bio - osmoregulation

what is osmoregulation and excretion?

osmoregulation: the process by which an organism controls balance of water/solute []

excretion: rids the body of nitrogenous metabolites and other waste products

what is osmorality/osmolality?

they determine the direction of movement of water across a selectively permeable membrane

osmolarity: per litre of solution

osmolality: per kg of solvent

differentiate diffusion and osmosis:

diffusion: particles go from high [] to low [] of solute

osmosis: water moves from high [solute] to low [solute]

talk about the aquaporins slide

aquaporins are the channels allowing water to pass through, allow water to move quickly across the cell

Cells with aquaporins: water rushes into the cell, and they burst eventually

Cells without aquaporins: water moves in very slowly, cells stay mostly the same

🚗 Bottom analogy (very important)

• Road with few cars → fast movement = water through aquaporins

• Traffic jam → slow movement = water without aquaporins

what is Hplus selectivity of aquaporins?

it means they allow everything in BUT Hplus ions. This is good because Hplus ions could destroy the proton gradients.

Protons move by the Grotthus mechanism: a proton being passed along a chain of water molecules (like a relay race). A continous chain of water molecules is needed

talk about the slide of Facing Osmotic Challenges:

The following words explain how organisms deal with salt (salinity) and water balance in their environment

Osmoconformers: animals, like marine mammals, that match their internal osmolarity to the environment. Their body fluids have similar solute [] as the surrounding water

Osmoregulators: animals that regulate their internal osmolarity, like fish and humans

Stenohaline: organisms that can tolerate only a narrow range of salinity, very sensitive to changes

Eurhaline: organisms that can tolerate a wide range of salinity, can move between freshwater and saltwater

talk about energetics of osmoregulation:

this means how much ATP an organism must spend to maintain water and salt balance

It costs energy because ions move against the concentration gradients, so it requires active transport

Osmoconformers: low energy cost because internal conditions = environment

Osmoregulators: high energy cost, because they have to pump ions ion/out

what is osmoregulation in aquatic organisms:

talk about marine animals:

talk about freshwater animals:

talk about animals that move between freshwater and seawater

talk about the anhydrobiosis adaptation: