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Chapter 25: Control of the Internal Environment

Chapter 25: Control of the Internal Environment. NEW AIM: How do organisms deal with metabolic waste?. I. Excretion. A. removal of metabolic waste. i. Carbon dioxide. ii. Nitrogenous waste. a. produced from breakdown of proteins and nucleic acids. iii. Water.

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Chapter 25: Control of the Internal Environment

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  1. Chapter 25: Control of the Internal Environment NEW AIM: How do organisms deal with metabolic waste? I. Excretion A. removal of metabolic waste i. Carbon dioxide ii. Nitrogenous waste a. produced from breakdown of proteins and nucleic acids iii. Water

  2. Chapter 25: Control of the Internal Environment NEW AIM: How do organisms deal with metabolic waste? b. Forms of nitrogenous waste 1. Ammonia (NH3) - highly toxic - highly water soluble Fig. 25.8 - formed by deamination of AAs - secreted by most aquatic animals - Must be secreted immediately or will denature proteins and cause death Land animals do not have the luxury of being able to secrete waste continuously due to water loss…how do we get around this? Adide: NH3 (ammonia) can get protonated to NH4+ (ammonium) in aqueous solution and vice versa. NH3< - - > NH4+ ; pKa = 9.23

  3. Chapter 25: Control of the Internal Environment NEW AIM: How do organisms deal with metabolic waste? b. Forms of nitrogenous waste 2. Urea - 100,000X less toxic than NH3 - Highly water soluble Fig. 25.8 - mammals, adult amphibians, sharks, some fish - convert NH3 to urea (occurs in liver – site of deamination) - urea travels in blood and is removed by kidneys - why don’t all organisms just make urea?? It is not free, costs ATP - certain toads switch back and forth depending if they are in water where they can get rid of NH3 quickly or on land.

  4. Chapter 25: Control of the Internal Environment NEW AIM: How do organisms deal with metabolic waste? b. Forms of nitrogenous waste 2. Urea - 100,000X less toxic than NH3 - Highly water soluble - mammals, adult amphibians, sharks, some fish - convert NH3 to urea (liver – site of deamination) - urea travels in blood and is removed by kidneys - why don’t all organisms just make urea?? It is not free, costs ATP You thought Krebs and Calvin were awesome, but what about THE UREA (ornithine) CYCLE… Formation of urea requires many enzymes (which take lots of ATP to make) and additional ATP to power endergonic reactions!! Aside: This was the first metabolic cycle discovered by…wait for it…Hans Krebs!!

  5. Chapter 25: Control of the Internal Environment NEW AIM: How do organisms deal with metabolic waste? b. Forms of nitrogenous waste 2. Urea Compare hypothetical storage of NH3 to storing urea in bladder. Fig. 25.8 Ammonia (NH3), cannot be stored at high concentration as it is too toxic and would destroy the bladder. Therefore, it must be gotten rid of immediately 1. If you live on land you would need to constantly be urinating to get rid of it and you would thus be constantly losing water…dehydration (on top of constantly urinating…). 2. If you live in water, you just let the ammonia diffuse across the epithelium into the water…

  6. Chapter 25: Control of the Internal Environment NEW AIM: How do organisms deal with metabolic waste? b. Forms of nitrogenous waste 2. Urea What about birds (no bladder) or many insects / reptiles that are highly susceptible to drying out – desiccation)? Fig. 25.8

  7. Chapter 25: Control of the Internal Environment NEW AIM: How do organisms deal with metabolic waste? b. Forms of nitrogenous waste 3. Uric acid - relatively non-toxic - Largely INSOLUBLE in water Fig. 25.8 - birds, insects, many reptiles, land snails, amphibians in deserts - secreted as a paste or dry powder - costs a lot of ATP to make - savings is in water - great for external development (egg) – why? Birds don’t urinate!

  8. Chapter 25: Control of the Internal Environment NEW AIM: How do organisms deal with metabolic waste? b. Forms of nitrogenous waste Summary Fig. 25.8

  9. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? II. Excretion in other organisms A. Protists - diffusion through membrane - ammonia and CO2 - Some use contractile vacuoles to remove water waste

  10. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? II. Excretion in other organisms B. Cnidaria (hydra) - entire body in contact with water - diffusion of ammonia and CO2 directly into surrounding water

  11. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? II. Excretion in other organisms C. Annelida (Earthworm) - Nephridia = excretory organs of Earthworm - one pair (2) in each segment - excrete urine (urea, ammonia, salts dissolved in water) out the nephridopores - CO2 excreted through skin (skin-breathers) Body fluid from one segment containing waste enters the funnel of the nephridia in the next segment. Capillaries surround the nephridia. Some of the solutes like salts, and water (the solvent of course) diffuse back into the blood (reabsorbed). The fluid, now mostly waste products like urea and ammonia dissolved in water, continues to the bladderlike storage organ and will then be excreted through the nephridopores. (nephridopores)

