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  1. 1. Excretion
  2. 2. #1. Excretion <ul><li>Excretion-the process of removing metabolic wastes </li></ul><ul><li>-Without excretion toxic wastes would continue to circulate throughout the body </li></ul><ul><li>B. Metabolism –all chemical reactions that occur in our bodies </li></ul><ul><li>-produces useful products and waste products </li></ul>
  3. 3. <ul><li>C. Examples of wastes </li></ul><ul><li>1. Nitrogenous wastes in urine </li></ul><ul><li>2. carbon dioxide from lungs </li></ul><ul><li>3. Oxygen is excreted from plant via the stomata (daytime only) </li></ul>#1. Excretion
  4. 4. #2. Nitrogenous wastes and animal habitats <ul><li>Nitrogenous wastes </li></ul><ul><ul><li>Produced when amino acids are broken down to be used for energy </li></ul></ul><ul><ul><li>Produce ammonia, which is extremely basic and toxic </li></ul></ul><ul><li>Freshwater organisms (fish) </li></ul><ul><ul><li>Take in surplus of water </li></ul></ul><ul><ul><li>Excess water provides a medium for ammonia to be diluted and flushed out with the excess water </li></ul></ul>
  5. 5. <ul><li>C. Marine mammals </li></ul><ul><li>1. Do not take in excess water </li></ul><ul><li>2. Must convert ammonia to a less toxic substance </li></ul><ul><li>3. They convert ammonia to urea and trimethyline oxide </li></ul>#2. Nitrogenous wastes and animal habitats
  6. 6. <ul><li>D. Adult amphibians </li></ul><ul><li>1. conserve water and convert ammonia into urea </li></ul><ul><li>E. Birds </li></ul><ul><li>1. Birds cannot carry excess water for dilution of ammonia </li></ul><ul><li>2. Convert ammonia into insoluble uric acid (the white stuff in bird feces) </li></ul>#2. Nitrogenous wastes and animal habitats
  7. 7. <ul><li>F. Mammals </li></ul><ul><li>1. excrete urea (produced in the liver) </li></ul><ul><li>2. Urea is produced from ammonia by the ornithine cycle (the urea cycle) </li></ul><ul><li>3. </li></ul>#2. Nitrogenous wastes and animal habitats
  8. 8. 100,000 times less toxic than ammonia
  9. 10. #3. The Excretory System (an overview) <ul><li>Filtration-separation of products from body fluids </li></ul><ul><li>Reabsorption-return of useful products to the body </li></ul><ul><li>Secretion-solutes (wastes) are removed from the body and added to the filtrate </li></ul><ul><li>Excretion-discarding of waste products </li></ul><ul><li>**Accumulation of wastes (no excretion) could lead to death because toxins build up in the body </li></ul><ul><li>(Remember PKU?) </li></ul>
  10. 11. #4. The Human Kidney <ul><li>Kidney structure </li></ul><ul><li>1. humans have two kidneys </li></ul><ul><li>2. each has a renal artery leading to it </li></ul><ul><li>3. each has a renal vein and ureter leading away from it </li></ul><ul><li>4. renal vein takes away clean blood </li></ul><ul><li>5. the ureter leads urine to the bladder </li></ul>
  11. 12. <ul><li>Kidney structure- </li></ul><ul><li>6. Inside the kidney there are two regions </li></ul><ul><li>a. renal cortex-outer </li></ul><ul><li>b. renal medulla-inner </li></ul><ul><li>*The cortex and medulla are packed with nephrons </li></ul><ul><li>7. Nephrons –functional units of the kidneys </li></ul><ul><li>B. Animation </li></ul>#4. The Human Kidney
  12. 13. <ul><li>Kidneys from behind with spine removed </li></ul>
  13. 16. ASSIGNMENT <ul><li>1. Draw, label and annotate a diagram of the human kidney. Include the following: </li></ul><ul><li>cortex, medulla, pelvis, ureter and renal blood vessels </li></ul><ul><li>2. Draw, label and annotate a diagram of a nephron. Include the following: </li></ul><ul><li>glomerulus (bowman’s capsule, basement membrane, podocytes), renal artery (distinguish between afferent and efferent vessels), renal vein, distal tubule, proximal tubule, loop of Henle, collecting duct </li></ul>
