Renal Pathophysiology

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

4. 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

5. 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

6. 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

7. 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

8. Internal Anatomy of the Kidneys

9. 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

10. 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

11. The Nephron

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

13. 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

14. 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.

15. 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

16. Physiology of the Nephron

17. 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

18. 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

19. 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

20. 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

21. 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 P urulent 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

22. 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

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

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

25. 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

26. 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

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

28. 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

29. 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

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

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

32. Neuropathy Diabetic Neuropathy Leading cause of chronic renal failure

33. 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

34. 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

35. 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