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Urinary System

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 . KIDNEYS. Filter blood, produce urine (24 hrs a day)

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Urinary System

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  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

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

  3. 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

  4. 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

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

  6. 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

  7. 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

  8. 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

  9. 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

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

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