Ion and Water Balance Flashcards
Whats osmoregulation?
Regulation of ion and water balance
What are 2 different strategies to meet ionic challenges?
- Osmoconformer – internal osmolarity = external osmolarity
- Osmoregulator – regulate equilibrium
- Active regulation of the osmotic pressure of an organism’s body fluids, detected by osmoreceptors, to maintain the homeostasis
What are 2 salt tolerances?
Stenohaline - able to tolerate only a narrow range of salinity.
Euryhaline – able to tolerate a wide range of salinity
What is osmolarity? Of sw sharks, sw cod, and fw perch?
Measures the body’s electrolyte-water balance
-Sharks- Seawater: 1200 mOsM
shark plasma osmolarity: 1200 mOsM, but [salt] «_space;SW Isomotic
-Cod- Seawater: 1200 mOsM
Cod plasma osmolarity: 350 mOsM hyposmotic
- Perch- Freshwater: < 10 mOsM
Perch plasma osmolarity: 350 mOsM hyperosmotic
How do terrestrial animals obtain water?
Through diet or metabolism
What 3 levels can ion and water balance can be maintained at?
- Cells
- Epithelial tissues
- Kidney
What do epithelial tissues form?
Form boundary between animal and environment
What are keratinocytes in epithelial tissue?
Secrete proteins and lipids to form a dense hydrophobic extracellular matrix
What are 4 epithelial Tissue Properties for Ion Movement?
- Asymmetrical distribution of membrane transporters.
- Cells interconnected to form impermeable sheet of tissue. (junctions
- High cell diversity within tissue.
- Abundant mitochondria.
What are 2 routes of transport for solutes? What do they use?
1. Transcellular- travel through the cell, passing through both the apical membrane and basolateral membrane 2. Paracellular- passing through the intercellular space between the cells *Use-Na+/K+ ATPase ion channels cotransporters exchangers
How is oxygen exchanged in fish gills?
Passes over the gills
Start= high o2
End=low o2
What are fish gill lamellae composed of?(3)
Mucous cells
Mitochondria-rich chloride cells
Pavement cells
What does ion transport in fish gills depend on?
Depends on water salinity
What fish can migrate between saltwater and freshwater? How?
- Diadromous fish
- Smoltification- physiological changes
What are salt glands? Who has them?
- Excrete hyperosmotic solutions of Na+ and Cl-
- Hyperosmotic solutions produced by ion pumps and a countercurrent multiplier
- Reptiles and birds
How is nitrogen excreted (three forms)?
- Ammonia
- Uric acid
- Urea
What are ammonia excretion advantages and disadvantages?
Ad- Little E to produce
Dis- Toxic; must be excreted in lots of water
What are uric acid excretion advantages and disadvantages?
Ad- Little water excreted with it and low toxicity
Dis- Lots of E to produce
What are urea excretion advantages and disadvantages?
Ad-Less toxic= less water
Dis- A little more E to produce
What do Condricythyan fish use urea for?
To increase tissue osmolarity