ɪn hjˈuːmənz ænd mˈɛni ˈʌðɚɹ ˈænɪməlz, hˌaɪdɹəklˈoːɹɪk ˈæsɪd ɪz ɐ pˈɑːɹt ʌvðə ɡˈæstɹɪk ˈæsɪd sᵻkɹˈiːɾᵻd wɪðˌɪn ðə stˈʌmək tə hˈɛlp hˈaɪdɹəlˌaɪz pɹˈoʊtiːnz ænd pˌɑːlɪsˈækɑːɹɹˌaɪdz, æz wˈɛl æz kənvˈɜːɾɪŋ ðɪ ɪnˈæktɪv pɹˈoʊˈɛnzaɪm, pˈɛpsɪnədʒən ˌɪntʊ ðɪ ˈɛnzaɪm, pˈɛpsɪn.
In humans and many other animals, hydrochloric acid is a part of the gastric acid secreted within the stomach to help hydrolyze proteins and polysaccharides, as well as converting the inactive pro-enzyme, pepsinogen into the enzyme, pepsin.