1. Cell Transport

2. Homeostasis samestanding homeo = samestasis = standing Homeostasis is the relative constancy of the internal fluid environment relative to the outside environment.

3. Fishbowl model Fish are like the cells of the [multicellular] body. FishbowlHuman Body Function WaterBody fluid Internal environment Glass bowlSkin Barrier (internal vs. external) FishCellsStay alive Air pumpLungs Keep O 2 level constant (high) FilterKidneys Keep nitrogen wastes constant (low) HeaterMuscles Keep temperature constant (high) FeederDigestive system Keep nutrient levels contant (high) Everything working together Relatively constant conditions

4. Negative Feedback A regulatory mechanism in which a 'stimulus' causes an opposite 'output' in order to maintain an ideal level of whatever is being regulated. Room Temperature Drops Thermometer Registers Thermostat Kicks In Furnace Turns On Body Temperature Drops Nerve Receptors Registers Brain Responds Muscles Shiver

5. Positive Feedback The output enhances or exaggerates the original stimulus

6. Cell Membrane One way in which the cell maintains homeostasis is the cell membrane. The cell membrane allows some materials into the cell but not others. Acts as a gatekeeper.

7. Passive Transport Substances move from higher concentration to lower concentration in passive transport.

8. Diffusion Small, nonpolar molecules can cross the cell membrane. Oxygen tends to be higher outside the cell. Carbon dioxide tends to higher inside the cell.

9. Osmosis Diffusion of water or another solvent across the cell membrane. Solvent: that which dissolves Solute: the dissolved substance. In a solution of sugar water, which is the solute and which is the solvent? When a painter cleans his brushes, what is the solvent and what is the solute?

10. Effects of Osmosis

11. Active Transport This kind of transport requires energy to move substances against their concentration gradient. Pumps: and vesicles facilitate this: What is the structure of the vesicle membrane?

12. Vocabulary Review 1.Homeostasis 2.Positive Feedback 3.Negative Feedback 4.Polar Molecules 5.Diffusion 6.Osmosis 7.Passive Transport 8.Active Transport 9.Solute 10.Solvent 11.Concentration Gradient pg177 Q1-4 & pg183 Q1-4