Marine Teleosts and Lampreys - Hyposomregulators Flashcards
1
Q
What 4 strategies are used for hyposmoregulation?
A
- impermeable tegument
- drink salt water
- active Na and Cl extrusion via saltwater ionocytes
- kidneys role limited to excretion of toxic divalents
2
Q
What is the advantage of an impermeable tegument?
A
- minimize NaCl uptake and water loss
3
Q
What is the advantage of drinking saltwater?
A
- active absorption of ions and water across the gut
4
Q
What are the characteristics of active Na and Cl extrusion?
A
- shallow tight junctions
- deep apical crypt
- associated with accessory
5
Q
What is the process of drinking saltwater? (3)
A
- imbided SW desalinated in esophagus and stomach
- water in intestine iso-osmotic with blood
- Ca2 and Mg2 in SW not absorbed
6
Q
What does NaCl carry when it is absorbed?
A
- water
6
Q
What does it mean for salt water to be desalinated?
A
- remove some salt (excrete from gills)
7
Q
What is osmotic water drag?
A
- more salt = pull water along
8
Q
What happens to Ca and Mg that is not absorbed?
A
- precipitated by secreted HCO3 as carbonates CaCO3 and MhCO3
9
Q
What does precipitation mean?
A
- take Ca and Mg ouot of solution
10
Q
Drinking saltwater adds to ___ ___. what is excess salt excreted by?
A
- salt load
- by gill chloride cells
