Final answer:
The correct sequence of layers of the GI tract from most visceral to most parietal is mucosa : submucosa : muscularis : serosa.
Step-by-step explanation:
The correct sequence of layers of the GI tract, from most visceral to most parietal, is mucosa : submucosa : muscularis : serosa.
The mucosa is the innermost layer surrounding the lumen or open space within the organs of the GI tract. It consists mainly of the epithelium, which can secrete digestive enzymes and mucus and absorb nutrients and water.
The submucosa lies immediately beneath the mucosa and is a broad layer of dense connective tissue connecting the mucosa to the muscularis. It contains blood and lymphatic vessels and submucosal glands.
The muscularis (also called the muscularis externa) is the third layer and is responsible for the mechanical digestion and movement of food along the canal. In the small intestine, it is made up of an inner circular layer and an outer longitudinal layer of smooth muscle.
The serosa is the outermost layer of the GI tract and consists of connective tissue. It separates the organs from surrounding cavities and tissues.