The submucosa differs from lamina propria by having:

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: 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.

Correct Answer: B

Rationale: The correct answer is B: stratified squamous. The esophagus and anal canal are exposed to mechanical stress and abrasion, requiring a protective epithelium. Stratified squamous epithelium is ideal for this role due to its multiple layers of cells that provide durability and protection against wear and tear. Simple squamous epithelium (choice A) is too thin and fragile for this function. Simple columnar epithelium (choice C) is specialized for secretion and absorption, not for protection. Stratified columnar epithelium (choice D) is relatively rare in the body and not typically found in areas requiring high protection like the esophagus and anal canal.

Correct Answer: C

Rationale: The correct answer is C: small intestine. The small intestine is characterized by permanent folds called plicae circulares, which increase the surface area for nutrient absorption. These folds help to slow down the passage of food and increase contact with the intestinal walls. The other choices are incorrect because the esophagus (A) does not have permanent folds, the stomach (B) has rugae (temporary folds), and the large intestine (D) has haustra (pouches), not permanent folds like the small intestine.