Diseases of the Kidney and Urinary Tract

- surrounded by insulating fat
- in connective tissue behind abdominal cavity (retroperitoneum)
- concave aspect (hilum) where blood vessels, nerves and urinary tract enter
- renal cortex is outer 1/3, inner 2/3 is medulla
- medulla consists of pyramids whose bases face the cortex and tips have small openings of collecting duct that empty into renal pelvis

- urine propelled by contractions along ureter
- ureter goes to bladder that holds 500 cc
- bladder empties at base via urethra

- 20 cm in males
- 4 cm in females
- higher incidence of urinary tract infection and incontinence in women
- urethra passes through prostate in male - plays role in sexual function and when it enlarges, obstructs urinary tract in older men

- glomerulis (tuft of capillaries) with long epithelial tubes that collect and concentrate urine
- glomerulus surrounded by double walled epithelial capsule (bowman's)
- space inside capsule collects fluid that is pressed through capillaries
- fenestrations allow passage of fluid
- glomerular basement memrane is mesh where small molecules pass through and proteins can't leave
- GBM repel negatively charged proteins in blood
- both physical and charge barrier
- glomerular kidney disease - damage to GBM
- final barrier from capillary space to urinary space - podocytes (finger like processes) with slits

- enter proximal convoluted tubule which reabsorbs 2/3 of filtered water and sodium, glucose, amino acids
- travels to loop of Henle that goes towards middle of kidney and then back to cortex
- through active pumping, epithelial cells in loop are responsible for creation of concentration gradient that allows for further reabsorption of water and ions
- enters distal convuluted tubule and leaves through collecting duct
- this tubing forms the pyramids, and all cllecting ducts converge at tips of pyramids
- urine empties into renal pelvis and is propelled to bladder

- all lined by multilayered epithelium of transitional cells
- surrounded by smooth muscle

- elimination of drugs, toxins, poisons, metabolic waste
- maintenance of electrolyte concentrations
- maintenance of water balance
- regulation of pH
- regulation of BP
- regulation of vitamin D by converting it to active form
- releasing hormone, erthropoietin

- pre-renal (septic shock, dehydration, hemorrhage, heart failure)
- renal (acute tubular necrosis, acute glomerulonephritis)
- post-renal (urinary tract obstruction)

- edema
- increased levels of sodium, potassium, phosphate
- metabolic acidosis
- build up of nitrogenous wastes in blood
- decreased erythropoietin synthesis (anemia)
- hypertension (sodium and water retention, increased renin - renin regulates BP)
- bone disease (renal osteodystrophy) - increased blood phosphate and impaired reabsorption of calcium = low blood calcium... body reabsorbs more from bone; decreased activation of vit D
- accumulation of waste products (itching, nausea, vomiting, decreased appetite, ulcers, inflammation of tissue, blood clotting problems, WBC dysfunction, nerve and muscle dysfunction, drowsiness, coma, death)

- acute is reversible , rapid onset of symptoms
- chronic is irreversible and loss of function, can result from loss of glomeruli, hypertension, chrnic urinary tract obstruction, diabetes, lupus... clinically silent at first

- major causes of chronic renal failure
- can be confused with malignant tumours
- some are hereditary and have implications for family members

- autosomal dominant inheritance
- mutations in three separate genes
- PKD1 gene on chromosome 16 codes for polycystin which is involved in cell-cell and cell-matrix interactions in kidney, liver, pancreas
- mechanisms are unclear, but los of protein results in altered growth regulation and differentiation of tubular epithelial cells... cysts form
- one of most common causes of renal failure
- affects BOTH kidneys... become enlarged and functional tissue replaced by thin-walled cysts which contain fluid
- cysts destroy nephrons, chrnic renal failure occurs... affects liver, pancreas, spleen
- predisposed to aneurysms in blood vessels of brain

- different genes affected
- autsomal recessive inheritance
- develop in childhilld... earlier symptoms
- predisposed to liver fibrosis
- dilated cortical and medullary collecting ducts arranged radially... external surface smooth

- primary - affect glomerulus primarily or exclusively
- secondary - affect multiple organs, including kidney... diabetes, lupus, vasculitis

- abnormal immune reaction resulting in deposition of antibodies or antigen-antibody immune complexes in GBM