  14. 17. <ul><li>Jobs of the nephron – ultrafiltration, reabsorption, secretion </li></ul><ul><li>Ultrafiltration-part of fluid from the blood is pushed into the nephrons and filtered </li></ul><ul><li>Reabsorption-molecules that the body ‘wants’ to keep, such as, glucose are reabsorbed into the blood </li></ul><ul><li>Secretion-undesired substances are released into the filtrate by the nephrons </li></ul>#4. The Nephron
  15. 19. <ul><li>E. There are about 1,000,000 nephrons per kidney and about 80km of tubules </li></ul><ul><li>F. Every nephron has a glomerulus, a Bowman’s capsule, a proximal tube, a loop of Henle and a distal tube </li></ul>#4. The Nephron
  16. 20. #5. Blood flow in the nephron <ul><li>Blood enters kidneys through renal artery </li></ul><ul><li>Renal artery splits into smaller vessels </li></ul><ul><ul><li>Afferent vessels </li></ul></ul><ul><ul><li>Efferent vessels </li></ul></ul><ul><li>Afferent vessels-carry blood to the glomerulus </li></ul><ul><li>Efferent vessels carry blood to other parts of the nephron </li></ul>
  17. 21. <ul><li>E. Glomerulus-ball of capillaries in the nephron </li></ul><ul><li>-surrounded by Bowman’s capsule </li></ul><ul><li>-where the proximal tube ends </li></ul>#5. Blood flow in the nephron
  18. 22. Glomerulus and Bowman’s capsule
  19. 23. <ul><li>F. Ultrafiltration </li></ul><ul><li>1. Blood pressure in the glomerulus forces water, salt, urea and other minerals into Bowman’s capsule </li></ul><ul><li>2. The filtrate must pass through a layer of three barriers to get there </li></ul><ul><li>a. wall of glomerulus (endothelial cells) </li></ul><ul><li>b. basement membrane of the glomerulus </li></ul><ul><li>c. podocytes </li></ul>#5. Blood flow in the nephron
  20. 24. <ul><li>3. Wall of the glomerulus (endothelium) is fenestrated </li></ul><ul><li>-it has small pores that allow blood plasma to pass through </li></ul>#5. Blood flow in the nephron
  21. 25. <ul><li>F. Ultrafiltration </li></ul><ul><li>4. Basement membrane-a protein membrane outside of the cells </li></ul><ul><li>-has no pores </li></ul><ul><li>-acts as a dialysis membrane by stopping large molecules from entering the Bowman’s capsule </li></ul>#5. Blood flow in the nephron
  22. 26. <ul><li>F. Ultrafiltration </li></ul><ul><li>5. Bowman’s capsule (inner wall) </li></ul><ul><ul><li>-made of podocytes </li></ul></ul><ul><ul><li>-podocytes have: </li></ul></ul><ul><ul><ul><ul><li>-many extensions which fold around blood vessels </li></ul></ul></ul></ul><ul><ul><ul><ul><li>-networks of filtration slits to hold back blood cells </li></ul></ul></ul></ul><ul><li> -fluid produced by ultrafiltration is collected by Bowman’s capsule </li></ul><ul><li> -from there it flows to the proximal tubule </li></ul>#5. Blood flow in the nephron
  23. 27. The Glomerulus
  24. 28. <ul><li>Glomerulus and podocytes </li></ul>
  25. 29. <ul><li>G. Osmoregulation </li></ul><ul><li>1. The control of water balance in blood, tissue and cytoplasm of cells in living organism </li></ul><ul><li>2. An internal adjustment </li></ul>#6. Filtrate flow in the nephron
  26. 30. <ul><li>H. Reabsorption </li></ul><ul><li>1. After ultrafiltration the filtrate leaves Bowman’s capsule and enters the proximal convoluted tubule where most reabsorption occurs </li></ul><ul><li>2. The fluid is made of glucose, amino acids, vitamins, hormones, urea, salt ions and water </li></ul><ul><li>3. most of the fluid is reabsorbed into the blood </li></ul>#6. Filtrate flow in the nephron
