The component parts of the myenteric plexus of the enteric nervous system includes the following except:

Correct Answer: B

Rationale: The correct answer is B: Control centers in the medulla oblongata. The myenteric plexus is part of the enteric nervous system located in the gastrointestinal tract, involved in regulating gut motility. Sensory neurons (A), motor neurons (C), and synapses (D) are essential components of the myenteric plexus, responsible for sensing stimuli, transmitting signals, and coordinating muscle contractions in the gut. Control centers in the medulla oblongata are part of the central nervous system, not directly related to the myenteric plexus functions. Thus, choice B is incorrect in the context of the components of the myenteric plexus.

Correct Answer: C

Rationale: The correct answer is C: Meckel's diverticulum. Meckel's diverticulum is a congenital outpouching of the small intestine that may contain gastric or pancreatic tissue, leading to ulceration and bleeding. In this case, the presence of blood in the stools along with abdominal tenderness and anemia is highly suggestive of Meckel's diverticulum. Pyloric stenosis typically presents with non-bloody projectile vomiting in a male infant. Intestinal atresia usually presents with bilious vomiting and abdominal distension in a newborn. Hirschsprung's disease presents with chronic constipation and failure to pass meconium shortly after birth. Therefore, based on the symptoms and age of the child, Meckel's diverticulum is the most likely diagnosis.

Correct Answer: B

Rationale: The correct answer is B: stomach. This morphologic pattern is most commonly seen in scirrhous (fibrous) type of gastric carcinoma. The diffuse intramural spread with extensive fibroblastic thickening is a characteristic feature of scirrhous gastric cancer. This pattern is not typically associated with carcinoma of the esophagus, small intestine, or appendix. The fibroblastic thickening in the stomach is due to desmoplastic reaction caused by the tumor cells, leading to the characteristic linitis plastica appearance on imaging.

Correct Answer: B

Rationale: The correct answer is B: Helps in food absorption. Chewing primarily aids in food breakdown into smaller particles for easier digestion. Chewing does not directly contribute to food absorption, as absorption mainly occurs in the small intestine. A: Sense of satiety is correct, as chewing helps signal fullness to the brain. C: Helps in food digestion is correct, as chewing starts the mechanical breakdown process. D: Increase salivary secretion is incorrect, as chewing stimulates saliva production to aid in digestion.

Correct Answer: A

Rationale: Rationale for Correct Answer A: - Parietal cells in gastric glands secrete gastric acid in response to hormonal stimulation, primarily gastrin. - Gastrin is released in response to the presence of food in the stomach, stimulating acid secretion. - This process is essential for digestion and maintaining the acidity of the stomach environment. Summary of Incorrect Choices: - B: Most of the secretion of acid and pepsinogen occurs during the gastric (not intestinal) phase. - D: Gastric secretion begins before food enters the stomach, as cephalic phase responses can initiate acid secretion.