During the cephalic phase of gastric secretion,

Correct Answer: D

Rationale: Step 1: The cephalic phase occurs before food enters the stomach, triggered by the sight, smell, or thought of food. Step 2: The vagus nerve sends signals to the stomach to prepare for food digestion during this phase. Step 3: Increased flow of action potentials along the vagus nerve stimulates gastric glands to secrete gastric juice. Step 4: Therefore, choice D is correct as it accurately describes the physiological response during the cephalic phase. Summary: Choices A and B are incorrect as they do not align with the physiological processes during the cephalic phase. Choice C is incorrect because distention of the stomach triggers the gastric phase, not the cephalic phase.

Correct Answer: C

Rationale: The correct answer is C because most ingested food molecules are large and need to be broken down into smaller molecules for absorption. Digestion involves the breakdown of complex nutrients into simpler forms that can be absorbed by the body. Choice A is incorrect because digestive enzymes can work on a variety of substrates, not necessarily requiring a variety. Choice B is incorrect as digestion is not primarily aimed at balancing the diet but rather extracting nutrients. Choice D is incorrect as digestion primarily occurs in the stomach and small intestine, not specifically to prevent disorders of the intestine.

Correct Answer: C

Rationale: The correct answer is C: an anticholinergic medication. Anticholinergic medications inhibit the action of acetylcholine, a neurotransmitter responsible for stimulating intestinal motility. By blocking acetylcholine, anticholinergics can effectively immobilize the intestines during surgery. Choice A (a cholinergic medication) would have the opposite effect by stimulating intestinal motility. Choice B (an antiadrenergic medication) is not directly related to immobilizing the intestines. Choice D is incorrect as only option C is the most effective at achieving intestinal immobilization.

Correct Answer: A

Rationale: The correct answer is A: esophagus. The esophagus is a muscular tube that carries food from the mouth to the stomach through a process called peristalsis. It is lined with muscles that contract to push food downward. The trachea (B) is responsible for breathing, not digestion. The nasopharynx (C) is part of the respiratory system. The epiglottis (D) is a flap of tissue that prevents food from entering the trachea during swallowing.

Correct Answer: B

Rationale: The most likely diagnosis for the given presentation is Gastro-oesophageal reflux disease (GERD). The chest pain exacerbated by lying flat and relieved by leaning forward is typical of GERD due to acid reflux when lying down. Angina and myocardial infarction typically present with exertional chest pain, while pulmonary embolism presents with sudden onset pleuritic chest pain often associated with shortness of breath. Therefore, the correct answer is B.