Adam, Amy, Karl, Karlene , and Yifan

1. Excretory System Adam, Amy, Karl, Karlene, and Yifan

2. Introduction • http://www.youtube.com/watch?v=guOqyi5lUQQ (1:46-4:36) • Regulates bodily fluids, excreting and recycling waste • Main organs: kidneys, ureters, bladder and urethra • Disorders of the excretory system

3. Excretion • After metabolic activities (energy release, maintenance, repair) results in waste • Separating the needed and the unneeded or no longer needed • Skin, respiratory system, digestive system, excretory system

4. Overall Major Functions

5. Functions: Excretion of Metabolic Waste • The average person urinates 3000 a year • Bladder can hold 16-24 ounces of urine • Nitrogenous waste • Urea makes up the majority of this waste

6. Functions: Maintenance of Water-Salt Balance • Maintain balance with water and salt in blood • Regulating blood pressure • Balance between potassium, bicarbonate and calcium • Cells need to stay in an isotonic solution

7. Functions: Maintenance of Acid-Base Balance • Buffer for blood • Blood pH: 7.4 • Urine is usually a pH of 6 • Maintenance of alkaline reserve

8. Functions: Secretion of Hormones • Aids endocrine system in hormonal secretion • Calcitriol: Promotes calcium absorption • Erythropoiten: Production of red blood cells • Renin

9. Major Organs

10. Organs • Kidneys: Lower back, filters waste from blood, functions named above • Ureter: Muscular tubes that carry urine • Urinary Bladder: Urine is stored • Urethra: Tube that urine is secreted from

12. Kidney: Introduction

13. Kidney: Pathway Nephron

14. Kidney: Pathway • Filter • Tubule • Duct

15. Kidney: Filter • Renal artery enters Bowman’s capsule; glomerulus • Walls of glomerulus are impermeable to large molecules • pressurized blood aids filtration • Small molecules are permeable • The result is known as filtrate

16. Kidney: Tubule • Bowman’s capsule is connected to a looped tubule • Divided into three parts • Proximal convoluted tubule • Loop of Henle • Distal convoluted tubule • Used by each nephron for reabsorption

17. Kidney: Tubule • Proximal convoluted tubule • Uses ATP for active transport • Drives sodium ions, glucose, and other solutes back into the blood • Water follows these substances into the blood by osmosis

18. Kidney: Tubule • Loop of Henle

19. Kidney: Tubule • Loop of Henle • Descending limb extends from within the renal cortex into the renal medulla; extremely salty • Permeable to water; water flows back into blood • Ascending limb is impermeable to water and slightly permeable to solutes • Na+diffuses out of the tubule and into nearby blood vessels

20. Kidney: Tubule • In the thick-walled section, more Na+is removed by active transport (uses ATP) • Replenishes medulla’s salt • Makes the filtrate less concentrated than surrounding cortex tissue

21. Kidney: Tubule Medulla is salty Increases osmolarity for future filtrate Reabsorption of water causes salt concentration to decrease ATP is used to actively reabsorb sodium ions

22. Kidney: Tubule • Loop of Henle

23. Kidney: Tubule • Distal convoluted tubule • Active reabsorption depends on the needs of the body (sodium ions) • Passive reabsorption of negative ions occurs by electrical attraction (chloride) • Potassium ions and hydrogen ions are actively secreted by the body

24. Kidney: Duct • Tubule empties into a large pipe-like channel called a collecting duct • Lowers back into the medulla; reabsorbs water • The size of the pores depends on signals from the brain • The result can now be called urine • Reabsorbed substances are returned to the body

25. The roles of ADH and aldosterone in regulating water balance

26. Water Balance: Pituitary Gland • The pituitary gland is a gland at the base of the brain that sends signals to other glands and organs such as the thyroid gland, adrenal glands, ovaries, and testes • Directs them to produce certain hormones • Produces LD, ADH, FSH, and growth hormones

27. Water Balance: The Brain

28. Water Balance: Aldosterone • Aldosterone is a hormone that is produced by the adrenalglands • It works primarily on kidney (renal) cells to help maintain the balance of fluids and electrolytes in our bodies • It mainly works to control reabsorption of sodium and chloride and secretion of potassium and hydrogen

29. Water Balance: Aldosterone • Pathway: • The role of aldosterone in sodium and water balance is to regulate fluid and electrolyte balance • When sodium and plasma volume is decreased, it triggers the synthesis and secretion of aldosterone • When sodium and plasma volume return to normal levels, aldosterone secretion is reduced

30. Water Balance: Adrenal Gland

31. Water Balance: ADH • A hormone produced in the hypothalamus and secreted by the posterior pituitary gland • ADH stimulates reabsorption of water through the distal tubules and collecting ducts of the kidney, resulting in less water being excreted in the urine, thus conserving water

32. Water Balance: ADH • Pathway: • Part of the brain, the hypothalamus, detects that there is not enough water in the blood. The hypothalamus sends a message to the pituitary gland, which releases ADH. ADH travels from brain to the kidney and causes the kidneys to absorb more water and concentrate the urine. A lack of ADH results in increased urine volume and increased urination, a condition called diabetes insipidis.

