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Chapter 44

Chapter 44. Osmoregulation and Excretion. Selectively permeable membrane. Fig. 44-2. Solutes. Net water flow. Water. Hypoosmotic side. Hyperosmotic side. Osmoregulation. Osmoregulation - the control of the concentration of body fluids.

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Chapter 44

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  1. Chapter 44 Osmoregulation and Excretion

  2. Selectively permeable membrane Fig. 44-2 Solutes Net water flow Water Hypoosmotic side Hyperosmotic side

  3. Osmoregulation Osmoregulation- the control of the concentration of body fluids. Diffusion- movement of substance from an area of greater concentration to an area of lower concentration Osmosis- diffusion of water through a semipermeable membrane

  4. Adaptation to Marine Environment • Reducing salt • Seabird and marine iguana- nasal salt secreting gland • Sea snake- sublingual gland • Crocodile- lacrimal gland • Fish gills- chloride cells • Shark- rectal gland

  5. Salt Excretion in Birds

  6. Nitrogenous Waste Excretion • Ammonia- toxic • Excrete directly into water- jellies • Detoxifyurea • Urea- need lots of water to get rid of • Uric Acid- birds & reptiles • more costly to produce than urea, but needs less water to be removed

  7. Strategies to remove Nitrogenous Waste

  8. Balancing NaCl in Blood • Osmoconformer: isoosmotic • Osmoregulator: hyper-, hypo-, ureoosmotic • Euryhaline: wide tolerance range • Stenohaline: narrow tolerance range Osmols- total solute concentration in moles of solute/liter of solution

  9. Marine Fish: hypoosmotic Less salt than external environment H2O continually leaves body continually drinks seawater excretes salt through gills produces small amts of dilute urine

  10. Freshwater Fish: hyperosmotic H2O continually enters body does not drinks water More salt than external environment produces large amts of dilute urine

  11. Shark and Coelacanth: ureoosmotic Maintains high levels of urea and TMAO in blood excretes salt through rectal gland coelacanth Rana cancrivora

  12. Hagfish: ionosmotic nonregulator Seawater concentration = internal concentration

  13. Osmolarity in Freshwater and Saltwater Osmolarity- measure of total solutes(dissolved particles) Ions FW m osmol/l SW m osmol/l Na+ 1 470 Cl- 1 550 Ca++ variable 10 Total 10 1000

  14. Habitat Na+ Cl- Urea seawater sw 478 558 hagfish (Myxine) sw 537 542 lamprey fw 120 96 Goldfish (Carassius) fw 115 107 Toadfish (Opsanus) sw 160 Crab-eating frog (Rana) sw 252 227 350 Dogfish sw 287 240 354 freshwater ray fw 150 149 <1 coelacanth sw 197 199 350 Concentration of Ions

  15. Adaptations to Dry Environment • Many desert animals don’t drink water • Kangaroo rats lose so little water that they can recover 90% of the loss from metabolic water and gain the remaining 10% in their diet of seeds. • Also have long loop of Henle

  16. Most excretory systems produce a filtrate by pressure-filtering body fluids into tubules.

  17. Diverse excretory systems are variations on a tubular theme • Flatworms have an excretory system called protonephridia, consisting of a branching network of dead-end tubules. • The flame bulb draws water and solutes from the interstitial fluid, through the flame bulb, and into the tubule system.

  18. Metanephridia consist of internal openings that collect body fluids from the coelom through a ciliated funnel, the nephrostome, and release the fluid through the nephridiopore. • Found in most annelids, each segment of a worm has a pair of metanephridia.

  19. Insects and other terrestrial arthropods have organs called Malpighian tubules that remove nitrogenous wastes and also function in osmoregulation. • These open into the digestive system and dead-end at tips that are immersed in the hemolymph.

  20. Nephron

  21. Hormonal Control via Negative Feedback

  22. Regulation of Aldosterone secretion byrenin-angiotensin-aldosterone(RAA) pathway Fig. 18.16

  23. Moment of Zen

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