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 Urine is stored in the bladder. 2  The sphincter muscles relax. 3  The bladder muscle (detrusor) contracts. 4  The bladder is emptied through the urethra and urine is removed from the body. The primary receptors in the bladder neck are alpha-adrenergic. 2  Sympathetic stimulation of these alpha receptors, via fibers in the hypogastric nerve, contributes to urinary continence. 3  The external sphincter is histologically different from the detrusor and internal sphincter. 4  It is striated muscle.