Osmoregulation and excretion


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Osmoregulation and excretion

  1. 2. WATER GAIN (milliliters) WATER LOSS (milliliters) by ingesting solids by ingesting liquids by metabolism in urine in feces by evaporation 6.0 0.0 54.0 60.0 850 1,400 350 2,600 13.5 2.6 43.9 60.0 1,500 200 900 2,600 KANGAROO RAT HUMAN
  2. 3. Maintaining water balance is tricky! These are actually two different problems – with one mechanistic solution!
  3. 4. 2% sucrose solution 1 liter of distilled water 1 liter of 10% sucrose solution 1 liter of 2% sucrose solution Hypotonic Conditions Hypertonic Conditions Isotonic Conditions Tonicity and Osmosis
  4. 7. PROBLEMS salt in food FRESHWATER FISH MARINE BONY FISH s S (hyper) (hypo) W w large volume dilute urine S s (hyper) (hypo) w W PROBLEMS drinks sea water salt AT out of blood by gills small volume urine salt AT into blood by gills
  5. 8. LOSS GAIN H 2 O SOLUTE 1. Absorbed by gut - solid foods - beverages 2. Metabolic H 2 O 1. Urine 2. Evaporation - skin (sweat) - lungs 3. Feces 1. Absorbed by gut 2. Secreted by cells - hormones 3. Metabolism - CO 2 - ammonia - urea - uric acid 4. Respiration - O 2 <ul><li>Sweat - NaCl </li></ul>2. Respiration - CO 2 3. Urine
  6. 9. US water contest radio sacks 10 The KDND 107.9 station in Sacramento sacked the hosts of its morning show and other members of staff. The show had challenged listeners to drink as much water as they could to win a Nintendo Wii video game system. One participant - Jennifer Strange - later died as a result of drinking too much water, initial tests showed. Ms Strange, 28, said she wanted to win the game - &quot;Hold Your Wee for a Wii&quot; game - for her children. A work colleague said Ms Strange had complained her head was hurting hours after the contest and was going home. She was found dead on Friday at her house in Rancho Cordova. The Sacramento County coroner later said preliminary autopsy findings suggested she had died of water intoxication.
  7. 10. kidney ureter bladder urethra diaphragm adrenal gland aorta vena cava renal artery renal vein
  8. 11. Kidney Blood Flow
  9. 12. ureter renal artery cortex medulla medulla cortex pelvis ‘ funnellike’ renal vein Bowman’s capsule proximal distal loop of Henle (in medulla) collecting duct cortex medulla
  10. 13. <ul><li>Filtration – in the glomerulus (~49 gal / day) </li></ul><ul><li>Reabsorption – along tubule </li></ul><ul><li>Secretion – in distal tubule (mostly) </li></ul>Bowman’s capsule glomerular capillaries peritubular capillaries (thread around tubule) glomerulus
  11. 14. Nephron Anatomy <ul><li>Millions of these units accomplish the filtering of blood </li></ul>
  12. 15. <ul><li>Filtration occurs here through fenestrations </li></ul><ul><li>Formed elements and plasma proteins remain </li></ul>
  13. 22. How is the osmoregulatory economy regulated?
  14. 23. How is the osmoregulatory economy regulated?
  15. 24. Osmoregulation <ul><li>Too many solutes! </li></ul><ul><ul><li>Stimulates release of ADH </li></ul></ul><ul><ul><li>Increases permeability on distal tubule </li></ul></ul><ul><ul><li>More H 2 O reabsorbed </li></ul></ul><ul><li>Too few solutes! </li></ul><ul><ul><li>ADH levels decrease </li></ul></ul><ul><ul><li>Decreases permeability of distal tubule </li></ul></ul><ul><ul><li>Less H 2 O reabsorbed </li></ul></ul>
  16. 25. Osmoregulation <ul><li>BP / volume too low! </li></ul><ul><ul><li>Renin released </li></ul></ul><ul><ul><li>Arterioles constricted </li></ul></ul><ul><ul><li>Aldosterone released </li></ul></ul><ul><ul><li>More H 2 O reabsorbed </li></ul></ul><ul><li>BP / volume too high! </li></ul><ul><ul><li>Renin not released </li></ul></ul><ul><ul><li>Arterioles relaxed </li></ul></ul><ul><ul><li>Less aldosterone produced </li></ul></ul><ul><ul><li>Less H 2 O reabsorbed </li></ul></ul>
  17. 26. The long, slow journey into night… <ul><li>Symptoms of heart failure </li></ul><ul><ul><li>Shortness of breath </li></ul></ul><ul><ul><li>Weight gain from fluid buildup </li></ul></ul><ul><ul><li>Swelling that gets worse at the end of the day or after standing for long periods </li></ul></ul><ul><ul><li>Shoes may no longer fit </li></ul></ul><ul><ul><li>Abdominal swelling </li></ul></ul><ul><ul><li>Why? </li></ul></ul>