Urinary Pathophysiology

1. The Urinary System

2.  Kidney functions
 Other system organs
 General system
anatomy
 Kidney str & fxn
 Nephron – basic fxnal
unit of the kidney
Overview

3. Kidney Functions
 Filter 200L blood/day to eliminate:
 Toxins
 Metabolic wastes
 Excess ions
 Regulate blood volume
 ~ 5 L
 Regulate chemical makeup of the blood
 300 mmoL concentration of solutes (i.e.
sodium, potassium, zinc)
 Maintain the proper balance between H20 &
salts, and acids and bases.

4. Other Kidney Functions
 Gluconeogenesis
 Production of renin
 Production of erythropoietin
 Activation of vitamin D

5. Other Urinary System Organs
 Urinary bladder – provides
temp. storage reservoir for
urine
 Paired ureters – transport urine
from the kidneys to the bladder
 Urethra – transports urine from
the bladder out of the body

7. Ureters
 Slender tubes-carry urine: kidneys to the bladder
 Ureters enter the base of the bladder through the
posterior wall
 As bladder pressure increases (increased urine
volume in bladder), distal ends of ureters get closed
off & prevent backflow of urine into ureters.
 Tri-layered wall
 Epithelial mucosa
 Smooth muscle
 Fibrous connective tissue
 Ureters actively propel urine to the bladder via response
to smooth muscle stretch

8. Urinary Bladder
 Smooth, collapsible, muscular sac that temporarily
stores urine
 Lies on the pelvic floor posterior to the pubic symphysis
 Males – prostate gland surrounds the neck inferiorly
 Females – anterior to the vagina and uterus
 Trigone – triangular area outlined by the openings for
the ureters and the urethra
 Clinically important because infections tend to persist
in this region

10. Urinary Bladder
 The bladder wall has three layers
 epithelium
 muscular layer
 fibrous layer
 The bladder is distensible &
collapses when empty
 As urine accumulates, the bladder expands without
significant rise in internal pressure

11. Bladder Cancer
 60,000 cases a year in the US
 13,000 deaths per year
 4 times more likely to occur in men
 Most frequently b/w 60-70 yrs of age
 Causes ?
 Environmental exposures
High rates in employees in chemical and rubber
plants
 Prognosis for metastatic bladder cancer is poor
 Spreads to bone, lymphatic system

12. Tissue engineering: Bladder
 Bladder disease
 Increased pressure in poorly functioning bladder
leads to kidney damage
 Reconstruction w/ small intestine tissue
 Grow own bladder cells in culture for 7-8 weeks
 Attached ‘new bladder’ to old bladder in 7, 4-19 yr old
children
 2-5 yrs later: improved bladder function in all
subjects

13. Urethra
 Muscular tube that:
 Drains urine from the bladder
 Moves urine out of the body

14.  Sphincters keep the urethra closed when urine is not
being passed
 Internal sphincter – involuntary sphincter at the
bladder-urethra junction
 External sphincter – voluntary sphincter surrounding
the urethra as it passes through the urogenital
diaphragm
 Levator ani muscle – voluntary urethral sphincter

17.  The female urethra is tightly bound to the anterior
vaginal wall
 External opening lies anterior to vaginal opening and
posterior to the clitoris
 The male urethra has 3 named regions:
 Prostatic urethra – runs within the prostate gland
 Membranous urethra – runs through the urogenital
diaphragm
 Spongy (penile) urethra – passes through the penis
and opens via the external urethral orifice

18. Prostate Gland Surrounds Urethra

19. Prostate Gland:
 Size of walnut
 Surrounds neck of urinary
bladder and urethra
 Secretes fluid that forms part
of semen

20. Benign Prostate Disorders
 Infection
 Inflammation
 Enlarged prostate
 High blood levels of PSA
 Impotence
 Incontinence and or retention
 S&S of prostate disorders
 Interference of flow
 Change in urinary freq. urination
 Pain

21. Prostate CA
 Increased likelihood with enlarged prostate
(hypertrophy).
 60% of prostate cancers discovered remain localized
 5 yr survival = 100%
 10 yr survival = 68%
 15 yr survival = 52%
 In past 20 yrs survival has increased from 67-93%

22. Other Considerations
 PSA check annually after age 50
 High risk males should begin screening
earlier
 Risk factors
 Age
 Race
African Americans are 61%
more likely to get prostate CA &
2.5x more likely to die from dx
 Diet: high fat / low fiber
 Obesity
 Environmental exposures

23. Kidney Location & Structure
 Bean-shaped
 extends from T-12 to L-3.
 R kidney hangs lower than left.
 crowded by the liver

24. Layers of Tissue Support
 Renal capsule – fibrous capsule surrounding kidneys
that gives support & helps prevent infection
 Adipose capsule – fatty mass that cushions the kidney
and helps attach it to the body wall
 Renal fascia – outer layer of dense fibrous connective
tissue that anchors the kidney

26. Internal Structure of Kidney
 Cortex – the light colored, granular superficial region
 Medulla – exhibits cone-shaped medullary (renal)
pyramids
 Pyramids are made up of parallel bundles of urine-
collecting tubules
 Renal columns are inward extensions of cortical tissue
that separate the pyramids
 Pyramid plus its surrounding capsule, constitute a
lobe

28. Large blood flow to kidney:
~25% (1200 ml) of BF from heart
into systemic circulation, flows
through the kidneys per minute.

