Describe the role of the anal sphincter in waste elimination.

The anal sphincter plays a crucial role in waste elimination by regulating the release of feces from the rectum through the anus. Comprising two muscular rings, the inner involuntary (smooth) sphincter and the outer voluntary (skeletal) sphincter, it maintains continence between bowel movements. The involuntary sphincter remains contracted to prevent accidental leakage, while the voluntary sphincter allows conscious control over defecation. During bowel movements, the voluntary sphincter relaxes, enabling the expulsion of feces. This coordinated action ensures controlled waste elimination, preventing involuntary leakage and providing individuals with the ability to choose an appropriate time for defecation.