Simple Diffusion - net movement of particles from one area of high concentration to an area of lower concentration
Diffusion
Passive (requires no energy) movement of particles in fluids
Molecules move randomly but most often move into available space until it is evenly distributed (equilibrium is achieved)
Net movement happens down a concentration gradient; from lower concentration to high concentration
Substances diffused in and out of bodily tissues
CO2
O2
Urea
Concentration Gradient
Linked to the difference in concentration between 2 areas
The higher the difference in concentration between the 2 areas, the bigger the concentration gradient so the faster the rate of diffusion
Temperature
The higher the temperature the faster the rate of diffusion
Membrane Surface Area
The larger the surface area of a membrane is the larger space in which the diffusing substance can enter the membrane
The larger the membrane surface area the faster the rate of diffusion
Thickness of Membrane
The thicker the membrane the slower the rate of diffusion
Channel or Carrier Proteins
The higher the concentration gradient the faster the rate of diffusion of facilitated diffusion until an equilibrium is achieved and then the rate will level out as the low concentration area has been filled
The more proteins the faster the rate of diffusion
Size and Shape of Molecules
Smaller molecules diffuse faster than larger molecules at a given temperature
More energy is needed to move larger molecules down the concentration gradient than a smaller molecule