29. The Nephron
 Nephrons: stral & fxnal units of the kidneys that form
urine:
 Glomerulus: a capillary bed associated with a renal
tubule
 Bowman’s capsule: cup-shaped end of a renal tubule
that surrounds glomerulus.
 Renal corpuscle – the glomerulus and its Bowman’s
capsule
 Glomerular endothelium –epithelium that allows
solute-rich, virtually protein-free filtrate to pass from
the blood into the glomerular capsule

33. Renal Tubule
 Proximal convoluted tubule (PCT):
 Composed of cuboidal cells with numerous microvilli
and mitochondria
 Reabsorbs water and solutes from filtrate and
secretes substances into it
 Loop of Henle: a hairpin-shaped loop of the renal tubule
 Distal convoluted tubule (DCT):
 cuboidal cells w/o microvilli that function more in
secretion than reabsorption

34. Nephrons
 Cortical nephrons – 85% of nephrons; located in the
cortex
 Juxtamedullary nephrons:
 Located at the cortex-medulla jxn
 Have loops of Henle that deeply invade the medulla
 Have extensive thin segments
 Are involved in the production of concentrated urine

35. Capillary Beds of the Nephron
 B/P in the glomerulus is high:
 Kidney is very well vascularized
 High density of blood vessels
 Blood flow within nephron controlled by afferent
arteriole
 Fluids & solutes are forced out of the blood
throughout the entire length of the glomerulus

36. Characteristics of Normal Urine
• Complex watery (95%) solution of organic &
inorganic wastes (5%)
• Color: pale, straw to amber color
– If highly concentrated:
•Hematuria / orange color
–‘milky’ / turbid : infection
• Clarity: transparent
• Odor: faintly aromatic; will change to ammonia
if standing too long. Some drugs and vegetables
(asparagus) alter the usual odor
• pH: 5.5 – 7.0
– Will turn alkaline if left standing

37. Characteristics of Normal Urine
 Specific Gravity:
 Indicates concentration of urine (# of particles in it)
 Normal values = 1.01 – 1.03
Measured by comparing the weight of pure water
vs. urine
 Urine should not contain:
 Albumin
 Glucose
 Ketones
 Blood / Pus / Bacteria
 Calculi
 Bile

38. Normal Output
 Normal voiding: 250 – 500cc
 Normal 24 hour voiding: 1000
- 1500cc
 Normal hourly: 30 -120cc
 < 30cc / hr may indicate renal
pathology

39. Chemical Composition of Urine
 Urine is 95% water and 5% solutes
 Nitrogenous wastes include urea, uric acid, and
creatinine
 Other normal solutes include:
 Na+, K+, phosphate, and sulfate ions
 Calcium, magnesium, and bicarbonate ions
 Abnormally high concentrations of any urinary
constituents may indicate pathology

41. Trauma, Ischemia & Kidney Damage
 Ischemia – decreased oxygen supply to nephron because
there is decrease in blood flow
 Decreased blood flow to nephron which is chronic can
lead to Kidney Damage.
 Anything that causes afferent arteriole prolonged
constriction

42. Renal Clearance Diagnostic Test
 The volume of plasma that is cleared of a particular
substance in a given time
 Clearance tests are used to:
 Determine the GFR
 Detect glomerular damage
 Follow progress of renal dx

43. Renal Clearance
RCR = UV/P
RCR = renal clearance rate
U = concentration (mg/ml) of the substance in urine
V = flow rate of urine formation (ml/min)
P = concentration of the same substance in plasma

44. Urinary Disorders: S&S
 Changes in urinary frequency
or volume
 Dark urine
 Pain with urination
 Kidneys unable to regulate
body H2O & Na+ balance
 Edema (fluid retention) &
or High B/P

45. Urinary Tract Patho
 Urinalysis
 General health of urinary sys
 Drug testing
 Proteinuria
 Glomerular damage
 Ketonuria
 Diabetes or starvation
 Glucosuria
 Diabetes
 Solids in urine - sediment examined.
 Types of cells: RBCs ; WBCs
 Ability of kidneys to concentrate urine
 Administer ADH
become more concentrated since more fluid
should be retained

46. Urinary Tract Infections
 Occurs in any portion of urinary
tract
 10 - 20% of all women in US have
lower UTI at some time
 Limited occurrence
 Effects of urea (kill bacteria)
 Acidic pH of urine
 Washing out of bacteria during
voiding
 Minimize urine reflux

47.  Cystitis
 Bladder inflammation
Increased urination
 frequency & urgency
Pain
Cloudy urine
Blood in urine
 Treatment: ABx thpy

