1. Homeostasis

2. Homeo-What? Homeo= Same Stasis= State
Homeostasis: Maintaining a constant internal balance
Example: When your body temperature is over 98.6o, your body is out of homeostasis
Example: When you are dehydrated, your body is out of homeostasis

3. How do we maintain homeostasis?
Cell Membranes!
Surrounds the outer portion of an animal cell
Is found inside of the cell wall of a plant cell

4. Cell Membrane Structure
Phospholipid- Phosphate and lipid that forms the “wall” portion of the membrane
Small molecules such as H2O and O2 can pass through
Phosphate- Is polar and hydrophilic (water loving)
Lipid- Is non-polar and hydrophobic (water hater)
Protein-Protein portion that forms the “door” portion of the membrane
Allows large molecules (such as Na and K) to pass into or out of the cell

6. Phospholipid Structure
Phosphate-hydrophilic Outside portion of the cell membrane
Lipid-hydrophobic
Inside portion of the cell membrane

7. Complete Catch It Questions 1-2
Comp Book Time!
Complete Catch It Questions 1-2

8. Semi-Permeable Membrane
Cell membrane allows some molecules to enter and others to exit the cell
Keeps unneeded molecules out of the cell
Is also called selectively permeable membrane
Outside of cell
Inside of cell

9. Fluid Mosaic Model Cell membranes are in constant motion
Is called the Fluid Mosaic Model
Are moving to maintain homeostasis
Letting certain molecules in and out as needed

10. How do cells move molecules?
Cells maintain homeostasis by moving molecules in and out of the cell membrane
Passive Transport
Requires no cellular energy (ATP made by the mitochondria)
Example: Osmosis and Diffusion
Active Transport
Requires the usage of ATP
Example: Na/K pumps

11. Concentration Gradient

12. Passive Transport No cellular energy (ATP) is used Diffusion
The movement of molecules from an area of high concentration to low concentration

13. Equilibrium: When the concentration of molecules on both sides of the membrane are equal
No more movement will happen
Molecule of dye
Membrane
Equal on both sides

14. Facilitated Diffusion:
Facilitate- “to help”
Molecules that can not pass through the phospholipid layer pass through proteins
Glucose
Blood sugar

15. Osmosis: The diffusion of H2O across a cell membrane
H2O moves from high concentration to lower concentration
Not a lot of H2O=Lower concentration
A lot of H2O=Higher concentration

16. Just a reminder….. Solute: What is being dissolved
Solvent: What is doing the dissolving
Water is the universal solvent
When making sweet tea-
The water is the solvent
The tea and sugar are the solutes

17. Osmosis creates different conditions for cells Hypotonic:
Hypo= lower
Concentration of solute molecules is lower in the environment than in the cell
H2O moves into the cell and it swells
Eventually the cell will burst if H2O does not move out of the cell (cytolysis)

18. Environment is 90% H2O
90% +10% NaCl= 100%
Solution is 80% H2O
90% +20% NaCl= 100%

19. Hypertonic Hyper= Higher
Concentration of solute molecules is higher in the environment than in the cell
H2O will leave the cell and it will shrink
Example: Dehydration

20. Environment is 80% H2O
80% +20% NaCl= 100%
Cell is 90% H2O
90% +10% NaCl= 100%

21. Isotonic
Iso= equal
The concentration of the solute molecules is equal on both sides of the cell membrane
Cells neither gain nor lose H2O
Cells are in homeostasis

23. Complete Catch It Questions 3-6
Comp Book Time!
Complete Catch It Questions 3-6

24. Cytolysis: Turgor Pressure:
An animal cell in a hypotonic environment will eventually swell and burst
Turgor Pressure:
A plant cell is restricted by the cell wall
A plant cell in a hypotonic environment will stand up to gain access to more sunlight
Cells do not burst due to the cell wall

25. Plasmolysis: When a plant cell is in a hypertonic environment, water leaves the cell and the vacuole shrinks
Plant wilting

26. Active Transport Cellular Energy (ATP) is used
Moving molecules from an area of low concentration to an area of high concentration
Na/K pumps in neurons

27. Endocytosis: Endo= into Cyto= cell
Cell membranes change shape to allow large molecules to enter the cell
Example: cells engulf protein molecules

28. Types of Endocytosis Pinocytosis Pino= Drinking Cyto= Cell
The movement of solutes or fluids into the cell

29. Phagocytosis Phag= to eat Cyto= cell
The movement of large particles or entire organisms into a cell
Example: White Blood Cells (wbc), Amoeba

30. Exocytosis Exo= exit Cyto= cell
Passage of large molecules to the outside of the cell
The cell membrane changes shape
Example: Waste products are secreted into the environment, Golgi Body secretions, Hormones

31. Complete Catch It Questions 7-10
Comp Book Time!
Complete Catch It Questions 7-10

32. Type of cell - ___________
Animal
Type of cell - ___________
8.5% NaCl
hypertonic
Type of solution - _____________
91.5% H2O
out
How will water move? _____
45% NaCl
osmosis
55% H2O
By what process? ______________ in
How will salt move? ______
diffusion
By what process? _______________
shrink in size
What will happen to the cell? _____________
plasmolysis
Biological term - __________________

33. Type of cell - ___________
Plant
Type of cell - ___________
8.5% NaCl
hypotonic
Type of solution - _____________
91.5% H2O in
How will water move? _____
0% NaCl
Distilled water
osmosis
By what process? ______________
100% H2O
out
How will salt move? ______
diffusion
By what process? _______________
swell and become rigid
What will happen to the cell? _____________
turgor pressure
Biological term - __________________