A hiatal hernia or failure of the lower esophageal (cardiac) sphincter to close causes the stomach contents to back up into the esophagus. This causes the esophageal wall to have a burning sensation (heartburn) and, in serious cases, bleeding. What causes the burning sensation and bleeding to occur

The hydrochloric acid produced by the stomach for digestion.

Explanation:

Due to the hernia, there is poor sphincter control thus allowing backflow of the acid into the eaophagus

answer; ////increased water pollution; ///////////////////////

endo:

regulates body hormones, aldosterone, vasopressin

neural:

signal, regulates body using electric signals, reflex

endo has to do with hormones; aldosterone and vasopressin are both hormones. i also had this question and got it right : d