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33 Lecture Ppt

  1. 1. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 33 Osmoregulation and Excretion
  2. 2. Metabolic Waste Products Have Different Advantages 33-
  3. 3. 33.1 The nitrogenous waste product of animals varies according to the environment <ul><li>Ammonia - Amino groups removed from amino acids immediately form ammonia (NH 3 ) by the addition of a third hydrogen ion </li></ul><ul><ul><li>Toxic and can be an excretory product if a good deal of water is available to wash it from the body </li></ul></ul><ul><li>Urea - production requires the expenditure of energy because it is produced in the liver by a set of energy-requiring enzymatic reactions </li></ul><ul><ul><li>Less toxic than ammonia and can be excreted in a moderately concentrated solution, conserving water </li></ul></ul><ul><li>Uric Acid - synthesized by a series of enzymatic reactions that requires expenditure of even more ATP than urea </li></ul><ul><ul><li>Uric acid is routinely excreted by insects, reptiles, and birds </li></ul></ul>33-
  4. 4. Figure 33.1 Excretion of –NH 2 33-
  5. 5. 33.2 Many invertebrates have organs of excretion <ul><li>Planarians - flatworms that live in fresh water and have two strands of branching excretory tubules that open to the outside of the body through excretory pores </li></ul><ul><ul><li>Along tubules are bulblike flame cells </li></ul></ul><ul><li>Earthworms - annelids, the body is divided into segments, and nearly every body segment has a pair of excretory structures called nephridia </li></ul><ul><ul><li>Each nephridium is a tubule with a ciliated opening and an excretory pore </li></ul></ul><ul><li>Arthropods - Insects have a unique excretory system consisting of long, thin Malpighian tubules attached to the gut </li></ul><ul><ul><li>Uric acid is actively transported from the surrounding hemolymph into these tubules, and water follows a salt gradient established by active transport of K + </li></ul></ul>33-
  6. 6. Figure 33.2 Excretory organs in invertebrates 33-
  7. 7. Osmoregulation Varies According to the Environment 33-
  8. 8. 33.3 Aquatic vertebrates have adaptations to maintain the water-salt balance of their bodies <ul><li>Cartilaginous Fishes </li></ul><ul><ul><li>Total concentration of ions in their blood is less than that in sea water </li></ul></ul><ul><ul><ul><li>Blood plasma is nearly isotonic to sea water because they pump it full of urea, giving their blood the same tonicity as sea water </li></ul></ul></ul><ul><li>Marine Bony Fishes </li></ul><ul><ul><li>Marine bony fishes lose water by osmosis at their gills </li></ul></ul><ul><ul><li>To counteract this, they drink sea water almost constantly </li></ul></ul><ul><ul><li>To rid the body of excess salt, they actively transport it into the surrounding sea water at the gills </li></ul></ul><ul><ul><li>The kidneys conserve water, and they produce a scant amount of isotonic urine </li></ul></ul><ul><li>Freshwater Bony Fishes </li></ul><ul><ul><li>Tend to gain water by osmosis across the gills and the body surface </li></ul></ul><ul><ul><li>As a consequence, these fishes never drink water and actively transport salts into the blood across the membranes of their gills </li></ul></ul><ul><ul><li>They eliminate excess water by producing large quantities of dilute (hypotonic) urine </li></ul></ul>33-
  9. 9. Figure 33.3A The blood sharks is isotonic to sea water 33-
  10. 10. Figure 33.3B Osmoregulation in marine bony fishes 33-
  11. 11. Figure 33.3C Osmoregulation in freshwater bony fishes 33-
