▁function . ▁Connection ▁to ▁the ▁central ▁nerv ous ▁system ▁also ▁means ▁that ▁signals ▁from ▁outside ▁of ▁the ▁dig est ive ▁system ▁can ▁be ▁relay ed ▁to ▁the ▁dig est ive ▁system : ▁for ▁instance , ▁the ▁sight ▁of ▁appe aling ▁food ▁stim ul ates ▁secret ion ▁in ▁the ▁st om ach . ▁ ▁Ne uro trans mit ters ▁The ▁enter ic ▁nerv ous ▁system ▁makes ▁use ▁of ▁over ▁ 3 0 ▁different ▁ne uro trans mit ters , ▁most ▁similar ▁to ▁those ▁of ▁the ▁C NS ▁such ▁as ▁ac et yl ch oline , ▁dop am ine , ▁and ▁ser ot on in . ▁More ▁than ▁ 9 0 % ▁of ▁the ▁body ' s ▁ser ot on in ▁lies ▁in ▁the ▁gut ; ▁as ▁well ▁as ▁about ▁ 5 0 % ▁of ▁the ▁body ' s ▁dop am ine , ▁which ▁is ▁currently ▁being ▁studied ▁to ▁further ▁our ▁understanding ▁of ▁its ▁utility ▁in ▁the ▁brain . ▁The ▁heavily ▁studied ▁ne urope pt ide ▁known ▁as ▁subst ance ▁P ▁is ▁present ▁in ▁significant ▁levels ▁and ▁may ▁help ▁facil itate ▁the ▁production ▁of ▁sal iva , ▁smooth ▁mus cle ▁contra ctions , ▁and ▁other ▁t issue ▁responses . ▁ ▁Re cept ors ▁Since ▁many ▁of ▁the ▁same ▁ne uro trans mit ters ▁are ▁found ▁in ▁the ▁E NS ▁as ▁the ▁brain , ▁it ▁follows ▁that ▁my enter ic ▁neur ons ▁can ▁express ▁re cept ors ▁for ▁both ▁pe pt ide ▁and ▁non - pe pt ide ▁( am ines , ▁am ino ▁ac ids