Anatomy and Physiology of the Kidney, Urinalysis, Urinary System Disorders, Dialysis

1. RENAL
PATHOPHYSIOLOGY

2. Functions of The Renal System
◦Clearance of metabolic wastes from the blood and
removal from the body
◦Remove liquid waste from the blood in the form of
urine
◦Keep a stable balance of salts and other substances
in the blood
◦Produce erythropoietin, a hormone that aids in the
formation of RBC
◦Remove urea from the body through nephrons

3. Anatomy of the Renal System

5. Anatomy of the Renal System
◦2 Kidneys, where the work takes place
◦2 Ureters, to drain the kidneys and send urine to the bladder
◦1 Bladder, to store urine
◦1 Urethra, through which the urine exits the body

6. Kidneys
◦Bean-shaped organs located high on the posterior
abdominal wall
◦Functions:
◦Produce urine to rid of metabolic waste
◦Regulate water levels within homeostatic limits
◦Regulate blood pressure
◦Regulate acid-base balance or pH

7. Kidneys
◦Outer Coverings
◦Outer Renal Fascia – thin, fibrous connective shell that
fastens the kidneys to other structures
◦Middle Adipose Capsule – fatty layer cushioning the kidney
◦Inner Renal Capsule – directly covers the kidney, fibrous
membrane prevents the entry of infectious agents, and does
not stretch

8. Kidneys
◦ Internal Anatomy
◦ Renal Pelvis – funnel-shaped upper end of ureter
◦ Renal Hilum – concavity of medial border of kidney
◦ Renal Medulla – middle sections, consist of renal pyramid
◦ Renal Pyramids – divisions of the renal medulla, includes tubules and collecting
ducts of a nephron
◦ Renal Cortex – outer cortical region containing glomeruli and collecting ducts
◦ Major Calyx – division of renal pelvis that collects urine from renal pyramids
◦ Minor Calyx – division of major calyx that receives urine from major calyx
collected from renal pyramids

9. Internal Anatomy of the Kidneys

10. The Nephron
◦ Function – fundamental units of structure and function of the kidneys
◦ Anatomy – tubules/ducts drain into renal pelvis
◦ Renal Corpuscle
◦ Bowman’s Capsule – capsule-shaped membrane surrounding the
glomerulus of each nephron
◦ Glomerulus – rich network of blood vessels inside Bowman’s capsule;
capillaries carry a high blood pressure and receive blood supply from
afferent arteriole

11. The Nephron
◦Proximal Convoluted Tubule – reabsorbs useful materials
◦Descending Loop of Henle – reabsorbs water
◦Ascending Loop of Henle – reabsorbs salt
◦Distal Convoluted Tubule – takes in water, salt, and other
substances; secretes H+ and K+ ions into urine
◦Collecting Duct – carries filtrate to renal pelvis and
reabsorbs water with the influence of ADH

12. The Nephron

13. Glomerular Filtration Rate
◦Afferent Arteriole Dilation – increased filtrate
◦Efferent Arteriole Constriction – increased filtrate
◦Afferent Arteriole Constriction – increased filtrate

14. Renin-Angiotensin-Aldosterone Complex
◦Hormone system that regulates blood pressure and fluid balance
◦When renal blood flow is reduced, juxtaglomerular cells in the
kidney convert the precursor prorenin, already in the blood, to
renin and secrete it directly into the circulation
◦Plasma renin carries out the conversion of angiotensinogen,
released by the liver, to angiotensin I
◦Angiotensin I is subsequently converted to angiotensin II by
the angiotensin-converting enzyme (ACE) found in the lungs

15. Renin-Angiotensin-Aldosterone Complex
◦Angiotensin II is a potent vasoconstrictor resulting in
increased blood pressure, and it also stimulates secretion of
aldosterone from the adrenal cortex
◦Aldosterone causes the renal tubules to increase the
reabsorption of sodium and water in the blood, and increases
the excretion of potassium to maintain electrolyte balance
◦Renin is secreted in response to reduced afferent arteriole
blood flow.

17. Tracing Blood through the Glomerulus
to the Urethra
Glomerulus 
Water/Solutes through Glomerular Filtration Barrier 
Bowman’s Capsule 
Proximal Convoluted Tubule 
Nephron Loop 
Distal Convoluted Tubule 
Collecting Duct 
Minor Calyx 
Major Calyx 
Renal Pelvis 
Ureter 
Urinary Bladder 
Urethra

18. Physiology of the Nephron

19. Hormonal Regulation of Water Movement
◦ Aldosterone – indirect
◦ Acts to increase reabsorption of sodium; active reabsorption of sodium into blood is followed
by the passive movement of water
◦ Blood volume is increased, so urine volume is decreased
◦ Promotes active secretion of K+
◦ Antidiuretic Hormone – direct
◦ Produced by hypothalamus, stored/released by posterior pituitary
◦ Increases permeability of DCT and CD to water
◦ CD is only permeable to water if ADH is present
◦ Vasopressin – potent vasoconstrictor
◦ Atrial Natriuretic Peptide – indirect
◦ Produced by atrial muscle and inhibits sodium reabsorption
◦ Promotes excretion of sodium and water
◦ Blood volume is decreased, so urine volume is increased