  27. 31. <ul><li>I. Reabsorption and the structure of proximal convoluted tubule </li></ul>#6. Filtrate flow in the nephron Orange arrow - Distal tubule Blue arrow - Proximal tubule Proximal tubule -invaginated outer membrane -has microvilli (brush border) -large lumen that carries filtrate -basement membrane
  28. 33. <ul><li>J. Reabsorption in the proximal tubule </li></ul><ul><li>1. Water is reabsorbed by osmosis </li></ul><ul><li>2. Sodium and glucose are reabsorbed via active transport </li></ul><ul><li>3. Chlorine passively follows the sodium ion </li></ul><ul><li>4. To facilitate the movement, the lumen wall is lined with microvilli </li></ul><ul><li>5. Microvilli increase the surface area </li></ul><ul><li>6. Mitochondria are present in these cells to facilitate active transport </li></ul>#6. Filtrate flow in the nephron
  29. 34. <ul><li>K. Loop of Henle-creates an area of high solute concentration in the cells and tissue fluid of the medulla </li></ul><ul><li>-found in medulla </li></ul><ul><li>-descending and ascending limbs are opposite in permeability </li></ul><ul><li>1. Descending loop of Henle </li></ul><ul><li>-water leaves the nephron via osmosis </li></ul><ul><li>-the descending limb is permeable to water but not salt </li></ul><ul><li>-NaCl becomes more concentrated </li></ul>#6. Filtrate flow in the nephron
  30. 35. <ul><li>K. Loop of Henle </li></ul><ul><li>2. Ascending loop of Henle </li></ul><ul><li>-made of two segments (thick and thin) </li></ul><ul><li>-both segments are impermeable to water </li></ul><ul><li>-the thin section permeable to NaCl </li></ul><ul><li>-NaCl diffuses out of the limb and into the interstitial fluid causing high osmolarity </li></ul>#6. Filtrate flow in the nephron
  31. 36. <ul><li>K. Loop of Henle </li></ul><ul><li>2. Ascending loop of Henle </li></ul><ul><li>-Thick segment continues the transfer of NaCl, but through active transport </li></ul><ul><li>-Salt removed from Henle’s loop helps maintain a concentration gradient in the medulla </li></ul>#5. Blood flow in the nephron
  32. 37. <ul><li>L. Vasa recta -blood vessels running along Henle’s loop </li></ul><ul><li>-maintains the concentration gradient of the medulla by countercurrent exchange </li></ul><ul><li>-countercurrent exchange-the path of the vasa recta and the loop of Henle flow opposite of each other </li></ul><ul><li>-there is no direct exchange of fluids between the filtrate and the blood </li></ul>#5. Blood flow in the nephron
  33. 38. <ul><li>L. Vasa recta </li></ul><ul><li>-Substances pass through the interstitial fluid of the medulla </li></ul><ul><li>-Blood entering the medulla will lose water to the region via osmosis and absorb salt and urea via diffusion </li></ul><ul><li>(in the descending capillary of the vasa recta) </li></ul>#5. Blood flow in the nephron
  34. 39. <ul><li>L. Vasa recta </li></ul><ul><li>-the opposite happens in the ascending capillary of the vasa recta </li></ul><ul><li>-movement of fluid requires no energy because it happens via diffusion and osmosis </li></ul>#6. Filtrate flow in the nephron
  35. 40. <ul><li>M. Distal tubule </li></ul><ul><li>-regulates potassium and salt concentration of body fluids by varying the amount of potassium secreted into the filtrate and the amount of salt absorbed from the filtrate </li></ul><ul><li>-ions are exchanged between blood and filtrate to maintain concentration gradients </li></ul>#6. Filtrate flow in the nephron