  12. 12. 33.4 Terrestrial vertebrates have adaptations to maintain the water-salt balance of their bodies <ul><li>Kangaroo Rat </li></ul><ul><ul><li>Lives in the desert and fur prevents loss of water to the air, and during the day, it remains in a cool burrow </li></ul></ul><ul><ul><li>Rat’s nasal passage has a highly convoluted mucous membrane surface that captures condensed water from exhaled air </li></ul></ul><ul><li>Seagulls, Reptiles, and Mammals </li></ul><ul><ul><li>In birds, salt-excreting glands located near the eyes produce a salty solution that is excreted through the nostrils and moves down grooves on their beaks until it drips off </li></ul></ul><ul><ul><li>In marine turtles, the salt gland is a modified tear (lacrimal) gland, and in sea snakes, a salivary sublingual gland beneath the tongue gets rid of excess salt </li></ul></ul><ul><ul><li>If humans drink sea water, we lose more water than we take in just ridding the body of all that salt </li></ul></ul>33-
  13. 13. Figure 33.4A Adaptations of a kangaroo rat to minimize water loss 33-
  14. 14. Figure 33.4B Marine birds and reptiles are apt to have salt glands to pump excess salt 33-
  15. 15. The Kidney Is an Organ of Homeostasis 33-
  16. 16. 33.5 The kidneys are a part of the urinary system <ul><li>Urine made by the kidneys is conducted from the body by the other organs in the urinary system </li></ul><ul><ul><li>Each kidney is connected to a ureter , a duct that takes urine from the kidney to the urinary bladder where it is stored </li></ul></ul><ul><ul><li>It is voided from the body through the single urethra </li></ul></ul><ul><ul><ul><li>In males, urethra passes through the penis </li></ul></ul></ul><ul><ul><ul><li>In females, opening of the urethra is ventral to the vagina </li></ul></ul></ul><ul><li>Other Vertebrates </li></ul><ul><ul><li>In all vertebrates, except for placental mammals, a duct from the kidney conducts urine to a cloaca, a common depository for indigestible remains, urine, and sex cells </li></ul></ul>33-
  17. 17. Figure 33.5 The mammalian urinary system 33-
  18. 18. 33.6 The mammalian kidney contains many tubules <ul><li>Three major parts of a mammalian kidney </li></ul><ul><ul><li>Renal cortex - is the outer region of a kidney, with a granular appearance </li></ul></ul><ul><ul><li>Renal medulla - six to ten cone-shaped renal pyramids that lie inside the renal cortex </li></ul></ul><ul><ul><li>Renal pelvis - hollow chamber where urine collects before it is carried to the bladder </li></ul></ul>33-
  19. 19. Figure 33.6A Macroscopic ( left ) and microscopic anatomy of the kidney 33-
  20. 20. Nephrons <ul><li>Nephrons - tubules that produce urine in mammals </li></ul><ul><ul><li>Blind end of a nephron is pushed in on itself to form the glomerular capsule (Bowman capsule) </li></ul></ul><ul><ul><li>Proximal convoluted tubule leads from the glomerular capsule and lined by cells with many mitochondria and microvilli </li></ul></ul><ul><ul><li>Loop of the nephron (loop of Henle), which has a descending limb and an ascending limb </li></ul></ul><ul><ul><li>Distal convoluted tubule follows the loop of the nephron </li></ul></ul><ul><ul><li>Collecting ducts transport urine through renal medulla and deliver it to renal pelvis </li></ul></ul><ul><ul><li>Afferent arteriole, divides to form a capillary bed, the glomerulus where liquid exits and enters the glomerular capsule </li></ul></ul><ul><ul><li>Peritubular capillary network leads to venules that join to form the renal vein, a vessel that enters the inferior vena cava </li></ul></ul>33-
  21. 21. Figure 33.6B Nephron anatomy 33-
  22. 22. 33.7 Urine formation requires three steps <ul><li>Glomerular filtration </li></ul><ul><ul><li>Movement of small molecules across the glomerular wall into the glomerular capsule as a result of blood pressure </li></ul></ul><ul><ul><ul><li>Glomerular filtrate is protein-free, but otherwise it has the same composition as blood plasma </li></ul></ul></ul><ul><li>Tubular reabsorption </li></ul><ul><ul><li>Takes place when substances move across the walls of the tubules into the associated peritubular capillary network </li></ul></ul><ul><ul><li>Osmolarity of the blood is same as the filtrate within the glomerular capsule, so osmosis of water from the filtrate into the blood does not occur </li></ul></ul><ul><li>Tubular secretion - second way substances are removed from blood and added to tubular fluid </li></ul><ul><ul><li>Eliminates uric acid, hydrogen ions, ammonia, creatinine, histamine, and penicillin </li></ul></ul>33-
