Regulating water content Flashcards
What is osmotic concentation?
Total concentration of all solutes in a water solution
What is an osmoconformer?
this means water enters and leaves equally, no overall change in water content of organisms
What is the concentration like in osmoconformers?
Their internal concentrations of individual solutes are not necessarily the same as in sea water
What are sharks?
osmoconformers but can regulate ions
What do sharks body fluids have?
almost the same concentration of ions as seawater, but they use different ions
What do shark kidneys do?
enables reabsorption of large amounts of urea into the blood, which makes their urine much less concentrated
Whar do sharks have to deal with?
a slight influx of salt, which is excreted by a rectal gland
What is osmoregulation?
process by which living organisms maintain the solute and water concentration in their blood and body fluids
What is the issue with osmoregulators
- Marine vertebrates with osmotic concentrations of solutes lower than that of seawater and so lose water by osmosis through the skin and gain Chloride ions though the skin
- They require mechanisms to maintain their body solute and water content
Explain osmoregulation in marine fish
- have an internal solute concentration approx 1/3 of sea water
- tend to lose water (by osmosis) to their environment
- mainly across the permeable gill surface
What happens during osmoregulation?
Excess salts in the sea water they drink are absorbed into the blood in the intestine. This causes the plasma to be high in chloride, which would dehydrate cells
How is chloride excreted?
-Some salts lost in concentrated urine (hypertonic)
-Sodium and chlorine ions are
actively secreted by chloride
secretory cells (present in gills)
-Process requires energy
What does salt form?
sodium ions and chloride ions in the blood of marine fish
What do chloride sells absorb?
excess chloride ions from the blood and actively excrete them from the gills (requires ATP and therefore many mitochondria)
Why do cell mebranes increase surface area?
for more excretion of chloride ions
What is mitochondria used for?
- produce ATP/energy
- ATP is needed for active transport
- site for respiration
What is the chloride cell?
Sites of ion transport in fish gills
What is euryhaline?
Organisms able to osmoregulate in (tolerate) a range of salinities (can move from salt water to brackish and sometimes fresh)
-Species of fish which migrate from sea into fresh water
What do euyhaline organisms use?
Use different mechanisms to control ions in their cells in their different environments
Where do salmon spend part of their life cycle?
in fresh water and part in sea water as they reproduce in fresh water and can keep osmotic concentration of their blood stable in both
What is the osmotic concentration of blood like in fresh water
It is more concentrated than fresh water
What hapens when water enters the fish
it dilutes the blood
What difufuses out from the salmon
chloride ions
Where are almon able to excreet excess water?
through the kidneys
What do salmon uptake through their gills?
chloride
What is stenohaline?
organisms that have limited tolerance to changes in salinity (salinity cannot change too much)
