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 primary muscles that function to hold in stool are the internal and external anal sphincters. The internal sphincter is a completely involuntary organ, and as stool passes through this sphincter, the muscle slowly relaxes. The stool then contacts the external sphincter, which is a completely voluntary organ.he primary muscles that function to hold in stool are the internal and external anal sphincters. The internal sphincter is a completely involuntary organ, and as stool passes through this sphincter, the muscle slowly relaxes. The stool then contacts the external sphincter, which is a completely voluntary organ.