1. Homeostasis and Cell Transport
5.1 Passive Transport
5.2 Active Transport

2. Homeostasis Biological balance with the environment
Dynamic Equilibrium
- occurs when the concentration of
molecules of a substance is the same across
a space
Works to control what enters and exits the cell.

3. Permeability Allowing a substance to pass through a membrane.
Selectively Permeable
- only allowing some substance to pass
through the membrane
- based on size, shape, type
- important in maintaining homeostasis

4. Passive Transport - diffusion - facilitated diffusion - gated channels
NO CHEMICAL ENERGY IS USED
Spontaneous
Examples:
- osmosis
- diffusion
- facilitated diffusion
- gated channels

5. substance across a space
Diffusion
Moving from high concentration to low concentration
Concentration Gradient
- difference in concentrations of a
substance across a space
Osmosis
- diffusion of water

6. Example of Diffusion

7. Example of Osmosis

8. Hypertonic Solutions
Concentration of solute in the environment is greater than that of the cell
- higher concentration of water inside
the cell
- water moves outside of the cell
Plasymolysis: plant cells
Crenation: animal cells

9. Hypotonic Solutions
Concentration of solute in the environment is less than that of the cell
- higher concentration of water outside
the cell
- water moves into the cell
Cytolysis: animal cell
Turgid: plant cell (homeostasis)
Contractile Vacuole for protists

10. Isotonic Solutions
Concentration of solutes inside and outside the cell are equal
No net movement of water
Flaccid: plant cells (fatal)
Animal cells: homeostasis
RBC’s .9% saline

11. RBC…what type of solution?

12. RBC…what type of solution?

13. RBC…what type of solution?

14. Keep in mind…

15. Passive Transport (2) Facilitated Diffusion
- use of carrier molecules or transport
proteins
-molecules are too large or not soluble in
lipids
EX. Glucose and Insulin
Ion Channels
- protein controlled passage
- solutes enter on an “as needed” basis
EX. Nerve Cells

16. Facilitated Diffusion

17. Diffusion vs. Facilitated Diffusion

18. Ion Channel

19. Active Transport - Endocytosis (pinocytosis and phagocytosis)
Requires the use of CHEMICAL ENERGY (ATP)
Examples:
- Sodium-Potassium Pump
- Endocytosis
(pinocytosis and phagocytosis)
- Exocytosis

20. Sodium-Potassium Pump
Occurs in muscle cells
Found in the plasma membrane
3 Sodium (Na+) leave and 2 Potassium (K+) enter AGAINST the concentration gradient
Uses carrier molecules

21. Sodium-Potassium Pump

22. Endocytosis
Allows large molecules to enter the cell without passing through the cell membrane
Phagocytosis
solid particles
Ex. white blood cells
Pinocytosis
liquid particles
Ex. Electrolytes entering the cell

23. Endocytosis

24. Exocytosis
Allows large molecules to exit the cell without passing through the cell membrane
Uses vacuoles and vesicles
-proteins made in the ribosomes are
released in this fashion after they travel to
the golgi apparatus
-contractile vacuoles

25. Exocytosis