1 The pancreas is an abdominal gland situated behind the stomach in the upper abdomen.  The main function of the pancreas is to secrete hormones and enzymes that help with digestion and regulate blood sugar (glucose) metabolism.
See also: List of tram and light rail transit systems. The Shanghai Metro is the longest metro system by route length. The Beijing Subway is the metro system with the highest ridership. The New York City Subway has the most stations.
The metro network is planned to be expanded up to a length of 877km with 22 lines. The annual ridership of the metro in 2012 was 2.276 billion. Beijing Subway, China. Beijing Subway, Chinaâs oldest metro system, currently ranks as the worldâs third longest subway system comprising of 17 operatinglines spanning a total length of 456km.