  36. 41. <ul><li>N. Collecting duct </li></ul><ul><li>-epithelium of collecting duct is permeable to water but not salt </li></ul><ul><li>-duct carries filtrate back towards medulla and renal pelvis </li></ul><ul><li>-as the filtrate moves along water is lost and the filtrate becomes more concentrated </li></ul><ul><li>-the bottom of the collecting duct is permeable to urea </li></ul>#5. Blood flow in the nephron
  37. 42. <ul><li>N. Collecting duct </li></ul><ul><li>-some of the urea diffuses into the interstitial fluid in the medulla </li></ul><ul><li>-causes high osmolarity of the medulla </li></ul><ul><li>-high osmolarity of the interstitial fluid allows the kidney to conserve water by excreting urine that is hyperosmotic to the general body fluids </li></ul>#5. Blood flow in the nephron
  38. 43. <ul><li>***Collecting duct and the loop of Henle maintain the osmolarity in the interstitial tissue of the kidney </li></ul><ul><li>-this makes it possible to concentrate the urine </li></ul><ul><li>***After the collecting duct the filtrate moves to the: </li></ul><ul><li>renal pelvis ->ureters->bladder->urethra </li></ul>#5. Blood flow in the nephron
  39. 44. <ul><li>Renal artery </li></ul><ul><li>Glomerulus </li></ul><ul><ul><li>(epithelium, basement membrane, podocytes) </li></ul></ul><ul><li>Bowman’s capsule </li></ul><ul><li>Proximal tubule </li></ul><ul><li>Descending loop of Henle (water leaves through osmosis/salt becomes more concentrated) </li></ul>#7. Filtrate in the nephron (quick review)
  40. 45. <ul><li>Ascending loop of Henle </li></ul><ul><ul><li>Thin-impermeable to water/permeable to salt/salt diffuses out </li></ul></ul><ul><ul><li>Thick-impermeable to water/permeable to salt/salt moves out through active transport </li></ul></ul><ul><li>Vasa recta-blood vessels along loop of Henle </li></ul><ul><ul><li>Uses countercurrent exchange to maintain concentration gradient in the medulla </li></ul></ul><ul><li>Distal tubule </li></ul>#5. Blood flow in the nephron (quick review)
  41. 46. <ul><li>9. Collecting duct (permeable to water but impermeable to salt) </li></ul><ul><li>a. water diffuses out through osmosis </li></ul><ul><li>b. salt stays and makes urine more concentrated </li></ul><ul><li>c. some urea diffuses out (causes high osmolarity of interstitial fluid which increases the amount of osmosis which makes urine hyperosmotic to body fluids) </li></ul>#7. Filtrate in the nephron (quick review)
  42. 47. Assignment Due Tomorrow <ul><li>Get a red book. </li></ul><ul><li>Outline negative feedback in regards to ADH and osmoregulation. </li></ul><ul><li>If you wish . . . </li></ul><ul><li>a. the first two people may present their outlines and receive 5 points of E.C. </li></ul><ul><li>b. the presentations must be accurate and detailed </li></ul><ul><li>c. the class should be able to take notes from your work </li></ul><ul><li>d. you have to put your outline on transparencies or PowerPoint </li></ul>
  43. 48. #8. Blood Composition of Renal Artery and Renal Vein <ul><li>Renal artery </li></ul><ul><li>1. oxygen rich </li></ul><ul><li>2. contains more urea, salt and water than the set value </li></ul><ul><li>B. Renal vein </li></ul><ul><li>1. oxygen poor </li></ul><ul><li>2. contains correct amount of water and salts and very little urea </li></ul>
  44. 49. <ul><li>Glomerular filtrate </li></ul><ul><ul><li>No proteins </li></ul></ul><ul><ul><li>Contains glucose, sodium and small amounts of urea </li></ul></ul><ul><li>Urine </li></ul><ul><ul><li>Has no proteins and no glucose </li></ul></ul><ul><ul><li>Has large amounts of urea and sodium </li></ul></ul>#9. Blood Composition of Glomerular Filtrate and Urine