20. Urine Formation
◦ Filtration
◦ From blood into nephron
◦ Creates plasma-like filtrate of blood
◦ Tubular Reabsorption
◦ From nephron into blood
◦ Removes useful solutes and water from filtrate and returns to blood
◦ Tubular Secretion
◦ From blood into nephron
◦ Removes additional wastes from the blood and adds them to filtrate

21. Urine Characteristics
◦Daily Urine Volume ~ 600mL to 1200mL per day
◦Composition
◦Water 95%
◦Solutes 95%
◦ Nitrogenous wastes
◦ Ketone bodies from fat metabolism
◦ Electrolytes, hormones, toxins, vitamins, and foreign chemicals
◦Physical Properties
◦Pale yellow color when diluted; becomes darker when concentration
◦pH ranges from 4.8 to 7.5; typically ~6.0

22. Urinalysis
◦ Cloudy – large amounts of protein, blood, bacteria, and pus
◦ Bloody
◦ Large Amounts – glomerular permeability or hemorrhage
◦ Small Amounts – infection, inflammation, or tumors in urinary tract
◦ Dark Color – hematuria, excessive bilirubin, highly concentrated
◦ Unusual Odor – sign of infection or result of diet/medication
◦ Elevated BUN and Creatinine – failure to excrete nitrogen waste
◦ Metabolic Acidosis – low pH and low bicarbonate indicates the
failure of tubules to control acid-base balance

23. Urinary Tract Infection
◦ Lower UTI – Cystitis and Urethritis
◦ Hyperactive bladder with reduced capacity
◦ Systemic signs with painful urination
◦ Upper UTI – Pyelonephritis
◦ Can occur in one or both kidneys
◦ Purulent exudate and abscess block blood and urine flow
◦ Systemic sign: high fever can lead to renal failure
◦ Cause – E. Coli
◦ Predisposing Factors – incontinence, urinary retention, or direct contact
with fecal material

25. Glomerulonephritis
◦Decreased glomerular filtrate
results in decreased urine output,
elevated blood pressure, edema, or
metabolic acidosis
◦Can produce bloody, foamy urine
and pain
◦Cause: acute post-streptococcal
glomerulonephritis is caused by
the presence of anti-streptococcal
antibodies

26. Nephrotic Syndrome
◦Increased permeability in
glomerular capillaries
◦Causes hypoalbuminemia,
increased aldosterone, and
severe edema

27. Bladder Cancer
◦Often develops as multiple
tumors
◦Early Signs
◦Hematuria
◦Dysuria
◦Predisposing Factors
◦ Working with chemicals,
recurrent infections
◦ Smoking, heavy analgesic intake

28. Vascular Disorders
◦Thickening and hardening of walls and small arteries
◦Reduces blood to kidney-stimulation of renin and increases
blood pressure
◦Can be normal with aging

29. Adult Polycystic Kidney Disease
◦Manifests around 40 y/o
◦Multiple cysts in both kidneys
◦Can lead to chronic renal
failure
◦Cause: autosomal dominant
gene on chromosome 16

30. Pediatric Polycystic Kidney Disease
◦Manifests at birth
◦Child dies in the first month
or is stillborn
◦Cause: autosomal recessive
mutations

31. Acute Renal Failure
◦ Rapid onset
◦ Produces metabolic acidosis, hyperkalemia, oliguria, and increased
serum urea
◦ Can have a variety of causes:
◦ Acute Bilateral Kidney Disease
◦ Prolonged or Severe Circulatory Shock
◦ Heart Failure
◦ Nephro-toxins
◦ Mechanical Obstruction
◦ Burns

33. Chronic Renal Failure
◦ Gradual, irreversible destruction of the kidneys
◦ Asymptomatic at first
◦ Symptoms later on: polyuria with dilute urine, anemia, fatigue, and
axotemia
◦ Causes:
◦ Chronic Kidney Disease
◦ Polycystic Kidney Disease
◦ Systemic Disorders
◦ Low-level nephrotoxin exposure over a long period of time

36. Kidney Stones
◦Calcium, magnesium,
uric acid, cysteine
◦Very painful
◦1mm to 5mm can be
passed

37. Wilms Tumor
◦Usually unilateral and gives
purely kidney symptoms
◦Most common tumor in children
◦Cause: defects in
tumor=suppressor gene on
chromosome 11

38. Neuropathy
◦Diabetic Neuropathy
◦ Leading cause of
chronic renal failure

39. Neuropathy
◦Reflux Neuropathy
◦ Flow of urine from the bladder to the upper urinary tract
◦ Can lead to end stage renal disease
◦ Associated with hypertension
◦ Primary = congenital, secondary = obstruction

41. Incontinence
◦Stress Incontinence
◦ Most common. Happens when someone sneezes.
◦Urge Incontinence
◦ Spasm
◦Overflow Incontinence
◦ Can’t fully empty the bladder
◦Functional Incontinence
◦ Bladder is normal
◦ Something else keeps them from going to the bathroom, such as a spinal
cord injury

42. Dialysis
◦Provides filtration and reabsorption
◦Hemodialysis
◦ Blood moves from shunt into a machine
◦ 3 times per week for 4 hours
◦Peritoneal Dialysis
◦ Peritoneal membrane serves as a semi-permeable membrane
◦ Usually done at home or during night