1. Urinary System URINARY SYSTEM ORGANS: Ureters –Collect urine from kidneys, bring to bladder Bladder –Muscular, elastic organ – holds about 250ml Urethra –Longer in males than in females –Two sphincters: involuntary & voluntary

4. KIDNEYS Filter blood, produce urine (24 hrs a day) Cortex and medulla; At hilus, artery in, vein and ureter out

6. Nephron Structure Bowman’s capsule & glomerulus –Filtration occurs here –Pressure forces filtrate through cell gaps –Formed elements (blood cells), large proteins stay in blood –Water, ions (salts), nutrients, wastes go through 180 liters filtrate per day Proximal convoluted tubule –Majority of reabsorption occurs here. 179 liters reclaimed to peritubular capillary network

8. –Water, salt, glucose, amino acids back to the blood (nutrients in general) Secretion – removal from blood of wastes that escaped filtration –Loop of Henle ( ascending and descending limbs) –Distal convoluted tubule –Collecting duct

9. Nephron Functions Filtration: Bowman’s capsule, glomerulus) Reabsorption: Proximal convoluted tubule Secretion: Loop of Henle, Distal convoluted tubule, Collecting duct

10. Concentration of Urine Kidneys regulate water-salt balance of the blood. Kidney cells use ATP to set it up (pump NaCl & urea leaks into renal medulla) Descending loop of Henle: water diffuses into salty medulla tissue Ascending loop of Henle: not water permeable!!!!! Salt is actively pumped out

11. Distal convoluted tubule and collecting duct: water permeability under hormonal control ADH (Antidiuretic hormone-secreted by pituitary gland) –Increases urine concentration –When ADH decreases, kidneys make dilute urine –Alcohol interferes with ADH secretion  dilute urine, you lose water – coffee too

12. Urine Composition 95% water by volume; rest is solutes Nitrogenous wastes: urea, creatinine, uric acid Ions: sodium, potassium, sulfate, Associated with medical problems: glucose, blood proteins (albumin), red or white blood cells, bile pigments

13. Renal Failure Symptoms: –Acidosis – low blood pH - kidneys excrete hydrogen ions –Anemia – low RBC count – erythropoietin –Edema – water and salts retention –Hypertension – high blood pressure –Accumulation of nitrogenous wastes (urea) Hemodialysis – artificial kidney Kidney transplant

14. Kidney Stones Mineral crystals (often calcium) that form in the kidney and pass down ureter. Prevention: drink plenty of water