Waste Excretion Flashcards
1
Q
What yields water and CO2?
A
- lipid, carb and protein catabolism
2
Q
What is another result of protein/amino acid catabolism?
A
- ammonia
3
Q
What is wrong with ammonia?
A
- toxic (neurotoxic)
4
Q
What functions as an ammonia transporter?
A
- rhesus glycoproteins on NH3 channel
5
Q
What is the prodominant site of ammonia secretion? by how much?
A
- gill
- 6-20 fold (90% ammonia, 10% urea)
6
Q
How does ammonia get into fish?
A
- from water as NH3 but cellular toxicity due to NH4 in many tissues
7
Q
What is ammonia excreted as once detoxified?
A
- urea
8
Q
What is the issue with urea production?
A
- energetically costly (5 ATP)
9
Q
What does ureotelic mean?
A
- urea main nitrogenous excretory product
10
Q
What pathway allows elasmobranchs, african lungfish, tilapia, toadfish and larval fish to be ureogenic?
A
- ornithine-urea-cycle
