1. Homeostasis and Transport
Mr. Pumphrey

2. The Cell Membrane Made of lipids and protiens
“Selectively Permeable”: only allows certain things to enter the cell
The lipids control water loss
Small molecules
pass through easily
( Ca, Na, Cl, K).

3. HOMEOSTASIS
Stable level of internal conditions. (temperature, water levels, PH etc.)

4. Equilibrium
Concentration of molecules is equal inside the cell and outside of the cell
Organisms achieve homeostasis by cells achieving equilibrium
Concentration:
Amount of a molecule or liquid

5. Passive Transport Transport that does NOT require energy 1) Diffusion
2) Osmosis
3) Facilitated Diffusion

6. 1)Diffusion
Movement of Molecules from higher concentration to lower concentration until equal
“gradient”= difference in amounts
****Molecules may be anything that is not water such as Calcium, Potassium, or Sodium****

7. Diffusion

8. Carbon dioxide and oxygen are molecules that can move freely across a plasma membrane. What determines the direction that carbon dioxide and oxygen molecules move?
1) orientation of cholesterol in the plasma membrane
2) concentration gradient across the plasma membrane
3) configuration of phospholipids in the plasma membrane
4) location of receptors on the surface of the plasma membrane

9. 2) Osmosis Movement of water across the cell membrane
High to low concentration until equal
Does not require energy it is passive

10. 3) Facilitated diffusion
Larger molecules will move through membrane proteins
Passive: no energy needed
move from high conc. to low conc. Until equal

11. Concentration Gradient
Concentration Gradient is the difference in the concentration of solutions on either side of a membrane

12. Direction of osmosis
Hypotonic: having a lower solute concentration, and therefore a higher water concentration, outside of the cell.
Hypertonic: Having a greater solute concentration, and therefore a lower water concentration, outside of the cell.

13. Chart
Isotonic-having an equal solute concentration and water concentration relative to another solution.
Direction of osmosis
Hypotonic
Water into the cell
Hypertonic
Water out of the cell
Isotonic =
Into and out of the cell at equal rates
Direction of Osmosis
Solution outside of cell

15. How Cells Deal With Osmosis
Most get to equilibrium easily as water passes across membranes
Cells live in a hypotonic environment, water all around them
If too much water enters the cell it will burst
Cells must manage water and solute levels to prevent dehydration

16. Cell membrane and facilitated diffusion

17. Active Transport
Active transport requires ATP (energy) and moves molecules from less to more (against the gradient)
1) Sodium-Potassium Pump
2) Endocytosis
3) Exocytosis

18. Endocytosis and Exocytosis
2) Endocytosis: large molecules like food into the cell
3) Exocytosis: Large molecules out of the cell

19. Sodium Potassium pump
From low to high concentration—AGAINST concentration
gradient
Uses energy-”Active”
1) Sodium-potassium pump: in muscle cells uses energy
Creates electrical impulses like in nerve cells
Must have an imbalance of molecules for cells to work

20. Sodium Potassium Pump

21. Sodium Potassium pumps
Loss of electrolytes due to sweating stops sodium-potassium pumps
Causes dehydration in animal cells
The levels of sodium outside the cell and potassium inside must always be kept intact

22. Exocytosis and Endocytosis

23. Transports process Maintains Homeostasis
Cells of animals live in a salty or “saline” solution
This allows them to survive in a variety of different environments
Cells must maintain fluid levels or they die
Most animals will have a kidney type organism to manage these levels in the body

24. The Kidney

25. Kidneys help maintain homeostasis
Filter the blood of animals through osmosis and diffusion
Prevent dehydration and maintain fluid levels
Prevent toxins from building up in the blood
Eliminate swelling in the body

26. Lungs and Homeostasis
Lungs are responsible for maintaining balance of Oxygen
“Alveoli” are small structures that allow exchange of oxygen and carbon dioxide in the blood (diffusion)

27. Intestines and Homeostasis
Intestines have folds called “villi”
Villi increase the surface area of the intestines (diffusion of food)
Allow more area for diffusion of molecules and osmosis. (digestions and absorption)