explain in terms of physiology why you have increased salivation shortly before you vomit?

Answer 1

it may be a defense mechanism by your body to lubricate the parts. I really don't know, can you tell that was bullshit?

Answer 2

Stomach contents contain molecules (acids, mostly) that were not present when one injested the food; starches are basically the only things our mouths and upper end of the digestive tract are supposed to come in contact with besides whole chunks of food; we know this because it is the only thing we can digest thus far in the system.
Stomachs have digested the food into things our throat/mouth was not made to digest. The molecules (mostly acidic) would react harshly to our throat/mouth and undergo chemical reactions that were not meant to happen there.
Hence, our body undergoes a defense mechanism, whereby our saliva creates a protective coating that is likely inert to the chemicals - the harsh chemical reactions that would otherwise occur are innoculated because of our saliva.

It should also be noted that you should not brush your teeth for 15 minutes post-vomiting because the toothpaste ALSO undergoes a chemcial reaction with the acids and that corrodes your teeth.

Answer 3

Saliva helps to neutralize the acids from the stomach that may decay teeth.