What do sphincter muscles do? a. Trigger hormone release. b. Control peristalsis. c. Secrete digestive juices into the GI tract. d. Mix food with saliva. e. Regulate the flow of food particles along the GI tract.

Answer is E.

Explanation:

Generally, sphincter are circular or ring - shaped muscles, surrounding the natural opening in the body. They control the movement of substances by opening and closing through expansion and contraction.

There are many sphincter in the body, examples are

* Cardiac sphincter ... found at the upper area or portion of the stomach.

* Pupilary sphincter ... found in the iris of the eye.

* Glisson's sphincter ... controlling the secretion of the gall bladder, pancrease and the liver.