The largest oil spill to occur in the United States so far was the Exxon Valdez spill into Prince William Sound, Alaska, in March 1989. The Exxon Valdez, a medium-sized oil tanker, ran aground on a reef to cause this spill of almost 11 million gallons of crude oil.
Sphincters, composed of skeletal muscles, regulate movement through our digestive and urinary systems, thus, controlling swallowing, defecation and even urination. Skeletal muscle contraction generates heat, which helps to maintain body temperature.
1 The cardia (lower esophageal sphincter), or cardiac sphincter, at the upper portion of the stomach. 2  This sphincter prevents the acidic contents of the stomach from moving upward into the esophagus. 3  The pyloric sphincter, at the lower end of the stomach. The sphincter pupillae, or pupillary sphincter, belonging to the iris in the eye. 2  The orbicularis oculi muscle, a muscle around the eye. 3  The upper and lower oesophageal sphincters. 4  The cardia (lower esophageal sphincter), or cardiac sphincter, at the upper portion of the stomach.