Which of following processes is the function of the smooth muscle layer of the digestive system? a) Ingestionb) Secretionc) Mixing and propulsiond) Absorptione) None of these choices

The correct answer is: e) None of these choices

Beneath the epithelium layer in digestive tract (which is responsible for absorbtion) is the muscularis mucosa. Muscularis mucosa consists of layers of smooth muscle which can contract to change the shape of the lumen. The submucosa surrounds the muscularis mucosa and beneath it is another muscle layer called muscularis externa. Muscularis externa is composed of circular and longitudinal layers of muscle fibres that are responsible for the mechanical breakdown and peristalsis (pulsative movement) of the food within the lumen.

The answer is "none of the above".

The smooth muscle is responsible for movement of food by peristalsis and mechanical digestion by segmentation.