  12. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? II. Excretion in other organisms F. Arthropod (Grasshopper) - CO2 diffuses into tracheal tubes and expelled through spiracles - Malpighian tubules = excretory organs closely associated with the intestines that removes uric acid and excess salts from hemolymph and put it into the intestines… - excretes URIC ACID with fecal matter

  13. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? II. Excretion in other organisms Summary

  14. Chapter 25: Control of the Internal Environment NEW AIM: How do organisms deal with metabolic waste? III. Human Excretory System Fig. 25.9 In addition: *LIVER - makes urea from ammonia from deamination of amino acids **Skin (urea with sweat) and lungs (CO2) also involved in excretion

  15. Chapter 25: Control of the Internal Environment NEW AIM: How do organisms deal with metabolic waste? III. Human Excretory System A. Kidneys i. Site of urine formation ii. maintains the homeostatic balance of blood Fig. 25.9 1. Regulates metabolic waste • filters out metabolites (urea) 2. Regulates osmolarity - filters out minerals (salts) /water 3. Regulates blood pressure 4. Regulates pH iii. 1100-2000L of blood filtered per day

  16. Chapter 25: Control of the Internal Environment NEW AIM: How do organisms deal with metabolic waste? III. Human Excretory System B. Flow of the excretory system i. Blood enter via renal artery ii. Urea, water and salts extracted by nephrons of kidneys (filtrate) iii. Filtrate drains into renal pelvis (urine now) -> ureter -> bladder -> urethra -> toilet iv. Blood leaves via renal vein

  17. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? III. Human Excretory System C. How does the kidney extract filtrate? 1. The Nephron i. Functional unit of the kidney Fig. 25.9 ii. ~1,000,000 per kidney

  18. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? III. Human Excretory System C. How does the kidney extract filtrate? 1. The Nephron Fig. 25.9 i. Functional unit of the kidney (tiny filtering unit) ii. ~1,000,000 per kidney iii. Each extracts tiny amount of filtrate

  19. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? III. Human Excretory System C. How does the kidney extract filtrate? 1. The Nephron ** Fig. 25.9

  20. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? III. Human Excretory System C. How does the kidney extract filtrate? 1. The Nephron - Flow chart through nephron Fig. 25.9 http://www.biologymad.com/resources/kidney.swf

  21. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? III. Human Excretory System C. nephron Practice Labeling http://www.biologymad.com/resources/kidney.swf Fig. 25.9

  22. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? III. Human Excretory System C. nephron Urine is produced in 4 major processes Fig. 25.10 IMPORTANT: Water, urea, salts, monomers, toxins, etc… are forced out of the glomerulus capillaries by high blood pressure into Bowman’s capsule and enter the nephron tubule non-selectively. The only selective filter is the size of the molecule. Glucose and smaller enters automatically. The kidney can only control what is taken back (reabsorbed) into the blood, NOT what goes into Bowman’s and the nephron tubule!!

  23. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? III. Human Excretory System A closer look at urine formation C. nephron Fig. 25.11

  24. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? A diuretic is any drug that elevates the rate of urination. III. Human Excretory System D. Regulating the nephron (water reabsorption) i. Under hormonal control ii. The kidneys regulates blood osmolarity (solute concentration of blood) a. If blood is hypertonic, cells will lose water and crenate. b. If blood is hypotonic, cells will gain water and lyse. - The kidney must controls how much water is in the blood by removing it or not removing it from the nephron tubule… ****By default, monomers and smaller will enter Bowmans. The only selecive criteria is size!! The kidney cannot stop these molecules from entering!! Therefore it can only control what it takes back. If you are dehydrated, hypertonic, it will take back water. If your blood is hypotonic, they will NOT take back water. It is all about reabsorption.

