Channel proteins are less selective than carrier proteins, and usually mildly discriminate between their cargo based on size and charge.
A vesicle is a membranous sac—a spherical and hollow organelle bounded by a lipid bilayer membrane.
The blood clotting cascade contains many zymogens.
Similarly, if an individual ate a lot of salty food, their body would work to keep their internal salinity at a safe parameter by filtering out unneeded salts.
The body must maintain proper glucose levels to ensure a person remains healthy.
If blood glucose levels drop too low, the liver converts in the blood to glucose again, raising the levels.