Digestion and the Cell Membrane

Flashcards about the cell membrane and the digestive system

Cell Membrane

Controls the movement of molecules in and out of the cell; is 'semi-permeable'

Semi-permeable

Some small molecules can pass directly through the membrane (ex. H2O, O2, CO2)

Fluid mosaic

Flexible and made of many pieces.

Phospholipid Bilayer

A bilayer with protein channels embedded in it.

Phospholipids

Spontaneously form a bilayer in an aqueous environment.

Hydrophilic

Polar heads (water loving)

Hydrophobic

Fatty acid tails (water hating)

Cholesterol

A major membrane lipid in animals that helps to make the membrane less fluid.

Carbohydrate chains

Often function as cell identification markers, allowing cells to identify other cells.

Absorption in the Small Intestine

Nutrients are absorbed into the circulatory system from the mucosa of the jejunum and ileum (small intestine)

Villi and microvilli

Increase surface area in the small intestine

Lacteals

Fats are absorbed into the lacteals of the lymphatic system.

Passive Transport

The movement of materials across a cell membrane without the use of energy.

Diffusion

Materials follow a concentration gradient from high to low concentration until they are evenly distributed

Osmosis

The diffusion of water across a selectively permeable membrane from high to low concentration

Facilitated Diffusion

Diffusion of materials across a membrane through transport proteins embedded in the membrane

Active Transport

The transportation of materials across a cell membrane, from an area of low concentration to an area of high concentration, using energy from the cell