48. Kidney Infection
 Bacterial or viral
 Urinary obstruction
 causes backflow of urine from bladder to kidneys
 From blood infection
 Most cases in women
 Symptoms
 Pain / Fever
 Increased urinary frequency
 Treatment
 Longer use of ABx thpy

49. Urolithiasis
 Presence of stones in the
urinary tract
 Calculi formed by:
 Calcium oxalate
 Calcium phosphate
 Uric acid
 Calculi can pass through
the urinary tract and/or
cause an obstruction

50. Urolithiasis
 Assessment:
 Acute, sharp, intermitte
nt pain (ureteral colic)
 Dull, tender ache in the
flank (renal colic)
 N&V, Fever & chills
 Hematuria / Pyuria
 Abd. Distention
 Diagnostic Findings:
 KUB: visible calculi
 IVP: size & loc of stones
 Renal sonogram &
Spiral CT scan
 Stone Analysis –
detection of type of
stone

52.  Non-Surgical Procedures:
 Extracorporeal Shock Wave
Lithotripsy
 Stone dissolution
 Laser impulse technology
 Surgical Procedures:
 Cystoscopy
 Ureterolithotomy;
Pyelolithotomy; Nephrolithotomy

55. Polycystic Kidney Disease
 Genetic disorder - 500,000 cases in US
 Large cysts form in the kidneys
 Kidney hypertrophy
 Over time, decreasing kidney function as nephrons units
are replaced by cysts
 Dialysis or transplant
 50% with PKD progress to kidney failure (end stage
renal disease)
 4th leading cause of kidney failure
 No cure except kidney transplant

56. Polycystic Kidney Disease

57. Acquired Cystic Kidney Disease
 From long-term kidney dialysis and end-stage renal
disease
 90% of people on dialysis for 5 yrs develop ACKD
 Cysts may bleed
 Increased risk of kidney cancer (very rare)
 2 times as likely with ACKD

58. Diabetic Nephropathy
 Diabetes - Abnormally high blood glucose
 Causes major problems with blood chemistry
including osmotic balance
 Kidneys can remove all extra glucose from blood
Kidneys must work extra hard to do this
 Larger urine volume as kidneys must excrete excess
glucose

59. Diabetic Nephropathy (con’t)
 Prolonged high blood glucose causes nephropathy
 Damage to the glomerulus and the filtering system
 Proteins and blood cells that would normally not be
filtered appear in the urine
 Kidney function is compromised
 Diabetic nephropathy is leading cause of kidney failure
in United States

60. Diuretics
 Chemicals that enhance the urinary output include:
 Any substance not reabsorbed
 Substances that exceed the ability of the renal tubules
to reabsorb it
At transport max
 Substances that inhibit Na+ reabsorption
Na+ drives the reabsorption of fluid

61. Osmotic diuretics include:
 High glucose levels
H2O carried out w/ glucose
 Alcohol
inhibits release of ADH
 Caffeine and most diuretic drugs
inhibit Na+ reabsorption
 Lasix
 inhibit Na+ associated transporters

63. Diuretics to Treat Urinary System Dx
 Diuretics: increase urine volume
 Aldosterone antagonists: block sodium retaining
effect of aldosterone
More sodium remains in renal tubule
 More sodium excreted
 Where sodium goes, water goes (increased fluid
elimination
 Sodium and chloride reabsorption inhibitors
(thiazides)
block reabsorption of sodium, potassium and
chloride
 Increased salt and water elimination

65. Treatment of Renal Failure
 Will develop after both kidneys are damaged
 Restrict water, salt and protein intake
Minimizes volume of urine produced
Prevent production of large amount of nitrogenous
waste
 Hemodialysis
 Uses artificial membrane (replaces glomerular
filtration) to filter blood.
Diffusion of small ions
Minimal loss of blood protein
 Dialysis fluid
K+, phosphate ions, sulfate
ions, urea, creatinine, uric acid go into dialysis

66. Treatment of Renal Failure
 Dialysis
 15 hrs per week
 Dialysis centers
 Transplantation
 15,000 transplants in 2003
 1 yr success rate is 85-95%
 Immunosupressive drugs to reduce transplant
rejection

68. Urinary Incontinence – Multiple Etiologies
 Normal effect of aging or pathology
 Stretching of pelvic floor during childbirth
 Incontinence during sneezing and coughing (stress
incontinence)
 Prostate removal
 Neurogenic bladder dysfunction
 Treatment
 Kegel exercises: tightening pelvic muscles as if trying
to stop urination

70. Did you know?
 Infants have small bladders and the kidneys cannot
concentrate urine, resulting in frequent micturition
 Control of the voluntary urethral sphincter develops
with the N System about age 1
 E. coli bacteria account for 80% of all urinary tract
infections
 Sexually transmitted diseases can also inflame the
urinary tract and result in urinary tract infections
 Kidney function declines with age, with many elderly
becoming incontinent