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?

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

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.

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

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)

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…

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…

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…

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

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

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.

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…

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

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

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.