Are surfactants amphipathic?

It is short for surface active agent. They are large molecules that are partially nonpolar and partially polar. Polar interacts with water...as nonpolar interacts with grease or dirt.

A substance that tends to reduce the surface tension of a liquid in which it is dissolved.

Yes they are.The two fatty acid tails of the molecule are hydrophobic(repel water) but the phosphate head(negatively charged) is hydrophilic (attached to water)thus making it amphipathic.In...

prevent each alveolus from collapsing as air moves in and out during respiration

Thyroxine