1. Osmoregulation Part 2

2. Monday On Monday we covered 3 negative feedback loops that regulate water balance Today: we will cover some of the adaptations found in animals that live these environments – Arid – Wet – Salt water/ marine – Fresh water

3. Arid Concentrated urine – Long loop of Henley= more water filtered out of urine – Urine is Hypertonic- it has more solutes (urea, uric acid, ammonia) than other body fluid of the animal Reptiles – Larger number of kidney tubules which can be inactive if dehydrated (filtering of blood is slower) – Ureta empties into the cloaca where more water is reabsorbed (this is reptile/bird speak for the anus) Dry faeces Storage of water in other ways- eg. Camels have a higher water content in their blood. The problem in arid areas is how to conserve water and stay cool (sweating a lot is not the best response)

4. Wet Osmoregulation in wet environments is not so problematic BUT! – Single celled organisms will continue to absorb water via osmosis until they burst – UNLESS they have a contractile vacuole to expel excess water – Plants have cell walls to ensure that water absorbed stops

5. Marine Fish- – urine is isotonic (same amount of solutes as body fluids) – Drink sea water and secrete salts through the gills – Only a small amount of urine produced Birds – Water reabsorbed in the cloaca – Salt excreted via salt glands above the eye

6. Freshwater Fish – urine is diluted= hypotonic – Don’t drink water Frogs – Diluted urine in large quantities – Active transport of ions through the skin (to make up for those lost by diffusion) – Able to produce concentrated urine when conditions are dry

7. Now let’s look at some examples! See activity