What is the most common cause of peptic ulcer disease?

Correct Answer: C

Rationale: The correct answer is C: Helicobacter pylori infection. This bacterium is the most common cause of peptic ulcer disease by causing inflammation and weakening the protective lining of the stomach or duodenum. Studies have shown a strong association between H. pylori infection and peptic ulcers. A high-fat diet (A) may exacerbate symptoms but is not the primary cause. Stress (B) and alcohol consumption (D) can worsen symptoms but do not directly cause peptic ulcers. In summary, H. pylori infection is the leading cause of peptic ulcer disease due to its ability to damage the stomach lining.

Correct Answer: C

Rationale: The correct answer is C: larger blood vessels. The submucosa is a layer of connective tissue deep to the mucosa, which contains larger blood vessels that supply nutrients to the mucosa and surrounding tissues. This is essential for the maintenance of tissue health and function. The other choices are incorrect because: A: The presence of white blood cells does not differentiate the submucosa from the lamina propria. B: Both the submucosa and lamina propria contain lymphatic tissue, so the amount of lymphatic tissue does not differentiate them. D: Collagen fibers are present in both the submucosa and lamina propria, so the thickness of collagen fibers is not a distinguishing factor.

Correct Answer: B

Rationale: The correct answer is B: a serous membrane, or serosa. The mesentery and lining of the peritoneal cavity are composed of a serous membrane, which is a type of epithelial membrane that secretes a fluid to reduce friction between organs. The outermost layer of the digestive tract is also made up of a serous membrane, known as the serosa. This similarity in composition helps in the smooth movement of organs within the abdominal cavity. Choices A, C, and D are incorrect because the mesentery and peritoneal cavity do not consist of a mucous membrane (mucosa), submucous membrane (submucosa), or endothelial membrane (endothelium).

Correct Answer: A

Rationale: The correct answer is A: keratinized epithelial tissue. Filiform papillae are composed of keratinized epithelial cells that form the whitish tips on the surface of the tongue. These cells are designed to provide a rough surface to help with food manipulation. Collagen (B) is a structural protein found in connective tissue, not in filiform papillae. Mucous (C) is a secretion produced by mucous glands and is not a component of filiform papillae. Taste buds (D) are specialized structures responsible for detecting taste, located in fungiform and circumvallate papillae, not in filiform papillae.

Correct Answer: D

Rationale: The correct answer is D: lacteals. Lacteals are lymphatic vessels found within intestinal villi that absorb dietary lipids and transport them to the circulatory system. They play a crucial role in the absorption of fats. Capillaries (A) are small blood vessels, ductules (B) are small ducts, and canaliculi (C) are small channels within tissues. These structures do not specifically transport lipids from the intestines to the circulatory system like lacteals do.