Absence of ganglion cells is an essential diagnostic feature of:

Correct Answer: B

Rationale: The correct answer is B: Hirschsprung's disease. The absence of ganglion cells in the distal colon is a key diagnostic feature of Hirschsprung's disease. Ganglion cells are essential for coordinated contractions of the colon. In congenital pyloric stenosis, the issue lies in the pylorus, not the colon, so ganglion cells are not relevant. Choice C is incorrect because congenital pyloric stenosis does not involve ganglion cells. Choice D is also incorrect as Hirschsprung's disease does indeed involve the absence of ganglion cells.

Correct Answer: B

Rationale: The correct answer is B because the buccal phase of swallowing is a voluntary process where the tongue moves the bolus of food towards the back of the mouth to initiate swallowing. This phase is under conscious control and initiates the swallowing reflex. Choice A is incorrect because the buccal phase is voluntary, not involuntary. Choice C is incorrect because the bolus is moved towards the back of the mouth, not rolled over the front of the tongue. Choice D is incorrect because the movement of food from the pharynx to the esophagus occurs during the pharyngeal phase of swallowing, not the buccal phase.

Correct Answer: D

Rationale: The correct answer is D: Submucosa. The submucosa is the layer of tissue beneath the mucosa in the gastrointestinal tract. It contains blood vessels, nerves, and glands that support the mucosa. Muscularis externa (A) is the layer of smooth muscle responsible for peristalsis. Circular muscle (B) is a type of muscle fiber found within the muscularis externa. Serosa (C) is the outermost layer of the digestive tract that provides protection and secretes fluid. The submucosa (D) is the correct answer because it is the layer directly beneath the mucosa and plays a crucial role in supporting and nourishing the mucosal layer.

Correct Answer: B

Rationale: The correct answer is B: To increase surface area for absorption. Villi and microvilli are tiny finger-like projections in the small intestine that greatly increase the surface area for nutrient absorption. This increased surface area allows for more efficient absorption of nutrients into the bloodstream. Choice A is incorrect because villi and microvilli do not secrete digestive enzymes; rather, they facilitate absorption of nutrients already broken down by enzymes. Choice C is incorrect as villi and microvilli do not transport nutrients to the liver; they absorb nutrients into the bloodstream for circulation to various body tissues. Choice D is incorrect because villi and microvilli do not store excess nutrients; their primary function is absorption.

Correct Answer: A

Rationale: The correct answer is A: Obtain a venous blood glucose specimen. This is the appropriate action because capillary blood glucose levels can be inaccurate during PN infusions due to the high glucose content of the PN solution. Venous blood glucose levels provide a more accurate assessment of the patient's glycemic status. Slowing the infusion rate (Choice B) may not address the underlying issue of inaccurate readings. Rechecking capillary blood glucose levels (Choice C) will likely yield the same inaccurate results. Contacting the healthcare provider for infusion rate changes (Choice D) may be necessary but should be based on accurate glucose levels.