B) Submucosa
Consists areolar connective tissue that binds the mucosa to the muscularis. Contains many blood and lymphatic vessels that receive absorbed food molecules. Extensive network of neurons known as Submucosal Plexus This layer also contains glands and lymphatic tissue.
C) Mucularis
Muscularis of the mouth, pharynx, superior and middle parts of the esophagus contain skeletal muscle producing voluntary swallowing. Skeletal muscle also forms the external anal sphincter permitting voluntary defecation. Smooth muscle for the rest of the tract. Generally, found in 2 sheets: Inner circular and outer longitudinal fibres. Involuntary contractions of the smooth muscle help to break down food, mix it with digestive secretions, and propel it along the tract. Second plexus located b/t the two sheets called Myenteric Plexus .
D) Serosa
Those portions of the GI tract suspend within the abdominopelvic cavity have a superficial layer called Serosa (aka) Visceral Peritoneum . Esophagus lacks a serosa; instead only a single layer of areolar connective tissue called Adventitia forms the superficial layer of this organ.
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