1. Cells & Systems
Topic 4

2. Fluid Movement in Cells
All the actions you do to maintain life (eat, drink, breathe etc) are carried out at the cellular level
Your cells do what you do!
Cell membrane controls what enters and leaves the cell.
It is selectively permeable; only allowing certain materials to cross the membrane

3. Diffusion The process of substances spreading out.
Particles of a substance naturally want to be evenly distributed…
Observe adding food colouring or ink to water…
Diffusion in cells…
concentration of dissolved substances in the fluid surrounding the cell may be the same as the concentration inside the cell.
Therefore the substance may pass freely across and the cell membrane in order to even out the concentration.
DO the demo of food colouring in water

4. Diffusion…the equalizer of concentration

5. Osmosis
The diffusion of water across a selectively permeable membrane.

6. 3 states of concentration
Hypertonic: having a higher osmotic pressure than a particular fluid.
Isotonic: denoting or relating to a solution having the same osmotic pressure as some other solution.
Hypotonic: having a lower osmotic pressure than a particular fluid.