  45. 50. Contents of Fluids in the Kidney <ul><li>Units=mg per 100 ml of blood </li></ul>900 1200 720 900 Sodium ions 0 0 740 740 Proteins 30 2000 24 30 Urea 90 0 90 90 Glucose Glomerular filtrate Urine Renal vein Renal artery
  46. 51. #10. Kidney failure and dialysis <ul><li>If the kidneys fail, waste cannot be removed from the body </li></ul><ul><li>There are two main types of kidney failure </li></ul><ul><ul><li>Acute-rapid onset </li></ul></ul><ul><ul><li>Chronic-long duration/slow progress </li></ul></ul><ul><li>If the kidneys fail, a person will become dependent on a dialysis machine </li></ul>
  47. 52. #11. Dialysis Machines <ul><li>The concept: lead patients blood through a machine that will clean it and return it to the body </li></ul><ul><li>Dialysis involves the diffusion of solutes from a high to low concentration through a semi-permeable membrane </li></ul><ul><li>The dialysis membrane used in the machines is usually made of cellulose acetate or cellulose nitrate (the membrane acts as a filter) </li></ul>
  48. 53. <ul><li>D. The filter has small pores that allow small solute particles through (blood and large proteins cannot fit through) </li></ul><ul><li>Blood flows on one side of the dialysis membrane and dialysis fluid flows on the other </li></ul><ul><li>The dialysis fluid contains solute concentrations in found in healthy blood </li></ul>#11. Dialysis Machines
  49. 54. <ul><li>G. The dialysis fluid contains no urea or other excretory fluids </li></ul><ul><li>-these diffuse from the patients blood into the dialysis fluid </li></ul><ul><li>H. Glucose and other desired substances found in the dialysis fluid do not diffuse into the blood </li></ul><ul><li>Dialysis fluid contains dextran </li></ul><ul><ul><li>-Excess water is removed by osmosis from the blood to the dialysis fluid to neutralize it </li></ul></ul>#11. Dialysis Machines
  50. 55. <ul><li>J. During dialysis blood flow through tubes and between sheets of dialysis membrane </li></ul><ul><li>K. Blood is taken and returned via needles in the person’s arm </li></ul><ul><li>The dialysis fluid is continuously replaced during a session to maintain a continuous concentration gradient </li></ul><ul><li>Most patients spend about 4 hours, 3 times a week in dialysis treatment </li></ul>#11. Dialysis Machines
  51. 56. <ul><li>1. ADH animation 1 </li></ul><ul><li>Dialysis animation 2 </li></ul><ul><li>Dialysis animation 3 </li></ul>
  52. 57. #12. Acute renal failure <ul><li>Caused by serious illness or operation which can reduce the amount of blood flow to the kidneys </li></ul><ul><li>Blood flow to the kidneys can be reduced by: </li></ul><ul><ul><li>-blood loss </li></ul></ul><ul><ul><li>-decrease in blood pressure </li></ul></ul><ul><ul><li>-severe dehydration </li></ul></ul><ul><ul><li>-lack of salt </li></ul></ul><ul><li>C. Acute kidney damage can also be caused as a side effect to medication </li></ul><ul><li>D. The cause is treated and the kidneys will often return to normal </li></ul><ul><li>(dialysis may be necessary until full function is restored) </li></ul>
  53. 58. #13. Chronic renal failure <ul><li>Can be caused by: </li></ul><ul><ul><li>-inflammatory conditions of the kidney tissue </li></ul></ul><ul><ul><li>(a complication of type I diabetes) </li></ul></ul><ul><li>-chronic blockage to the drainage of the kidney </li></ul><ul><li>-inheritance </li></ul><ul><li>B. Often the cause cannot be identified because it occurred so long ago </li></ul><ul><li>C. Chronic failure is often irreversible </li></ul><ul><li>D. Often requires a dialysis machinefrcx </li></ul>
  54. 59. <ul><li>p. 239 #1, 3, 4 </li></ul><ul><li>Due at the end of class. </li></ul>