A. Gastrin: G cells secrete gastrin, a hormone that stimulates parietal cells to produce hydrochloric acid and promotes gastric motility. It is released in response to food components like peptides, caffeine, and a rise in pH.
B. Pepsin: Pepsin is an enzyme that digests proteins, but it is secreted as pepsinogen by chief cells, not G cells.
C. Ghrelin: Ghrelin is a hunger-stimulating hormone, secreted primarily by cells in the stomach fundus, not by G cells.
D. Hydrochloric acid: Hydrochloric acid is secreted by parietal cells, not G cells.

A. Stomach: The stomach mixes the food with gastric juices, converting the solid bolus into a semi-liquid substance called chyme.
B. Small intestine: The small intestine receives chyme but does not liquefy the bolus.
C. Mouth: The mouth forms the bolus through mastication and saliva, but it does not produce chyme.
D. Esophagus: The esophagus only transports the bolus via peristalsis and plays no role in liquefying it.

A. Peptides: Peptides in the stomach stimulate G cells to release gastrin, which enhances gastric secretion.
B. Distention: Stretch receptors in the stomach wall respond to distention and activate gastric secretions via reflexes.
C. Low acidity: A rise in pH (low acidity) following food entry triggers gastrin release.
D. Carbohydrates: Carbohydrates do not significantly stimulate gastric secretions; proteins are the primary stimulus during the gastric phase.

A. Store fat-soluble vitamins: Hepatocytes store vitamins A, D, E, and K.
B. Detoxify toxic chemicals: Hepatocytes metabolize and detoxify substances like drugs and alcohol.
C. Process nutrients: They metabolize carbohydrates, lipids, and proteins, modifying absorbed nutrients.
D. Produce digestive enzymes: Hepatocytes do not produce digestive enzymes; that is the role of the pancreas and other gastrointestinal organs.

A. The voluntary phase of swallowing takes place within the mouth: The oral phase is under voluntary control and involves tongue movement to push the bolus to the oropharynx.
B. The epiglottis assists in propelling food into the trachea: This is incorrect. The epiglottis prevents food from entering the trachea by covering the glottis during swallowing; it does not propel food.
C. The involuntary portion of swallowing takes place in the pharynx: After the oral phase, swallowing becomes involuntary, involving reflexive contractions of pharyngeal muscles.
D. The mouth, pharynx and esophagus all take part in swallowing: All three structures are involved in the three phases of deglutition: oral, pharyngeal, and esophageal.

A. Cephalic: The cephalic phase occurs before food enters the stomach, triggered by sight, smell, or thought of food, and stimulates gastric secretion via the vagus nerve.
B. Gastric: The gastric phase begins when food enters and stretches the stomach, triggering myenteric and vagovagal reflexes that stimulate acid and enzyme secretion.
C. Intestinal: The intestinal phase involves chyme entering the duodenum, which moderates gastric activity, mostly inhibitory.
D. Gastrointestinal: “Gastrointestinal” is a general term and not one of the specific phases of gastric secretion.
E. Mesenteric: “Mesenteric” refers to the mesentery (tissue supporting the intestines), not a phase of digestion.

A. Keratinized; lingual papillae: The dorsal surface of the tongue is lined with keratinized stratified squamous epithelium, especially in areas subject to friction, and contains lingual papillae that house taste buds.
B. Keratinized; lingual frenulum: The lingual frenulum is the fold under the tongue, not a bump or papilla.
C. Nonkeratinized; lingual papillae: The top of the tongue is typically keratinized, not nonkeratinized, due to exposure to friction.
D. Nonkeratinized; tonsils: Tonsils are not part of the tongue's surface epithelium and don’t contain taste buds.
E. Nonkeratinized; vallate papillae: Vallate papillae are a type of lingual papillae, but the overall surface is keratinized, not nonkeratinized.

A. Intrinsic salivary gland: This is a general category, not a pair of specific glands, so it doesn't answer the two-part question.
B. Lingual; labial: Both lingual and labial glands are intrinsic (minor) salivary glands.
C. Submandibular; lingual: The submandibular gland is one of the major extrinsic salivary glands, while lingual glands are minor intrinsic glands located in the tongue.
D. Submandibular; sublingual: Both are extrinsic salivary glands.
E. Sublingual; parotid: Both are extrinsic glands; the parotid is the largest.
F. Lingual; sublingual: Lingual is intrinsic; sublingual is extrinsic, so the order here is reversed.

A. The gastrocolic reflex: Triggered by food entering the stomach, it stimulates mass movement in the colon.
B. The duodenocolic reflex: Triggered by chyme entering the duodenum, this reflex stimulates colon contractions.
C. Chyme filling the duodenum: This activates the duodenocolic reflex, promoting mass movement.
D. Chyme filling the stomach: This activates the gastrocolic reflex.
E. The colorectal reflex: This reflex is involved in the defecation process-it responds to rectal filling, not in initiating mass movement in the colon. It is not a trigger for mass movement.

A. Terminal sulcus: This is a V-shaped groove on the tongue that marks the division between the anterior and posterior tongue-not related to tongue mobility.
B. Lingual frenulum: This is a fold of mucous membrane under the tongue that may be too short or tight in some children (ankyloglossia or “tongue-tie”), limiting movement. Surgery may involve cutting this to free the tongue.
C. Uvula: The uvula is part of the soft palate and plays a role in speech and swallowing, not tongue movement.
D. Palatine tonsils: These are lymphatic tissues in the oropharynx and have no role in tongue movement.