  25. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? A diuretic is any drug that elevates the rate of urination. III. Human Excretory System D. Regulating the nephron (water reabsorption) i. Under hormonal control ii. The kidneys regulates blood osmolarity (solute concentration of blood) a. If blood is hypertonic, cells will lose water and crenate. b. If blood is hypotonic, cells will gain water and lyse. - The kidney must controls how much water is in the blood by removing it or not removing it from the nephron tubule… iii. Kidneys also regulate blood pressure (BP) - BP is controlled by controlling blood volume - Low blood volume = low BP, add water to blood - high blood volume = high BP, take water out of blood - Renin – angiotensin – aldosterone system Water reabsorption by the kidneys is contolled by AntiDiuretic Hormone (ADH), also called vasopressin Diuresis = urination

  26. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? III. Human Excretory System D. Regulating the nephron (water reabsorption) iv. How does ADH accomplish this? • Solute sensor cells are located in the hypothalamus of the brain • (ex. too little solute = too much water; BP to high = too much water) • What if you eat a lot of salty food (food high in sodium) and your blood volume increases because ADH is secreted and your kidneys are reabsorbing water from the nephron tubules to maintain the osmotic balance so your cells do not crenate? • Your blood pressure will be high and your kidneys really can’t do anything about it because if they remove water, the blood will become hypertonic relative to your cells…

  27. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? III. Human Excretory System D. Regulating the nephron (water reabsorption) iv. How does ADH accomplish this?

  28. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? III. Human Excretory System D. Regulating the nephron (water reabsorption) Alcohol inhibits release of ADH • Drink alcohol, • Inhibit ADH release • Water not reabsorbed from nephron tubule • Urinate a lot. • Dehydration occurs… Caffeine has the same affect Therefore alcohol and caffeine are called diuretics (make you pee)

  29. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? III. Human Excretory System D. Regulating the nephron (water reabsorption) i. Under hormonal control ii. Solute sensors in brain (too little solute = too much water) iii. Regulates blood pressure High [water] = high BP Negative feedback Alcohol inhibits release of ADH ADH = vasopressin

  30. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? III. Human Excretory System D. dialysis i. Kidneys are damaged a. toxic waste builds up, unregulated BP, unregulated pH, unregulated salt/water concentration b. causes - hypertension and diabetes (60%) -prolonged use of pain relievers, alcohol, other drugs and medicines ii. Dialysis machine “Artificial kidney” a. Dialysis = separation b. 3 times a week, 4 to 6 hours a session

  31. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? III. Human Excretory System D. dialysis

  32. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? III. Human Excretory System E. gout i. Hyperuricemia - elevated levels or uric acid in blood (we do make some uric acid when we break down purines) - causes 1. Accelerated generation of uric acid 2. Impaired excretion in kidney 3. Consumption of purine-rich diet as uric acid is breakdown product of purines - crystals of uric acid can form in joints (pain) = GOUT Humans make a small amount of uric acid when we break down adenine and guanine (purines), which is put into the urine by the kidneys.

  33. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? III. Human Excretory System E. gout

  34. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? III. Human Excretory System F. Kidney Stones (for Joel) i. AKA renal calculi ii. Form inside kidneys or bladder iii. Most made of Calcium oxalate crystals

  35. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? IV. The liver A. More functions than any other organ i. Bile production ii. Deamination and synthesis of urea from ammonia iii. Detox of alcohol and other drugs iv. Synthesize blood clotting factors v. Involved in blood glucose regulation (stores glucose as glycogen) vi. Forms lipoproteins - transport fat and cholesterol to body tissues

  36. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? IV. The liver A. More functions than any other organ i. Bile production ii. synthesis of urea from ammonia iii. Detox of alcohol and other drugs iv. Synthesize blood clotting factors Lipoprotein (ex. LDL) vi. Forms lipoproteins

  37. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? IV. The liver A. More functions than any other organ i. Bile production ii. Deamination and synthesis of urea from ammonia iii. Detox of alcohol and other drugs iv. Synthesize blood clotting factors v. Involved in blood glucose regulation (stores glucose as glycogen) vi. Forms lipoproteins - transport fat and cholesterol to body tissues So where do you think your blood goes straight after absorbing molecules at the small intestines?

  38. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? IV. The liver A. More functions than any other organ First “stop”…the liver. The hepatic portal express - nutrients and harmful chemicals go straight to liver from duodenum - detox before entering body, and modify nutrients (deamination, lipoprotein synthesis, etc…) Fig. 25.13

  39. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? IV. The Skin (not in book) Fig. 25.13

  40. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? IV. The Skin a. epidermis i. Top layer of skin ii. Protects body, keeps in moisture iii. Couple layers of living cells topped with many layers of dead cells iv. Holds skin pigment

  41. Chapter 25: Control of the Internal Environment AIM: How do organisms deal with metabolic waste? IV. The Skin b. dermis i. Layer underneath epidermis ii. Connective tissue iii. Nerve endings for heat/pressure/pain iv. Exocrine Glands (pores) - sebaceous (oil) gland - associated with hair - eccrine (sweat) gland -sweat = 99% water, bit of NaCl, waste products (urea) - thermoregulation, excretion, protection (slightly acidic to prevent bacterial and fungal growth) v. Blood vessels

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