The Urinary System

1. Chapter 30 The UrinarySystem

2. Chapter 30 The Simple ExcretorySystem of a Flatworm FlameCell ExcretoryPores Nucleus Cilia Pharynx ExcretoryTubule

3. Chapter 30 Excretory Systemof the Earthworm Nephridia Coelom Nephrostome ExcretoryPore Intestine Ventral Nerve Cord

4. Chapter 30 Formation & Excretionof Urea 1 In cells, amino acidsare metabolized,releasing ammonia. 2 In liver, ammonia is combined with CO2 to make urea. 1 In cells, amino acidsare metabolized,releasing ammonia. AmmoniaNH3 3 In kidneys, urea + water + other wastes = urine. ureaNH2-C-NH2||O Carriedin blood 2 In liver, ammonia is combined with CO2 to make urea. excretedinurine ureaNH2-C-NH2||O AmmoniaNH3 Carriedin blood 1 In cells, amino acidsare metabolized,releasing ammonia. AmmoniaNH3 Carriedin blood 2 In liver, ammonia is combined with CO2 to make urea. ureaNH2-C-NH2||O Carriedin blood 3 In kidneys, urea + water + other wastes = urine. excretedinurine

5. Chapter 30 The Path of wastes through the system • The human kidneys are paired, bean shaped organs located on either side of the spinal column extending slightly above the waist. • Each is 5 inches long and 3 inches wide, 1 inch thick. • Blood carrying dissolved waste enters each kidney through the renal artery. • After the blood is filtered, it exits through the renal vein. • Urine leaves the kidney via the ureter- a narrow muscular tube. Fig 30-5 p.608

6. Chapter 30 The Human Urinary System Renal Artery Kidney Renal Vein Vena Cava Aorta Ureter UrinaryBladder

7. Chapter 30 • Ureter- uses peristaltic contractions to transport urine to the urinary bladder ( the bladder) • Bladder- a hollow, muscular chamber that collects and stores urine. The walls of the bladder contain expandable smooth muscle. • Urine is kept in the bladder by 2 sphincter muscles located at the base above the junction of the urethra. • When the bladder fills, receptors on the walls signal the condition and triggers reflex contractions.

8. Chapter 30 Bladder (cont’d) • Internal sphincter – sphincter closest to the bladder opens during this reflex. • External sphincter – lower sphincter is under voluntary control so the brain can suppress the reflex unless the bladder distension becomes acute. • An average adult bladder can hold 500 mL of urine but the need to urinate is triggered by smaller amounts. • Urine makes its way out via the urethra. It is 1.5 inches in females and 8 inches long in males

9. Chapter 30 Storage and Excretion of Urine • Ureter • Bladder • Urethra

10. Chapter 30 The Human Urinary System Ureter UrinaryBladder Urethra(in penis)

11. Chapter 30 Urine Formation • Urine is formed in the kidneys. • Each kidney has a solid outer layer where urine is made. • There is also a subdivided inner chamber called the Renal pelvis – collects urine and funnels it to the ureter. • The outer layer of the kidney includes the renal cortex overlying the renal medulla. • This outer layer has an array of tiny filters called nephrons, which is filled with blood vessels.

12. Chapter 30 Cross Section of a Kidney RenalPelvis RenalCortex RenalArtery Nephron RenalMedulla RenalVein RenalPelvis Ureter

13. Chapter 30 Kidney Function Summary • Waste removal • Filtration by the glomerulus • Urine formation in the nephron • Tubular reabsorption • Tubular secretion • Production and concentration of urine • Maintenance of homeostasis • Regulation of water content in the blood • Regulation of levels of molecules in the blood • Maintenance of blood pH • Regulation of blood pressure and oxygen content

14. Chapter 30 The Nephron • The glomerulus – a dense knot of capillaries from which the fluid from the blood is collected. • Bowman’s capsule – a surrounding cup-like structure. • Tubule – a long twisted tube divided into: • i. Proximal tubule • ii. Loop of Henle – extends into the renal medulla • iii. Distal convoluted tubule – leads into the collecting duct

