Facilitated diffusion is a passive diffusion process involving the transportation of large or polar molecules and ions across the cell membrane (which they cannot normally pass through) with the help of transport proteins. Because facilitated diffusion is a form of passive transport, no energy is required for the movement of a solute from a high solute concentration area to a low solute concentration area.
Osmosis is the movement of water molecules from a high water concentration area to a low water concentration area across …show more content…
Carrier proteins are proteins that carry molecules across the cell membrane from areas of high concentration to areas of low solute concentration. In facilitated diffusion, carrier proteins move molecules that can not pass through the membrane by means of simple diffusion (such as polar molecules and ions) by carrying them across and changing their shape in order to allow the translocation of solutes.
A solution that is hypertonic contains a higher concentration of solutes than water. Conversely, a solution that is hypotonic contains a higher concentration of water than solutes. An isotonic solution is one which has a relatively equal amount of water and solute. This is important in osmosis because the state of the solutions outside and inside the cell determine the movement of the water. For example, if the cell is placed in a hypertonic solution, the water will rush out of the cell and cause it to shrink because the water moves from high concentration (inside the cell) to low concentration (the solution outside the …show more content…
Within the alveoli, the concentration of O2 is much higher than its concentration in the blood. This causes the O2 to move from the alveoli and into the bloodstream due to the concentration gradient. Additionally, the blood has a higher concentration of CO2 whereas the alveoli have a lower concentration of CO2. This causes the CO2 to move from the bloodstream to the alveoli, where it can be released.
An example of facilitated diffusion can be seen in the movement of glucose across the plasma membrane of red blood cells in order to be used as energy. The receptor is very sensitive and only glucose is accepted for transportation by the carrier protein. Active transport is a major component of solute regulation that maintains the internal environment of cells. An example of this regulation can be seen in the amounts of potassium and sodium that are present inside and outside the cell. Active transport allows these molecules to move across the membrane with the concentration gradient (from high concentration to low concentration) and against the concentration gradient (from low to high concentration) as is required by the