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
exists and is an alternate of . EP stands for extended play as EP records are longer than original single 45 records, usually containing 4 tracks. Artists usually release an EP before the full album to give the fans a taste of what is coming. The EP may include anywhere from 2 to 10 songs depending on the length of the full album. A good example of an EP containing 4 tracks was the Beatles' 'Twist and Shout (EP)'. The EP format is also used as a low-cost way of showcasing new artists. Historically, EP records were often similar to seven inch single records but played at 33 1/3 rpm rather than 45 rpm.