1 Pepsin is the main gastric enzyme. 2  It is produced by the stomach cells called chief cells in its inactive form pepsinogen, which is a zymogen. 3  Pepsinogen is then activated by the stomach acid into its active form, pepsin.
Single (music) In music, a single, record single or music single is a type of release, typically a song recording of fewer tracks than an LP record, an album or an EP record. This can be released for sale to the public in a variety of different formats. In most cases, a single is a song that is released separately from an album, although it usually also appears on an album. Typically, these are the songs from albums that are released separately for promotional uses such as digital download or commercial radio
Woman was the first single released after Lennon's death, and the second to be taken from Double Fantasy. It was issued on 12 January 1981 in the United States, and four days later in the United Kingdom, with Yoko Ono's song Beautiful Boys as its b-side.