  23. 23. Figure 33.7 The process of urine formation 33-
  24. 24. APPLYING THE CONCEPTS—HOW BIOLOGY IMPACTS OUR LIVES 33.8 Urinalysis can detect drug use <ul><li>As early as 600 B.C., Hindu physicians in India noted that the urine of a diabetic was sweet to the taste </li></ul><ul><ul><li>In diabetes mellitus, blood glucose is abnormally high </li></ul></ul><ul><ul><ul><li>Insulin-secreting cells have been destroyed </li></ul></ul></ul><ul><ul><ul><li>Cell receptors do not respond to insulin present </li></ul></ul></ul><ul><li>Urinalysis is used for diagnosis of drug use </li></ul><ul><ul><li>Detects breakdown products of drugs that have been consumed or injected </li></ul></ul><ul><ul><li>Two techniques can detect metabolites </li></ul></ul><ul><ul><ul><li>Test strip contains monoclonal antibodies specific for metabolites of street drugs </li></ul></ul></ul><ul><ul><ul><li>More sophisticated chemical analysis, such as gas chromatography </li></ul></ul></ul><ul><ul><li>Tracking long-term drug use may require using hair samples in addition to urine samples </li></ul></ul>33-
  25. 25. 33.9 The kidneys concentrate urine to maintain water-salt balance <ul><li>Kidneys regulate the water-salt balance of the blood, and also maintain the blood volume and blood pressure </li></ul><ul><ul><li>Most of the water and salt (NaCl) present in the filtrate is reabsorbed across the wall of the proximal convoluted tubule </li></ul></ul><ul><ul><li>Salt diffuses out of lower portion of the ascending limb of the nephron loop </li></ul></ul><ul><ul><ul><li>Upper, thick portion of the limb actively extrudes NaCl into the tissue of the outer renal medulla </li></ul></ul></ul><ul><ul><li>Urea is believed to leak from the lower portion of the collecting duct </li></ul></ul><ul><ul><li>As water diffuses out of descending limb, the remaining fluid within the limb encounters an even greater osmotic concentration of solute </li></ul></ul><ul><ul><ul><li>Water will continue to leave descending limb from top to bottom </li></ul></ul></ul><ul><ul><li>Water diffuses out of the collecting duct into the renal medulla, and the urine within the collecting duct becomes hypertonic to blood plasma </li></ul></ul><ul><li>Antidiuretic hormone (ADH) released by the posterior lobe of the pituitary plays a role in water reabsorption at the collecting duct </li></ul>33-
  26. 26. Figure 33.9A Regulation of water-salt balance in mammals 33-
  27. 27. Hormones Control the Reabsorption of Salt <ul><li>Blood volume and pressure is, in part, regulated by salt reabsorption </li></ul><ul><ul><li>When blood volume and blood pressure is not sufficient to promote glomerular filtration the kidneys secrete renin, an enzyme that changes angiotensinogen into angiotensin I </li></ul></ul><ul><ul><li>Later, angiotensin I is converted into angiotensin II, a vasoconstrictor that causes blood pressure to increase </li></ul></ul><ul><li>Aldosterone promotes the excretion of potassium ions (K + ) and the reabsorption of sodium ions (Na + ) </li></ul><ul><ul><li>Reabsorption of sodium ions is followed by the reabsorption of water, and blood volume and pressure increase </li></ul></ul><ul><li>Atrial natriuretic hormone (ANH) - hormone secreted by the atria of the heart when cardiac cells are stretched due to increased blood volume </li></ul><ul><ul><li>Promotes excretion of Na + followed by excretion of water, and therefore blood volume and blood pressure decrease </li></ul></ul>33-
  28. 28. Figure 33.9B The renin-angiotensin-aldosterone system 33-
