BIO-8 Lecture Notes - Lecture 5: Sodium Chloride, Semipermeable Membrane, Saltwater Fish
Document Summary
Aquatic environments challenge the balance of water and salt in animals. Water inside and outside an organism often contains diff. locations. Water moves to equalize solute concentrations in diff locations. Semipermeable membranes: membranes that allow only particular molecules to pass through; reduces free movement of solutes. Osmosis: movement of water across a semipermeable membrane. Osmotic potential: the force with which a solution attracts water by osmosis. Osmoregulation: mechanisms organisms use to maintain a proper solute balance: hyperosmotic: tissue solute concentrations are higher than surrounding water, hypoosmotic: tissue solute concentrations are lower than surrounding water. Osmoregulation in fish: exchanges of water and solutes differ between freshwater and marine fish. Freshwater fish are hyperosmotic: they have a higher salt concentration in their body than exists in the surrounding water. To maintain salt balance they must excrete large amounts of water and use their gills and kidneys to actively retain salts.
