Respuesta :
If I'm right I'd say They control and direct the quantity of food passing through the digestive organs and prevent backward movement of partially digested food. Hope it's helpful.
The sphincter is the voluntary or involuntary closing and opening of a certain tube or tract inside your body. The sphincter of the digestive tract controls the amount of materials going out of the body. Sphincter controls the amount of food that can empty be emptied into the duodenum.