1. Maintaining Homeostasis
Passive and Active Transport

2. Lesson Objectives
Understand how equilibrium is established as a result of diffusion.
Distinguish between diffusion and osmosis.

3. Cellular Membrane
Membrane: function is to control what enters and exits the cell
Selectively permeable

4. Homeostasis All living cells exists in a liquid environment
Internal conditions need to remain constant
Homeostasis
Equilibrium=everything is balanced
Maintain homeostasis by regulating movement of molecules across the membrane
Passive Transport (no energy required)
Active Transport (energy required)

5. Passive Transport: Diffusion
Movement of materials across the cell membrane without using energy
Diffusion:
Movement of material/molecules from an area of high concentration to an area of low concentration
Concentration Gradient

6. Passive Transport: Osmosis
When water diffuses across the cell membrane
hill.com/sites/ /student_view0/chapter2/animation__how_osmosis_works.htm l

7. Effects of Osmosis on Cells
Hypotonic:
Hypertonic:
Isotonic:
Lower solute concentration outside of the cell
Higher solute concentration outside of the cell
Concentration is the same inside and out
Water moves into the cell
Water moves out of the cell
Water moves in and out
Cell swells
Cell Shrinks

10. How does water move? “Salt Sucks”

11. How does water move? “Salt Sucks”

12. How does water move? “Salt Sucks”

13. Osmosis In Nature
Cytolysis: in a hypotonic solution red blood cells will continue to swell until they burst
Penicillin killing bacteria
Contractile Vacuole: organelle in protist cells that pumps excess water out
Turgor Pressure: water pressure placed on the cell wall to give plant cell its shape
Plants wilting if solution is hypertonic
Don’t drink salt water
Diarrhea
Something in stools that is drawing out the water

14. Facilitated Diffusion
Movement of particles from higher concentration to lower concentration
Large molecules may require “help”, they use carrier proteins
Nervous system uses Na and Ca pumps

15. Lesson Objectives Distinguish between passive and active transport.
Explain how sodium-potassium pumps operate.
Compare and contrast endocytosis and exocytosis.

16. Active Transport Active Transport
Passive Transport: down concentration gradient

17. Active Transport
Passive
Active

18. Active Transport
Requires energy to move molecules up their concentration gradient
Low concentration to high concentration
Sodium-Potassium Pump
Exocytosis
Endocytosis

19. Cell Membrane Pumps Requires a carrier protein 3 Na-2 K
Requires energy
hill.com/sites/ /student_view0/chapter2/animation__how_the_sodium_potassium_p ump_works.html

20. Endocytosis
Phagocytosis
Pinocytosis

21. Exocytosis