Transport Flashcards
Diffusion
higher concentration to low concentration down a concentration gradient
What can diffuse
gasses
liquids
ions in solution
Movement of Particles
Particles move randomly because of the kinetic energy they naturally have
Dynamic Equilibrium
there is no net movement of particles,
Dynamic- particles continue to move
Equilibrium- concentration either side remains the same
Simple Diffusion
Fat-soluble molecules can diffuse through the bilayer
Facilitated Diffusion
Polar molecules are unable to pass through the hydrophobic inside of the phospholipid bilayer,
therefore they require proteins to enable them to pass through the bilayer,
Channel Proteins
used in facilitated diffusion,
each specific protein shape is selective in what it lets through
Aquaporins
specific channel proteins that allow water to move freely from cytoplasm to environment
factors affecting rate of diffusion
membrane thickness,
surface area,
concentration gradient,
partially permeable.
Ficks Law
Rate of Diffusion = (concentraio gradient X surface area) / membrane thickness
Folds
microvilli and gut epithelial cells folds which increase surface area and decreases the diffusion pathway,
Active Transport
low concentraion to high concentration against concentraion gradient with the use of ATP
Osmosis
only refers to the movement of water,
occurs across a semi permeable membrane which has tiny holes in it,
the holes are small enough for water molecules to pass through but larger molecules can not pass through
Water Potential
a measure of the pressure exerted by the movement of water,
Water Potential Units
kPa
Kilo Pascalds
High Water Potential
more water can move
Low Water Potential
less water can move
Water Potential of 0 kPa
Pure water has the highest water potential
Water Potential of -8 to -10 kPa
the more dissolved solutes in the water the less water is able to move and the lower (more negative) its water potential is
Movement of Water
water will move from high water potential to low water potential,
less negative —-> more negative
Water Potential fall
a solutes water potential will fall as solutes are added because water molecules will cluster around the solute molecules
Hypotonic
less solute concentration, high water potential
water will move into the cell causing it to expand and burst
Isotonic
same water potential,
the same amount of water enters the cell as what moves out so the cell is not damaged
Hypertonic
more solute concentration, lower water potential
wtaer will mover out of the cell causing it to shrivel up
Net Movement of Water
A net movement of water molecules from a region of high water potential to a region of lower water potential through a selective semi permeable mebrane
Co Transport
sodium ions are pumped out of the cell (high concentration —> low concentration),
sodium ions enter from the lumen of the small intestine therefore glucose will then enter the cell,
glucose builds up in the cell and then diffuses into the blood
