Which one of the following cells in the gastric glands produce pepsinogen?

Correct Answer: C

Rationale: The correct answer is C: chief or zymogenic cells. These cells are responsible for producing pepsinogen, the inactive form of pepsin, which is an enzyme that helps in protein digestion. Chief cells secrete pepsinogen into the gastric lumen. Endocrine cells (A) produce hormones like gastrin, mucous neck cells (B) secrete mucus to protect the stomach lining, and parietal cells (D) secrete hydrochloric acid to create an acidic environment for pepsinogen activation. Therefore, the correct choice is C as it directly produces pepsinogen.

Correct Answer: A

Rationale: The correct answer is A: intercalated duct. The aqueous component of pancreatic juice is produced by intercalated ducts, which are responsible for secreting bicarbonate-rich fluid to neutralize the acidic chyme entering the duodenum. Other choices are incorrect because pancreatic islets (B) secrete hormones like insulin and glucagon, acinar cells (C) secrete digestive enzymes, and the duodenum (D) is the first part of the small intestine where pancreatic juice is delivered but not where it is produced.

Correct Answer: C

Rationale: The correct answer is C: low-density lipoproteins (LDL). LDL carries cholesterol to tissues where it is needed for steroid synthesis and bile salt production. LDL is known as the "bad" cholesterol transporter because high levels can lead to plaque buildup in arteries. Micelles (A) are small lipid droplets in the intestine, chylomicrons (B) transport dietary fats, and HDL (D) is known as the "good" cholesterol transporter that helps remove excess cholesterol from the bloodstream.

Correct Answer: D

Rationale: The correct answer is D because flavor signals from tasty, processed food can indeed override satiety signals even after a large meal. This is due to the hedonic aspect of eating, where the pleasure derived from consuming flavorful foods can lead to overeating despite feeling full. The brain's reward system plays a significant role in this process, causing individuals to continue eating beyond their caloric needs. In contrast, choices A, B, and C do not accurately describe the role of the intestine in the development of obesity. Choice A focuses on hormonal imbalances, which can contribute to obesity but does not solely explain the complex nature of obesity development. Choice B oversimplifies the control of energy intake, disregarding the various factors influencing eating behaviors. Choice C places the blame solely on personal choices without considering the physiological and psychological factors that contribute to overeating.

Correct Answer: B

Rationale: Answer B is correct because the major histocompatibility complex (MHC) is indeed required for the activation of T helper cells by a foreign antigen. This is because T helper cells recognize antigens presented by MHC molecules on antigen-presenting cells. Without MHC presentation, T helper cells cannot be activated. Choice A is incorrect because MHC molecules do display both self and non-self antigens, which is crucial for the immune system to distinguish between harmful invaders and healthy cells. Choice C is incorrect because activated effector T helper cells can indeed activate both T and B lymphocytes/cells, playing a key role in coordinating the adaptive immune response. Choice D is incorrect because T cells do not use 'chemical warfare'; instead, they directly attack infected cells, while B cells produce antibodies that target specific antigens. In summary, choice B is false because the MHC is necessary for T helper cell activation, while choices A, C, and D are true statements regarding the adaptive immune response.