Osmoregulation and Excretion

1.  Why must organisms thermoregulate?

2.  Describe some mechanisms by which organisms gain or loose heat.

3.  Compare and contrast thermoregulation in ectotherms and endotherms with respect to:
4.  What is torpor?  Describe the different states of torpor (hibernation, estivation) and their adaptive significance.

5.  Why must organisms regulate their internal body fluids?

6.  Why can most aquatic animals excrete nitrogenous wastes as ammonia?  Why do most terrestrial animals excrete nitrogenous wastes as urea or uric acid?   What are the advantages of excreting uric acid for animals like birds and reptiles?

7.  Why must animals osmoregulate?  Describe the differences between hyperosmotic, hypoosmotic, and isoosmotic solutions.  Define osmolarity.

8.  Compare and contrast aquatic osmoconformers and osmoregulators.
9.  What is the main osmotic problem that terrestrial animals face?

10. Describe the three general processes common to animal excretory systems.

11. Compare and contrast the excretory systems of invertebrates and vertebrates.

12. Describe the anatomy of the mammalian kidney.  Your discussion should include the following terms renal artery, renal vein, ureter, renal cortex, renal medulla, and renal pelvis.

13. Trace the pathway of a molecule of urea from the time it enters the nephron until it is excreted into the renal pelvis.  As you do this consider the following:

14. How are cortical nephrons different from juxtamedullary nephrons?  Describe how juxtamedullary nephrons allow mammals to generally excrete hyperosmotic urine.  Why is this adaptive?

15. When might it be beneficial to excrete hypoosmotic urine?  What other organ systems participate in regulating urine output?

16. Describe some of the diverse adaptations that have evolved in the vertebrate kidney.