The functions of saliva include the following except:

Correct Answer: C

Rationale: The correct answer is C: Digestion of lipids is not a function of saliva. Saliva primarily aids in cleaning the mouth by washing away food particles, killing bacteria with its antibacterial properties, and facilitating speech by lubricating the mouth and throat. Digestion of lipids primarily occurs in the small intestine with the help of enzymes like lipase. Salivary amylase, found in saliva, assists in breaking down carbohydrates, not lipids. Therefore, digestion of lipids is not a function of saliva.

Correct Answer: B

Rationale: The correct answer is B: Diseases of the inner ear. Vomiting is primarily controlled by the vomiting center in the brainstem, which responds to various stimuli such as irritation of the duodenal mucosa (Choice A), microbial toxins in the blood (Choice C), and severe exercise (Choice D). Diseases of the inner ear do not directly trigger the vomiting reflex, making Choice B the correct answer.

Correct Answer: A

Rationale: The correct answer is A: upper gastrointestinal bleeding. Melena is black, tarry stool resulting from the digestion of blood in the gastrointestinal tract. This typically occurs in the upper GI tract due to the longer transit time, allowing the blood to be digested. Lower GI bleeding usually presents as bright red blood in the stool or maroon-colored stool. Therefore, melena is a specific indicator of upper GI bleeding. Choices B, C, and D are incorrect because melena specifically points to upper GI bleeding, not lower GI bleeding or both.

Correct Answer: B

Rationale: Certainly! The correct answer is B: Cholecystokinin (CCK) stimulates the contraction of the gallbladder. This hormone is released from the duodenum in response to the presence of fats and proteins in the small intestine. Its main function is to signal the gallbladder to contract and release bile into the duodenum to aid in the digestion and absorption of fats. A: CCK is not secreted from the jejunum but from the duodenum. C: CCK does not inhibit stomach motility; instead, it enhances the release of digestive enzymes and bile. In summary, choice B is correct as it accurately reflects the role of CCK in stimulating gallbladder contraction, while choices A and C are incorrect based on the functions of CCK in the digestive system.

Correct Answer: C

Rationale: The correct answer is C because saliva does not help in dental caries by increasing acidity; in fact, saliva helps neutralize acids and remineralize teeth. A: Saliva does help in articulation by lubricating the mouth. B: Saliva helps in swallowing by moistening food. D: Saliva contains lysozymes that kill microorganisms, aiding in oral hygiene.