  29. 29. 33.10 Lungs and kidneys maintain acid-base balance <ul><li>Bicarbonate (HCO 3 − ) buffer system works together with the breathing process to maintain the pH of the blood </li></ul><ul><ul><li>Insert equation from left column of page 659 </li></ul></ul><ul><li>Excretion of carbon dioxide (CO 2 ) by the lung s helps keep the pH within normal limits </li></ul><ul><ul><li>When CO 2 is exhaled, hydrogen ions (H + ) are tied up in water </li></ul></ul><ul><li>Only the kidneys can rid the body of a wide range of acidic and basic substances </li></ul><ul><ul><li>Ammonia (NH 3 ) produced in tubule cells provides a means of buffering these hydrogen ions in urine </li></ul></ul><ul><li>Acidosis and Alkalosis </li></ul><ul><ul><li>Normal pH of arterial blood is around 7.4 </li></ul></ul><ul><ul><li>A person is said to have acidosis when the pH is below 7.34 and alkalosis when the pH is higher than 7.45 </li></ul></ul>33-
  30. 30. Figure 33.10 Excretion of these ions regulates pH 33-
  31. 31. APPLYING THE CONCEPTS—HOW SCIENCE PROGRESSES 33.11 The artificial kidney machine makes up for faulty kidneys <ul><li>After a person suffers kidney damage waste substances accumulate in the blood, a condition called uremia </li></ul><ul><li>Patients in renal failure most often seek a kidney transplant </li></ul><ul><ul><li>In the meantime they undergo hemodialysis utilizing an artificial kidney </li></ul></ul><ul><ul><li>Substances more concentrated in blood diffuse into the dialysis solution, and substances more concentrated in the dialysate diffuse into the blood </li></ul></ul><ul><ul><li>Artificial kidney either extracts substances from blood, including waste products or toxic chemicals and drugs, or adds a substance to the blood </li></ul></ul>33-
  32. 32. Figure 33.11 An artificial kidney machine 33-
  33. 33. APPLYING THE CONCEPTS—HOW BIOLOGY IMPACTS OUR LIVES 33.12 Dehydration and water intoxication occur in humans <ul><li>Dehydration - serious condition resulting from loss of water by cells </li></ul><ul><ul><li>Common cause of dehydration is excessive sweating, perhaps during exercise, without replacing any of the water lost </li></ul></ul><ul><ul><li>Can also be a side effect of an illness that causes prolonged vomiting or diarrhea </li></ul></ul><ul><li>Water intoxication - caused by a gain of water by cells </li></ul><ul><ul><li>Solute concentration in extracellular fluid decreases and water enters the cells </li></ul></ul><ul><ul><li>Marathoners who experience nausea and vomiting after a race are probably suffering from water intoxication, which can lead to pulmonary edema and swelling in the brain </li></ul></ul>33-
  34. 34. Connecting the Concepts: Chapter 33 <ul><li>Human kidney plays three important roles in homeostasis </li></ul><ul><ul><li>Excreting metabolic wastes </li></ul></ul><ul><ul><li>Maintaining water-salt balance (osmoregulation) </li></ul></ul><ul><ul><li>Maintaining acid-base balance of internal fluids </li></ul></ul><ul><li>Primary nitrogenous waste of humans is urea </li></ul><ul><ul><li>Kidneys are assisted to a limited degree by sweat glands in the skin, which excrete perspiration, a mixture of water, salt, and some urea </li></ul></ul><ul><li>If blood does not have normal water - salt balance, blood volume and blood pressure are affected </li></ul><ul><ul><li>Too low a concentration of Na + in the blood causes blood pressure to lower and activates the renin-angiotensin-aldosterone sequence </li></ul></ul><ul><ul><li>Then kidneys increase Na + reabsorption, which is followed by the reabsorption of water </li></ul></ul><ul><ul><li>Too high a concentration of Na + in the blood leads to the release of ADH from the posterior pituitary and the reabsorption of water </li></ul></ul><ul><li>Two mechanisms offset short-term challenges to the acid-base balance: the blood bicarbonate (HCO 3 − ) buffering system and the process of breathing </li></ul><ul><ul><li>Excretion of carbon dioxide by the lungs helps keep the blood pH within normal limits </li></ul></ul><ul><ul><li>Only the kidneys can rid the body of a wide range of acidic and basic substances </li></ul></ul>33-