28 terms

Membranes

STUDY
PLAY

Terms in this set (...)

Cell Membrane
A thin, flexible barrier around a cell; regulates what enters and leaves the cell
Structure of Membrane
-two layers of phospholipid molecules on both side
polar phosphate head (hydrophillic) and non-polar fatty acid tail (hydrophobic)
Phospholipid Bilayer
Plasma membrane layers composed of phospholipid molecules arranged with polar heads facing the outside and nonpolar tails facing the inside.
Selective Permeability
(the ability to allow some sub. to cross the plasma membrane more easily) A property of biological membranes that allows some substances to cross more easily than others.
Passive Process
No additional energy input is reqd
movement into and out of cells
the net movement of water molecules through a selectively permeable membrane from an area of higher water concentration (low solutes) to low water concentration (high solutes) is osmosis
LOW TO HIGH
Active Process
Process of membrane transport that has movement of a substance up concentration gradient
HIGH TO LOW
Diffusion
Movement of molecules from an area of higher concentration to an area of lower concentration.
Both osmosis and faciliated diffusion are a type of this
Simple Diffusion
Exchange of both oxygen and carbon dioxide through the respiratory membrane occurs by
the movement of particles from a higher concentration to a lower concentration
nonpolar and lipid-soluble substances diffuse directly through the lipid bilayer.
unassisted movement to equalize
Facilitated Diffusion
typically across capillary walls
uses integral membranes
moves large charged hydrophobic cells
Osmosis
Diffusion of water across a selectively permeable membrane
Diffusion of molecules through a semipermeable membrane from a place of higher concentration to a place of lower concentration until the concentration on both sides is equal.
Hydrostatic Pressure
Pressure exerted by a volume of fluid against a wall, membrane, or some other structure that encloses the fluid.
Osmotic Pressure
pressure that must be applied to prevent osmotic movement across a selectively permeable membrane
Osmolarity
Total concentration of solute particles in a solution
Tonicity
ability of a solution to alter a cells water volume
Isotonic Solution
concentration outside the red blood cell equals the concentration inside the red blood cell. equal to cytosol
Hypotonic Solution
Solution with higher concentration than cytosol
Hypertonic Solution
Solution with lower concentration than cytosol
Hydrophillic
water attracted
this term literally mens "water loving"; it refers to substances that are made of polar molecules like water
Hydrophobic
water fearing
Having an aversion to water; tending to coalesce and form droplets in water.
Filtration
The movement of a substance across a membane via pressure. .
Vesicular Transport
Transport of large particles and macromolecules across plasma membranes
Na/K Pump
allows movement of the two between the cellmembranes
Active transport (uses ATP) to move 3 Na (in) and 2 K (out) against their concentration gradient
Endocytosis
A process in which a cell engulfs extracellular material through an inward folding of its plasma membrane.
Phagosytosis
Food particles are engulfed and ingested by the cell
Pinocytosis
A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes.
Exocytosis
Process by which a cell releases large amounts of material
Polar
Molecule with partial charges. Mixes with water. 2 sides
Non-Polar
Molecule that is uncharged