URS Pathology 1 PDF

# Introduction to the Urinary System ## Definition of the nephron: - It's the microscopic structural and functional unit of the kidney. ## The nephron is composed of: - 1- The renal corpuscle consists of a tuft of capillaries called a glomerulus inside Bowman's capsule. - 2- The renal tubule; exte...

# Introduction to the Urinary System ## Definition of the nephron: - It's the microscopic structural and functional unit of the kidney. ## The nephron is composed of: - 1- The renal corpuscle consists of a tuft of capillaries called a glomerulus inside Bowman's capsule. - 2- The renal tubule; extends from Bowman's capsule ## Histology: - Endothelium: lining of tuft capillaries - Epithelium/Podocyte: lining of Bowman's capsule - In between them is a basement membrane ## The glomerulus (plural glomeruli): - Is a network of capillaries known as a tuft, located inside the Bowman's capsule. - This tuft is supported by the mesangium; supporting background of blood vessels made up of intraglomerular mesangial cells. ## Syndrome: - A set of medical signs and symptoms which are correlated with each other and often associated with a particular disease or disorder. # Nephritic Syndrome - It is a name given to a collection of different signs and symptoms that occurs as a result of inflammation in the kidney. - **Characters (signs & symptoms):** - Hematuria - Oliguria: Passing less urine - Hypertension - Uremia: Elevated blood urea & creatinine (BUN) < 3.5 - Azotemia: Elevated nitrogen-rich waste compound in the blood - Edema: Face or leg - Mild to moderate proteinuria ## Caused by: - Deposition of immune complexes from antibodies against organisms & complement fragments cause acute inflammatory response in the glomeruli. - **Example**: Type III hypersensitivity - Acute diffuse proliferative glomerulonephritis (post streptococcal or acute glomerulonephritis) (most frequent in children) - It follows the infection of the upper respiratory tract by nephritogenic strains of group A beta hemolytic streptococci ## Gross picture: - Kidneys may be slightly enlarged and pale due to edema # Nephrotic syndrome - A kidney disorder that causes your body to pass too much protein in urine caused by damage to glomeruli - **Characters**: - Heavy proteinuria (Albuminuria) - Hypo-proteinemia - Severe generalized edema - Hyperlipidemia: The main cause is increased hepatic lipogenesis secondary to hypoalbuminemia ## Caused by: - Damage to glomeruli (tuft of capillaries) - **Examples and causes**: - Glomerulonephritis: membranous, membranoproliferative and minimal change glomerulonephritis - Systemic lupus erythematosus (SLE) - Diabetes - Amyloidosis: deposition of abnormal misfolded protein - Infections; malaria, viral B and C hepatitis - Nonsteroidal anti-inflammatory Drugs ## Gross picture: - Enlarged & pale Kidneys due to edema - **Yellowish color** due to presence of lipid resorbed from the urine into the renal tubular epithelium. # Microscopic picture: - **Nephritic syndrome** - All glomeruli: are enlarged & hypercellular due to proliferation of endothelial and mesangial cells and infiltration by neutrophils & monocytes - Blood vessels: Swelling of endothelial cells and presence of inflammatory cells obstructs capillary lumen - Tubules contain red cell casts - Interstitium: Slight leucocyte infiltrate and edema - Immunofluorescence: granular fluorescence deposited at glomerular capillary walls & mesangium for IgG-IgM & C3 - Electron Microscopy: subepithelial (between epithelial cells of Bowman's capsule, & basement membrane) electron dense deposits known as subepithelial humps: finely granular, dome-shaped,, representing immune complex deposits # Prognosis: - **Children:** age 6-10: nephritic presentation after 1 - 4 weeks strep infection of pharynx - 95% recover with conservative therapy - 1-2% develop rapidly progressive glomerulonephritis - 2-3% develop chronic glomerulonephritis - **Adults:** may have atypical presentation with sudden hypertension, edema and elevated BUN (Blood Urea Nitrogen) - 60% recover - 40% develop rapidly progressive glomerulonephritis # Microscopic picture: - **Nephrotic syndrome** - Fusion (effacement) of the foot processes of the podocytes by electron microscopy - _The tubules show:_ - Hyaline degeneration of the epithelium of the tubules due to resorption of protein from the urine. - Vacuolar degeneration of the epithelium of the tubules due to resorption of lipids from the urine. - Protein casts within the tubular lumen - Interstitium show: variable edema | Normal Capillary | Minimal Change Glomerulopathy | |:--:|:--:| | [Image of normal capillary] | [Image of minimal change glomerulopathy] | ## Pathophysiology: - Injury to podocytes - Podocyte foot process effacement & detachment - Protein leaks into ultrafiltrate (urine) ## Signs/symptoms: - High proteinuria > 3.5 g/day - Hypoalbuminemia - Water & Na+ retention - Edema - Hyperlipidemia/lipiduria - Loss of Immunoglobulins & anticoagulants in urine. - Infections, thrombotic complications "Foamy urine is a sign of proteinuria" "Pitting" edema