Which nerve is NOT involved in the efferent (motor) swallow reflex?

Correct Answer: B

Rationale: The correct answer is B: vagus. The efferent (motor) swallow reflex involves motor nerves that control swallowing muscles. The vagus nerve (cranial nerve X) is primarily responsible for the afferent (sensory) component of the swallow reflex, while the efferent component is carried out by other cranial nerves such as the glossopharyngeal (IX), facial (VII), and hypoglossal (XII) nerves. Therefore, the vagus nerve is not directly involved in the efferent motor response during swallowing. Trigeminal (V), facial (VII), and hypoglossal (XII) nerves play essential roles in the motor aspects of swallowing, making them incorrect choices.

Correct Answer: C

Rationale: The correct answer is C because 1,25-dihydroxycholecalciferol, the active form of vitamin D, does induce calcium binding protein synthesis in mucosal cells, facilitating calcium absorption. This process occurs in the small intestine. Choices A and B are incorrect because around 30% of calcium is typically absorbed, and active transport of Ca2+ primarily occurs in the upper small intestine. Choice D is incorrect because phosphate does not directly facilitate calcium absorption.

Correct Answer: A

Rationale: The correct answer is A: islets of Langerhans. These clusters of cells in the pancreas are responsible for producing hormones such as insulin and glucagon. They play a crucial role in regulating blood sugar levels. The other choices, B: pancreatic medulla, C: pancreatic cortex, and D: nodules, are incorrect as they do not accurately describe the specific clusters of cells in the pancreas responsible for hormone production. It is important to understand the function and location of the islets of Langerhans to grasp the endocrine role of the pancreas.

Correct Answer: C

Rationale: The correct answer is C: Larynx. The alimentary canal is the digestive tract where food passes through. The larynx is not part of this pathway; it is part of the respiratory system, specifically involved in phonation and protecting the trachea during swallowing. The mouth, pharynx, and esophagus are all part of the alimentary canal, where food is ingested, swallowed, and transported to the stomach for digestion. Therefore, the larynx is the correct answer as it is not part of the digestive process.

Correct Answer: B

Rationale: The correct answer is B: To digest carbohydrates. The stomach primarily digests proteins through the action of pepsin and hydrochloric acid. Carbohydrates are primarily broken down in the mouth by salivary amylase, not in the stomach. Choices A, C, and D are incorrect because the stomach does play a role in digesting proteins, temporarily storing food, and neutralizing alkali from the mouth, respectively.