Why is most food digested?

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. This allows for efficient nutrient uptake in the body. Choice A is incorrect because digestive enzymes can still function with a specific substrate. Choice B is incorrect as digestion is not primarily for balancing the diet. Choice D is incorrect as the main purpose of digestion is not to prevent disorders of the intestine but to break down food for absorption.

Correct Answer: A

Rationale: The correct answer is A: esophagus. The esophagus is a muscular tube that connects the mouth to the stomach, allowing food to pass through for digestion. It does not have a role in breathing (like the trachea), nor is it part of the upper respiratory tract (nasopharynx). The epiglottis is a flap that covers the trachea during swallowing to prevent food from entering the airway, but it doesn't transport food to the stomach. Therefore, the esophagus is the correct answer as it specifically functions to pass food from the mouth to the stomach.

Correct Answer: B

Rationale: The correct answer is B: Gastro-oesophageal reflux disease. This is known as the classic presentation of pericarditis. The pain worsens when lying flat due to increased pressure on the inflamed pericardium, and improves when leaning forward, reducing pressure. Angina (A) typically presents with exertional chest pain, not worsened by lying flat. Myocardial infarction (C) presents with crushing chest pain, not positional like pericarditis. Pulmonary embolism (D) presents with sudden onset dyspnea and chest pain, not exacerbated by lying flat.

Correct Answer: D

Rationale: The most likely diagnosis for the 50-year-old man with swollen ankles, raised jugular venous pressure, and a history of chronic obstructive pulmonary disease is right heart failure (Choice D). In this case, the patient's symptoms suggest signs of right-sided heart failure, such as peripheral edema and jugular venous distention. Chronic obstructive pulmonary disease can lead to pulmonary hypertension, causing right heart failure. Asthma (Choice A) is primarily a respiratory condition, not typically associated with jugular venous distention or peripheral edema. Congestive heart failure (Choice B) usually presents with features of pulmonary edema and bilateral lower extremity edema, rather than isolated right-sided heart failure. Constrictive pericarditis (Choice C) may present with jugular venous distention, but it is less common compared to right heart failure in a patient with a history of chronic obstructive pulmonary disease.

Correct Answer: A

Rationale: The correct answer is A because cor pulmonale refers to right-sided heart failure caused by lung disease. In chronic obstructive pulmonary disease (COPD), the lungs are diseased, leading to pulmonary hypertension and subsequent strain on the right side of the heart. This results in right ventricular hypertrophy and eventually right-sided heart failure. Choice B is incorrect because left-sided heart failure is not the primary cause of cor pulmonale in COPD. Choice C is incorrect as it suggests that lung disease is secondary to left-sided heart failure, which is not the case in cor pulmonale. Choice D is also incorrect as it implies that lung disease leads to right-sided heart failure, which is the opposite of the actual relationship in cor pulmonale.