What structure prevents reflux of stomach contents?

Lower esophageal sphincter (cardiac sphincter)
prevents reflux of acid stomach contents into the esophagus; note that it does not regulate entry into the stomach. Cardiac Region.
region of the stomach where the contents of the esophagus enter into the stomach.

The main role of dna in the  cell is the long-term storage of information. it is often compared to a blueprint, since it contains the instructions to construct other components of the  cell, such as  proteins  and rna molecules.the main function of rna is to carry information of amino acid sequence from the genes to where  proteins  are assembled on  ribosomes  in the  cytoplasm. mark brainliest, my work is good.