Final answer:
True. The GI tract from the esophagus through the large intestine is a tube composed of four concentric layers called tunics.
Step-by-step explanation:
True. The GI tract, which includes the esophagus through the large intestine, is indeed a tube composed of four concentric layers called tunics. These layers are the mucosa, submucosa, muscularis externa, and serosa. The mucosa is the innermost layer and is responsible for secretion and absorption. The submucosa contains blood vessels and lymphatic tissue. The muscularis externa consists of two layers of smooth muscle that help with peristalsis. And finally, the serosa is the outermost layer that protects and supports the GI tract.