Final answer:
The function of the muscularis of the GI tract wall is to propel and mix contents, which is achieved through peristalsis and mixing movements of the longitudinal and circular smooth muscles.
Step-by-step explanation:
The statement that the function of the muscularis of the GI tract wall is to both propel and mix the contents of the tract is True.
The gastrointestinal (GI) tract's muscular layer, known as the muscularis externa, is instrumental in facilitating the movement and mechanical digestion of food. It comprises two types of smooth muscle: the longitudinal muscle, which extends along the length of the GI tract, and the circular muscle, which encircles the organs. The orchestration of these muscles supports the process of peristalsis, a wave-like involuntary contraction and relaxation that moves food through the digestive system.
In addition to peristalsis, the muscles also perform mixing movements, like those in the stomach, which further combine and break down the food mechanically, bringing it into better contact with digestive enzymes. These essential muscular actions are central to both the propulsion of digestive content along the tract and mixing to enhance digestion.