Where does the digestion of proteins begin?

Correct Answer: B

Rationale: The correct answer is B: Stomach. Protein digestion begins in the stomach where the enzyme pepsin is secreted. Pepsin breaks down proteins into smaller peptides. This process is aided by the acidic environment of the stomach. In contrast, the mouth primarily starts the digestion of carbohydrates through the enzyme salivary amylase. The small intestine is where further breakdown and absorption of nutrients occur, not the initial digestion of proteins. The large intestine is mainly responsible for absorbing water and electrolytes, not digestion.

Correct Answer: D

Rationale: The correct answer is D because parasympathetic stimulation causes the contraction of the gall bladder. This is due to the release of acetylcholine which stimulates the gall bladder to contract and release bile into the duodenum to aid in digestion. Choices A, B, and C are incorrect as parasympathetic stimulation does not cause constriction of the pylorus, contraction of the internal anal sphincter, or contraction of the external anal sphincter.

Correct Answer: B

Rationale: The correct answer is B: congenital heterotopia. This is because the presence of small intestinal type epithelium in the gastric mucosa indicates ectopic tissue that is not normally found in the stomach. This condition is known as congenital heterotopia, where tissues from one organ are found in another due to developmental abnormalities. A: Chronic gastritis would not lead to the presence of small intestinal type epithelium in the gastric mucosa. C: Precancerous dysplasia refers to abnormal cellular changes that can progress to cancer but does not explain the presence of small intestinal type epithelium. D: Metastatic carcinoma would involve the spread of cancer cells from another primary site, not the presence of ectopic tissue.

Correct Answer: B

Rationale: Step-by-step rationale for why choice B is correct: 1. Carcinoid tumors can produce systemic symptoms due to the release of bioactive substances. 2. Metastasis to the liver can lead to the production of systemic symptoms like flushing and diarrhea. 3. This systemic symptom production is a characteristic feature of carcinoid tumors. 4. Choice B accurately describes the biologic nature of carcinoid tumors in relation to systemic symptoms. Summary of why other choices are incorrect: A: Carcinoid tumors can be malignant and produce systemic symptoms, so they are not always benign. C: Carcinoid tumors originating in the appendix are typically associated with a more favorable prognosis. D: Jejunal ulceration due to gastrin elaboration is more commonly seen in gastrinomas, not carcinoid tumors.

Correct Answer: C

Rationale: Step-by-step rationale: 1. Saliva is slightly acidic, not alkaline. 2. The secretion of saliva is under both neural and hormonal control. 3. Saliva contains enzymes that digest carbohydrates, not proteins. 4. Therefore, choice C is correct as it provides accurate information about the alkalinity of saliva.