Chapter 44    Controlling the Internal Environment

Objectives
An Overview of Osmoregulation
1. Define osmoregulation and excretion.
2. Define Define osmolarity and distinguish among isoosmotic, hyperosmotic, and hypoosmotic solutions.
3. Distinguish between osmoregulators and osmoconformers. Explain why osmoregulation has an energy cost.
4. Distinguish between stenohaline and euryhaline animals, and explain why euryhaline animals include both osmoconformers and osmoregulators.
5. Discuss the osmoregulatory strategies of marine animals.
6. Explain how the osmoregulatory problems of freshwater animals differ from those of marine animals.
7. Describe anhydrobiosis as an adaptation that helps tardigrades and nematodes to survive periods of dehydration.
8. Describe some adaptations that reduce water loss in terrestrial animals.
9. Describe the ultimate function of osmoregulation. Explain how hemolymph and interstitial fluids are involved in this process.
10. Explain the role of transport epithelia in osmoregulation and excretion.
   
  Water Balance and Waste Disposal
11. Describe the production and elimination of ammonia. Explain why ammonia excretion is most common in aquatic species.
12. Compare the strategies to eliminate waste as ammonia, urea, or uric acid. Note which animal groups are associated with each process and why a particular strategy is most adaptive for a particular group.
13. Compare the amounts of nitrogenous waste produced by endotherms and ectotherms, and by predators and herbivores.
   
  Excretory Systems
14. Describe the key steps in the process of urine production.
15. Describe how a flame-bulb (protonephridial) excretory system functions.
16. Explain how the metanephridial excretory tubule of annelids functions. Compare the structure to the protonephridial system.
17. Describe the Malpighian tubule excretory system of insects.
18. Using a diagram, identify and give the function of each structure in the mammalian excretory system.
19. Using a diagram, identify and describe the function of each region of the nephron.
20. Describe and explain the relationships among the processes of filtration, reabsorption, and secretion in the mammalian kidney.
21. Distinguish between cortical and juxtamedullary nephrons. Explain the significance of the juxtamedullary nephrons of birds and mammals.
22. Explain how the loop of Henle enhances water conservation by the kidney.
23. Explain how the loop of Henle functions as a countercurrent multiplier system.
24. Describe the nervous and hormonal controls involved in the regulation of the kidney.
25. Explain how the feeding habits of the South American vampire bat illustrate the versatility of the mammalian kidney.
26. Describe the structural and physiological adaptations in the kidneys of nonmammalian species that allow them to osmoregulate in different environments.
   

20. Distinguish between hibernation and aestivation.

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