33. Water Balance: ADH • ADH: antidiuretic hormone • Pathway: • Part of the brain, the hypothalamus, detects that there is not enough water in the blood • The hypothalamus sends a message to the pituitary gland, which releases ADH • ADH travels from brain to the kidney and causes the kidneys to absorb more water and concentrate the urine • A lack of ADH results in increased urine volume and increased urination, a condition called diabetes insipidis.

34. Water Balance: Deficit

35. Water Balance: Surplus

36. Water Balance: End of Cycle

37. Regulation of Blood pH Maintaining Blood pH in the Excretory System

38. Blood pH: Introduction • The normal pH of blood is around 7.4 • Allows our enzymes to function optimally • Failing to maintain homeostasis causes our blood pH to either increase or decrease • This increase/decrease can result in serious medical condition

39. Blood pH: Introduction • One way our blood pH can change in based on the foods/liquids we consume • Blood pH can also changed from metabolic processes • Three main homeostatic mechanisms used to maintain blood pH • Acid-Base Buffer System • Respiratory Centre • Kidney Function

40. Blood pH: Acid-Base Buffer • Buffers blood; prevents changes in pH • Takes up extra H+ ions of extra OH- ions that enter the blood • One of the most important buffer system involves the use of carbonic acid and bicarbonate ions

41. Blood pH: Acid-Base Buffer • The system reacts differently depending on the presence of extra hydrogen ions of extra hydroxide ions • If H+is added, the reaction that occurs is: • H+ + HCO3- H2C03 • When OH- ions are added to blood: • OH- + H2CO3 HCO3- + H2O

42. Blood pH: Acid-Base Buffer • In the first reaction, the bicarbonate ion takes up excess hydrogen ion, in order to form carbonic acid • In the second reaction, water is produced • Water will help maintain the blood pH, since water is neutral • These reactions temporarily prevent major changes in pH

43. Blood pH: Respiratory Centre • The hydrogen ion concentration is raised, the respiratory centre(in the medulla oblongata) increases breathing rate • It does this through specific signals that ensure our breathing muscles contract and relax regularly • Doing this causes the body to get rid of hydrogen ions • H+ + HCO3- H2CO3 H2O + CO2

44. Blood pH: Respiratory Centre • When the reaction moves from carbon dioxide to hydrogen, the blood pH decreases and increases the other way • Increasing breathing causes carbon dioxide to be generated more quickly, decreasing the number of hydrogen ions • It is vital to have the correct proportion of carbonic acid to bicarbonate ions in blood • Breathing causes a readjustment so the proportion is correct so H+ and OH- can continue to be absorbed

45. Blood pH: Kidneys • The first two mechanisms are aided by powerful actions of the kidneys • Only the kidneys are able to rid the body of a vast range of acidic and basic substances • Kidneys are slower acting, but have a more powerful effect • It is possible to urinate the excess acidic H+ ions or basic HCO3-ions in order to raise or lower blood pH

46. Blood pH: Kidneys • Imagine the kidneys as releasing H+ and reabsorbing HCO3- in order to maintain homeostasis • If blood is too acidic, H+ is released and HCO3- is absorbed • However, if blood is basic, neither is used • Another way of buffering is by using ammonia • Removes hydrogen ions and adds in bicarbonate ions • NH3 + H+ NH4+

47. Blood pH: Kidneys • Ammonia is produced in the tubule cells through the breakdown of amino acids • Ammonia works to produce ammonium ions • For every ammonium ion that is produced, a new HCO3− is made

48. Blood pH: Summary • There are three mechanisms used to maintain homeostasis, in terms of blood pH • Acid-Base Buffer System • Respiratory Centre • Kidney Function • Each one has a unique way of doing so • All three have advantages and disadvantages that go along with them

49. Dialysis: Introduction • What is dialysis? • Procedure that removes wastes and excess fluid from the blood when kidney function is lost due to renal failure • Why is dialysis needed? • Hyperkalemia • High potassium • Hyperphosphatemia • High phosphate • Uremia • Edema

50. Dialysis: Two Types