15. Chapter 30 An Individual Nephronand Its Blood Supply Collecting Duct Distal Tubule Proximal Tubule Bowman’s Capsule Arterioles Branches ofRenal ArteryRenal Vein Loop of Henle Capillaries

16. Chapter 30 What does the kidney filter? 2 million nephrons Filter 180 litres/day All but 1.5 litres is reabsorbed Minimum output of urine is 300-400 mL/day

17. Chapter 30 Material Filtered in 24 Hrs

18. Chapter 30 Kidney function-waste removal • a. Filtration by the glomerulus • Water, nutrients and wastes are forced into fluid in Bowman’s capsule by pressure in the capillaries of the glomerulus

19. Chapter 30 Urine Formation in the Nephron Loopof Henle 1 Filtration 3 TubularSecretion 2 TubularReabsorption 4 Concentration

20. Chapter 30 b. Urine formation in the nephron • 1) Tubular reabsorption • in the proximal tubule, most nutrients andwater are reabsorbed into the blood • 2) Tubular secretion • in the distal tubule additional wastes (H, K, NH3) and drugs are actively secreted into the tubule from the blood

21. Chapter 30 • c. Production and concentration of urine • in the collecting duct additional water may be secreted back into the blood, making the urine more concentrated and the blood less concentrated • the loop of Henle creates a concentration gradient through which the collecting duct passes • as the filtrate (urine) passes through the collecting duct it becomes the same concentration as the surrounding gradient (1200 mosm)milliosmolar

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24. Chapter 30 Related topics to urinary system • A. Hypertension • B. Urine testing • C. University life and "hyperdiuresis" • D. Dialysis and kidney transplantation

25. Chapter 30 Function-maintenance of homeostasis • a. Regulation of water content in the blood • In the case of dehydration, sensors in the brain stimulate the release of the hormone ADH (antidiuretic hormone also called vasopressin) • ADH is released from the pituitary • It passes through the blood to the kidneys where it stimulates the release of water back into the blood from the distal tubule and the collecting duct. • When water balance is normal, the ADH secretion is stopped.

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27. Chapter 30 Homeostasis in excretory system http://www.youtube.com/watch?v=WtrYotjYvtU http://www.youtube.com/watch?v=PQRtRA_R1ic http://www.youtube.com/watch?v=ROHOnPUu0aA

28. Chapter 30 • b. Regulation of levels of molecules in the blood • Penicillin, salicylates (aspirin) excreted • glucose, proteins, and amino acids are all reabsorbed. • phosphate, sulfate, lactate, vit. C all reabsorbed.

29. Chapter 30 • c. Maintenance of blood pH • Most important buffer system is bicarbonate ion (HCO3- ) • buffers maintain constant pH • kidney reabsorbs bicarbonate when blood is acidic and produces bicarbonate to further buffer the blood.

30. Chapter 30 • d. Regulation of blood pressure and oxygen content • when blood pressure falls, kidneys release renin into the blood. This causes formation of angiotensin. • angiotensin causes arterioles to constrict increasing blood pressure. Constriction also causes less blood to be filtered, maintaining water balance and further increasing blood pressure. • for low oxygen levels, kidneys release erythropoietin, stimulating red blood cell growth

31. Chapter 30 Cross Section of a Kidney RenalPelvis RenalCortex RenalArtery Nephron RenalMedulla RenalVein RenalPelvis Ureter

32. Chapter 30 Regulation of Water in Blood • Sensors in hypothalamus gauge osmotic concentration • Deviations cause posterior pituitary to turn ADH release on or off • ADH restores blood osmotic concentration • Red = increased osmotic concentration • Green = decreased osmotic concentration 1 5 2 3 4

33. Chapter 30 The End