Chapter 44 Flashcards
What are all cells bathed in?
Fluid
Why must concentrations of water and solutes be regulated?
for physiological functions
What is osmoregulation?
homeostatic control of internal solute concentrations
What would happen if a cell were hyperosmotic to its environment?
the cell would be saltier than the environment, water would move in, cell would lyse / burst.
What would happen if a cell were isoosmotic to its environment?
the cell and its environment would have equal amounts of salt; water would be moving in and out at equal rates
What would happen if a cell were hypoosmotic to its environment?
The cell would be less salty compared to its environment; water would move out towards the environment, so cell would shrivel.
These organisms do not regulate internal solute concentrations
osmoconformers
Give an example of an osmoconformer
marine organisms
If an organism is hypo or hyper osmotic to its environment, what must it do to change this?
expend energy
explain the tonicity of a bony fish
it is hypoosmotic to its environment. they gain salt ions from food and sea water, they loose water by osmosis, excrete salt from gills, along with their urine.
explain the tonicity of a freshwater bass?
it is hyperosmotic to its environment. It will gain water by osmosis (because it is saltier than its environment).
what do terrestrial animals risk?
dessication
how to terrestrial animals gain water?
food and drink
what do all animals produce?
nitrogenous waste
whats the problem with nitrogenous wastes?
they are toxic!!!
how do animals get rid of nitrogenous wastes?
excretion
describe ammonia as a waste product.
very soluble, very toxic so must be disposed of with lots of water. It is most common in aquatic species.
describe urea as a waste product.
less toxic than ammonia, requires less water for disposal, more energetically expensive. Mammals and most amphibians utilize this.
describe uric acid as a waste product.
least toxic of the three wastes, requires the least amount of water as it is insoluble. However, it is the most energetically expensive. Reptiles, birds, and insects use this.
Why do reptiles, birds, and insects use uric acid?
because they are at the most risk of dessication, they want to loose the LEAST amount of water, so spending more energy is better than death.
What are the four steps of the excretory process?
Filtration, reabsorption, secretion, excretion
What happens during the filtration step?
hydrostatic pressures force water and small molecules into the excretory system. Creates the filtrate
What molecules does the filtration step force in?
sugars, amino acids, nitrogenous wastes
What happens during the reabsorption step?
valuable molecules are reabsorped into the body fluids
