urinary system. structure and parts mentioned
- 2. INTRODUCTION • Cellular metabolism produces wastes • CO2 • Urea • Ammonia • Kidneys rid the body of most nitrogenous wastes • Kidneys regulate the chemical make- up of blood
- 3. Definition The urinary system is the main excretory system of the body , which expel the waste and excess material from the body. This urinary system is also know as Excretory system or Renal system
- 4. GENERAL FUNCTIONS Maintaining homeostasis of water and electrolyte concentration Excretion of metabolic waste material from the body in the form of urine Excretion of nitrogenous compounds urea and uric acid Excretion of excess ions and some drugs Maintain acid base balance Production and secretion of erythropoietin Production and secretion of Renin
- 5. ORGANS OF THE URINARY SYSTEM • Kidneys (paired) which secrete urine • Ureters(paired Transport urine from kidney to urinary bladder • Urinary bladder (single) • Stores urine
- 7. EXTERNAL STRUCTURE OF THE KIDNEY • Renal capsule • Connective tissue • Renal artery • Blood (oxygenated) to the kidney • Renal vein • Receives blood from kidney • Ureter • Drains urine
- 8. INTERNAL STRUCTURE OF THE KIDNEY •Renal cortex •Renal medulla • Renal pyramids •Renal pelvis • Continuous with ureter •Calyces • Extensions of the pelvis • Function – collect urine
- 9. STRUCTURE OF THE KIDNEY Human Anatomy, 3rd edition Prentice Hall, © 2001
- 10. BLOOD SUPPLY OF THE KIDNEY • Approximately ¼ of the total blood supply of the body passes through the kidneys each minute • Renal artery branches inside the kidney • Supplies the pyramids and the cortex • Venous blood leaves the cortex and medulla • Small veins join the renal vein
- 11. BLOOD SUPPLY OF THE KIDNEY
- 12. NEPHRONS AND URINE FORMATION •Nephrons form the urine product •Filtration •Reabsorption •Secretion •Each kidney contains about 1 million nephrons
- 13. STRUCTURE OF A NEPHRON • 2 main structures • Glomerulus – a knot of capillaries • Renal tubule (about 2 inches long) • Bowman’s capsule surrounds the glomerulus • Proximal convoluted tubule • Henle’s Loop • Distal convoluted tubule • Renal tubule enters collecting duct • Receives urine from nephrons • Delivers final urine product into the calyces
- 16. RENAL CORPUSCLES
- 18. BLOOD SUPPLY OF THE NEPHRON
- 19. URINE FORMATION • Filtration • Blood in afferent arteriole is under high pressure • Glomerulus acts as a filter • Filtrate = the substance that is filtered from the blood into the renal tubule • Blood leaves the glomerulus through the efferent arteriole • Reabsorption • Filtrate contains useful substances which are returned to the blood • Most occurs in the proximal convoluted tubules • Secretion • Substances move from blood (capillaries) into the filtrate • Important in controlling pH of blood
- 20. CONTROL OF BLOOD COMPOSITION BY KIDNEYS • Excretion of nitrogen-containing compounds • Urea • Uric acid • Water and electrolyte balance • Regulated by hormones • ADH – increases water reabsorption • Aldosterone – increases sodium reabsorption • Second effect of aldosterone – increase water reabsorption. • Acid-base balance of blood • Blood pH must be 7.35 – 7.45 (very narrow range) • Tubule cells secrete whatever is necessary into filtrate • Urine pH = 4.5 – 8.0
- 21. SUMMARY OF URINE FLOW •Kidneys produce urine • Filtration • Reabsorption (active transport) • Secretion •Ureters •Bladder •Urethra