2. Homeostasis
To maintain and regulate constant or stable internal conditions.
What does your body need to regulate?
Temperature pH
concentration of other materials and nutrients
What organelle helps maintain homeostasis?

3. Cell Membrane
Selective Permeability: some substances can cross it freely, others must move through a gate
Passive Transport
Active Transport

4. Cellular Transport
Passive Transport requires no extra energy by the cell
molecules move from areas of high concentration to low concentration
down the concentration gradient.
Active Transport requires extra energy (ATP) to bring materials into or expel materials out of the cell
molecules move from low concentration to high concentration
against the concentration gradient.

5. Examples of Transport Passive Transport Diffusion Osmosis
Facilitated Diffusion
Active Transport
Molecular Pumps
Exocytosis
Endocytosis

6. Water Transport Vocab.
Solute – what gets dissolved (Ex. Lemonade powder)
Solvent – does the dissolving (Ex. Water)
Solution – uniform mixture of two or more substances (Ex. Lemonade)
Concentration – amount of solute dissolved in solvent (Ex. How sweet your lemonade is)

7. Passive Transport: Diffusion
Molecules spread across a membrane so they are concentrated equally on either side
Molecules move down a concentration gradient, from high concentration to low concentration
Ex. Oxygen and Carbon Dioxide
Over time…

8. Passive Transport: Facilitated Diffusion: “Help” difussion
Transport protein: acts as a channel to help molecules cross the phospholipid bi-layer
Molecules move down a concentration gradient
from high concentration to low concentration
Ex. Glucose/sugar, sodium/salt
Over time…

9. Passive Transport: Osmosis
diffusion of water across the cell membrane
Water molecules move down a concentration gradient
from high concentration to low concentration
Over time…

10. Passive Transport: Osmosis
Hypertonic solutions: water concentration is below what is found in a cell’s cytoplasm.
Water will tend to move out of the cell, down its concentration gradient  Cell shrivels
Hypotonic solutions: water concentration is above what is found in a cell’s cytoplasm.
Water will tend to move into a cell, down its concentration gradient  Cell swells
Isotonic solutions: identical water concentrations to what is found in a cell’s cytoplasm  Cell stays the same

11. Passive Transport: Osmosis
Hypertonic
Hypotonic
Isotonic
H2O
H2O
H2O
H2O
H2O
H2O
Cell stays the same
Cell shrivels
Cell swells

12. Active Transport
Some molecules have to be pushed “uphill,” against a concentration gradient.
substances are moving from an area of low concentration to an area of high concentration
Other substances are too big to move through a protein channel, and have to be enveloped by the cell or excreted by the cell.
This is accomplished by either endocytosis or exocytosis.

13. Active Transport: Molecular Pumps
cell uses energy to pump molecules across the membrane through a protein channel.
allows cell to concentrate key molecules within the cell, or remove waste from the cell.
Ex. Calcium (Ca2+), potassium (K+), chlorine (Cl-) and sodium (Na+) = ions (charged particles)
ENERGY
Over time…

14. Active Transport: Endocytosis
A cell uses energy to import large amounts of materials INTO the cell using a vesicle
Ex. White blood cells engulf bacteria to fight infection

15. Active Transport: Exocytosis
A cell uses energy to export large amounts of materials OUT OF the cell using a vesicle
Ex. Nerve cells release neurotransmitters to pass signals to the brain

16. Practice Time! Type of Transport Passive/Active
Ex. of what is being moved
How it helps maintain homeostasis
Facilitated Diffusion
Regulates blood sugar
Active
Neurotransmitters
Endocytosis
Captures bacteria
Passive
Controls blood pressure by regulating blood volume
O2 and CO2
K+, Na+, Ca2+, Cl-
Muscle contractions and nerve signal conduction
Have students fill this chart in (the best that they can) and go over.