Unit 4- water balance Flashcards
water balance
the bodys internal envionment of extracellula fluid must maintain a constant volume, solute content, and often temp. it is importand for human and other terrestrial vertebrates to maintain stable aq environmnet
Osmosis
The movement of water molecules from a region of high concentration to a region of lower concentration through a selectively permeable membrane.
Selective permeability
- Only a few specific solute molecules can move through
- Maintains difference in solute conc. on the two sides of a biological membrane (ie. cell membrane)
Osmotic pressure:
the pressure that results from a difference in solute concentration between the two sides of a selectively permeable membrane.
* ↑ [water] gradient, the ↑ the osmotic pressure difference
hyperosmotic (hypertonic)
the solution on one side of a permeable membrane that has the lower concentration of water
* Water tends to move to the hyperosmotic side
hypoosmotic (hypotonic)
the solution on one side of a permeable membrane that has the higher concentration of water
* Water tends to move from the hypoosmotic solution.
Isosmotic (isotonic)
two solutions that have equal water concentrations
Water Balance – Aquatic organisms
Living in the Ocean
- Seawater is 96.5% H2O
- Fish cells are 98.6% H2O
- Marine fish cells are hypo-osmotic (more H2O)
problem in Water Balance – Aquatic organisms
Living in the Ocean
- Lose H2O
- Gain too much salt
solution in Water Balance – Aquatic organisms
Living in the Ocean
- Drink lots of water
- Secrete salt through gills
- Excrete small amount of concentrated salty urine
Water Balance – Aquatic organisms Living in freshwater
- Freshwater is 100% H2O
- Fish cells are 98.6% H2O
- Freshwater fish are hyperosmotic (less water)
problem in Water Balance – Aquatic organisms Living in freshwater
- Lose salt
- Gain too much H2O by osmosis
solution in Water Balance – Aquatic organisms Living in freshwater
- Does not drink
- Salt absorbed by gills
- Large volume of dilute urine
Osmoregulation
Osmoregulation = biological processes involved in controlling the levels of water and salt in the body fluids and cells.
concentration of water and solutes
both inside and outside the cells must be kept in a constant balance. this requires continues movement of water by osmosis and movement of solutes by diffusion and active processes into and out of the cell (intracellular and extracellular fluid must be ISOMOTIC)
