Homeostasis

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

4. 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

5. 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 • Lipid- Is non-polar and hydrophobic • 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

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

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

9. 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

10. 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 http://telstar.ote.cmu.edu/biology/MembranePage/index2.html

11. 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

12. Concentration Gradient

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

14. 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

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

16. 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

17. 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 http://www.youtube.com/watch?v=sdiJtDRJQEc&feature=related

18. 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)

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

20. 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

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

22. Isotonic • Iso= equal • The concentration of the solute molecules is equal on both sides of the cell membrane • Cells neither gain or loose H2O • Cells are in homeostasis

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

25. Cytolysis: • 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

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

27. 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

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

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

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

31. 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

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

33. 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 - __________________

34. 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 - __________________