- may indicate blood,excessive bilirubin content, or highlyconcentrated urine
Unpleasant or unusual odor- may
indicate infection
Abnormal Constituents
Blood (hematuria)
Small amounts associated with infection,
inflammation or tumors of urinary tract Large amounts of red blood cells indicate
increased glomerular permeability or hemorrhagein the tract
Protein (proteinuria, albuminuria)- indicatesthe leakage of albumin or mixed plasmaproteins into the filtrate indicatinginflammation or increased permeability ofglomeruli
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Bacteria (bacteriuria) or pus (pyuria)-indicate infection in the urinary tract
Urinary casts- may indicateinflammation of the kidney tubules
Specific gravity- indicates the ability ofthe tubules to concentrate the urine; avery low gravity (dilute urine) usuallyrelated to renal failure
Dialysis
Dialysis provides an “artificial kidney” which can be used to sustain life afterkidneys fail.
Dialysis is used to treat someone whohas acute renal failure (can functionnormally on half of one kidney)
Two forms of dialysis:
Hemodialysis- in hospital or dialysis center Peritoneal dialysis- can be done at home
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Hemodialysis required 3-4 timesper week for 3-4 hour sessions
Anticoagulant required to preventclotting
Peritoneal dialysis may be doneat night while patient sleeps
Takes more time than hemodialysis
Continuous ambulatory peritonealdialysis (CAPD)
Urinary Tract Infections Very common
Urine excellent medium for growth ofmicroorganisms Cystitis and urethritis are considered lower urinary
tract infections
Pyelonephritis is an upper urinary tract infection
Most infections are ascending from outside ofbody traveling up the mucous membrane tobladder and then up the ureters to thekidney, often caused by E. coli
Occasionally, pyelonephritis results fromblood-borne infection
Etiology of Urinary Infections
Women are anatomically morevulnerable to urinary tract infections
than men because of: Shortness and width of urethra
Proximity of urethra to anus
Frequent irritation to the tissues fromtampons, bubble bath, deodorants andsexual activity
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Older men with prostatic hypertrophyand retention of urine frequentlydevelop infection
Because of the shared structures withthe reproductive system, any infectionof the reproductive organs is likely toextend to the urinary tract
Common Causative Factors inMen and Women
Bladder retention of urine
Any obstruction of urine flow
All these conditions tend to result inincomplete flushing of bacteria from thebladder and urethra by voiding
Congenital abnormalities in children area common cause of UTI
Pregnancy
Scar tissue
Renal calculi
Vesicoureteral reflux all contribute toinfection because the urine and anycontaminants do no flow freely throughand out of the system
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Infection may result from decreased hostresistance from immunosuppression
Impaired blood supply to the bladderfrom aging
Diabetes mellitus (vascular impairmentand glycosuria)
Catheters or instruments introduced intothe bladder may introduce bacteria intothe bladder or traumatize bladder wall
SeveralSources ofUTI
Inflammatory Disorders
Glomerulonephritis may have severalcauses
Acute poststreptococcalglomerulonephritis is one example
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It typically follows streptococcal infectionwith certain types of group A beta-hemolytic Streptococcus
Usually begins as upper respiratoryinfection, middle ear infection, skin infectionor “strep throat”
The glomerulonephritis develops about 7-10days after the original infection
Primarily affects children between 3-7especially boys
Pathophysiology of APSGN
Antistreptococcal antibodies formedfrom the earlier infection, create anantigen-antibody complex that
lodges in the glomerular capillaries
Activates complement
Causes an inflammatory response in bothkidneys
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In most cases, recovery takes placewith minimal residual damage
Some cases, particularly in adults, arenot easily resolved:
Acute renal failure occurs in about 2% ofcases
Chronic glomerulonephritis persists inabout 10% of cases which graduallydestroys the kidneys
Urinary Tract Obstructions
In older men, benign prostatichypertrophy or prostatic cancerfrequently obstructs the urinary tract
Renal calculi (kidney stones) are acommon cause of obstruction in bothmen and women
Kidney Stones
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Urolithiasis (Calculi or KidneyStones)
Calculi may develop anywhere in theurinary tract
Stones may be small or very large (e.g.staghorn calculus)
Any solid material may act as a nidusaround which other material mayaccumulate
Immobility may result in calculi becauseof the stasis of urine
Calculi may form when:
There are excessive amounts of relativelyinsoluable salts in the filtrate
Insufficient fluid intake creates a highlyconcentrated filtrate
About 75% of calculi are composed ofcalcium salts, especially calcium oxalatethe remainder consisting primarily of uric
acid, struvite (magnesium ammoniumphosphate), or other oxalates
Foods high in oxalate include:
Dark green vegetables, such as spinach.
Rhubarb. Chocolate. Tea and cola. Wheat bran. Nuts. Cranberries. Beans. Coffee.
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Stones usually only cause problemswhen they obstruct the flow of urine,e.g. in the ureter
Calculi may cause infection becausethey cause stasis of urine in the areaand may also irritate tissues
When located in the kidney or ureter,calculi may cause the development ofhydronephrosis, with dilation of calycesand atrophy of renal tissue
Adult Polycystic Kidney
The most common form of this geneticdisease is transmitted as an autosomal
dominant gene on chromosome 16 No indications in the child or young
adult; first manifestations appeararound age 40
At this time renal failure occurs anddialysis is required
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Wilm’s Tumor
This is the most common tumor of the urinarytract occurring in children
Both a sporadic (most common) and inheritedform
The inherited form is associated with genes(WT1 & WT2) on chromosome 11 and mayoccur in conjunction with other congenitaldisorders including aniridia, hemihyperplasia,horseshoe kidneys, hypospadias, polycystic
kidneys, ureteral duplication and uterineabnormalities
It is usually unilateral
Usually diagnosed at about ages 2-5
when a large abdominal mass presents
With treatment of surgery, radiationand chemotherapy, survival rate about90%
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Renal Failure
Acute renal failure Sudden kidney failure
May be reversible if primary problem istreated successfully
Dialysis may be needed during treatmentperiod
In some cases, some permanent damageto the kidneys may occur
Acute Kidney Failure Etiology
Numerous causes:
Acute bilateral kidney disease such asglomerulonephritis
Severe and prolonged circulatory shock orheart failure
Shock associated with burns or crushinjuries (hemoglobin from hemolysis ofRBC’s causes obstruction of kidney tubules
Nephrotoxins such as drugs, chemicals ortoxins
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Chronic Renal Failure
Chronic renal failure is the gradualirreversible destruction of the kidneysover a long period of time. It mayoccur as a result of:
Chronic kidney disease
Bilateral pyelonephritis
Congenital polycystic kidney disease
Systemic disorders
Hypertension
Diabetes mellitus
Stages of Renal Failure
Decreased renal reserve (around 60%nephron loss) GFR reduced but no clinical signs)
Renal insufficiency (around 75%nephron loss: 25-30 ml/min GFR) Changes in blood chemistry
End-stage renal failure or uremia(around 90% nephron loss) Regular dialysis or kidney transplant
required to maintain patient’s life
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