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.
The internal sphincter is a continuation of the detrusor muscle and is made of smooth muscle, therefore it is under involuntary or autonomic control. This is the primary muscle for prohibiting the release of urine. The female or male external sphincter muscle of urethra (sphincter urethrae): located at the bladder's distal inferior end in females and inferior to the prostate (at the level of the membranous urethra) in males is a secondary sphincter to control the flow of urine through the urethra.