Animal Osmoregulation and excretion.pptx

Role of phospholipids in salinity stress

1. 1 Lecture #11 – Animal Osmoregulation and Excretion

2. 2 Key Concepts Water and metabolic waste The osmotic challenges of different environments The sodium/potassium pump and ion channels Nitrogenous waste Osmoregulation and excretion in invertebrates Osmoregulation and excretion in vertebrates

3. 3 Osmoregulation ≠ Excretion All organismal systems exist within a water based environment The cell solution is water based Interstitial fluid is water based Blood and hemolymph are water based All metabolic processes produce waste Metabolic processes that produce nitrogen typically produce very toxic ammonia Water and Metabolic Waste

4. 4 Critical Thinking The cellular metabolism of _____________ will produce nitrogenous waste.

5. 5 Critical Thinking The cellular metabolism of proteins, nucleic acids, and ATP will produce nitrogenous waste.

6. 6 Water and Metabolic Waste All animals have some mechanism to regulate water balance All animals have some mechanism to regulate solute concentration All animals have some mechanism to excrete nitrogenous waste products Osmoregulation and excretion systems vary by habitat and phylogeny (evolutionary history)

7. 7 Animals live in different environments Marine….Freshwater….Terrestrial All animals must balance water uptake vs . water loss and regulate solute concentration within cells and tissues

8. 8 The osmotic challenges of different environments – water balance Water regulation strategies vary by environment Body fluids range from 2-3 orders of magnitude more concentrated than freshwater Body fluids are about one order of magnitude less concentrated than seawater for osmoregulators Body fluids are isotonic to seawater for osmoconformers Terrestrial animals face the challenge of extreme dehydration

9. 9 The osmotic challenges of different environments – solute balance All animals regulate solute content, regardless of their water regulation strategy Osmoregulation always requires metabolic energy expenditure

10. 10 The osmotic challenges of different environments – solute balance In most environments, ~5% of basal metabolic rate is used for osmoregulation More in extreme environments Less for osmoconformers Strategies involve active transport of solutes and adaptations that adjust tissue solute concentrations

11. 11 Water Balance in a Marine Environment Marine animals that regulate water balance are hypotonic relative to salt water (less salty) Where does water go???

12. 12 Critical Thinking Marine animals that regulate water balance are hypotonic relative to salt water – where does water go???

13. 13 Critical Thinking Marine animals that regulate water balance are hypotonic relative to salt water – where does water go??? Remember water potential! Ψ = P - s

14. 14 Critical Thinking Marine animals that regulate water balance are hypotonic relative to salt water – where does water go??? Water will always move from high ψ to low ψ Pressure is not important in this instance (no cell wall) Solute concentration is much higher in the saltwater environment than in the cytoplasm Water is constantly moving out of the animal by osmosis

15. 15 Water Balance in a Marine Environment Marine animals that regulate water balance are hypotonic relative to salt water They dehydrate and must drink lots of water Marine bony fish excrete very little urine Most marine invertebrates are osmoconformers that are isotonic to seawater Water balance is in dynamic equilibrium with surrounding seawater

16. 16 Solute Balance in a Marine Environment Marine osmoregulators Gain solutes because of diffusion gradient Excess sodium and chloride transported back to seawater using metabolic energy, a set of linked transport proteins, and a leaky epithelium Kidneys filter out excess calcium, magnesium and sulfates Marine osmoconformers Actively regulate solute concentrations to maintain homeostasis

17. 17 Figure showing how chloride cells in fish gills regulate salts Specialized chloride cells in the gills actively accumulate chloride, resulting in removal of both Cl - and Na +

18. 18 Solute Balance in a Marine Environment Marine osmoregulators Gain solutes because of diffusion gradient Excess sodium and chloride transported back to seawater using metabolic energy, a set of linked transport proteins, and a leaky epithelium Kidneys filter out excess calcium, magnesium and sulfates Marine osmoconformers Actively regulate solute concentrations to maintain homeostasis

19. 19 Water Balance in a Freshwater Environment All freshwater animals are regulators and hypertonic relative to their environment (more salty) Where does water go???

20. 20 Critical Thinking All freshwater animals are regulators and hypertonic relative to freshwater – where does water go???

21. 21 Critical Thinking All freshwater animals are regulators and hypertonic relative to freshwater – where does water go??? Solute concentration is much lower in the freshwater environment than in the cytoplasm Water is constantly moving by osmosis into the animal

22. 22 Water Balance in a Freshwater Environment All freshwater animals are regulators They are constantly taking in water and must excrete large volumes of urine Most maintain lower cytoplasm solute concentrations than marine regulators – helps reduce the solute gradient and thus limits water uptake Some animals can switch environments and strategies (salmon)

23. 23 Some animals have the ability to go dormant by extreme dehydration http://www.youtube.com/watch?v=CKamWp610ng The waterbear song by MalWebb