HESI Pediatrics Quizlet

Correct Answer: B

Rationale: The correct answer is B. Myelination occurs in a cephalocaudal (head-to-toe) pattern, improving nerve function progressively. Choice A is incorrect because myelination continues beyond 4 years of age and into adolescence. Choice C is incorrect as myelination speeds up nerve impulses rather than slowing them down. Choice D is incorrect because myelination increases the specificity and efficiency of nerve impulses, making them more focused and precise.

Correct Answer: B

Rationale: Rectal biopsy is the definitive diagnostic procedure for Hirschsprung disease in infants. This procedure reveals the absence of ganglion cells in the affected bowel segment, which is a hallmark of Hirschsprung disease. Colonoscopy (Choice A) is not typically used for diagnosing Hirschsprung disease due to the risk of not accurately reaching the affected segment. Multiple saline enemas (Choice C) are not used to confirm the diagnosis of Hirschsprung disease. Fiberoptic nasoenteric tube (Choice D) is not a standard diagnostic procedure for Hirschsprung disease and does not provide the necessary information to confirm the absence of ganglion cells in the affected bowel segment.

Correct Answer: D

Rationale: Mouth breathing due to a cleft lip can dry the mucous membranes, increasing their susceptibility to infection. While waste product accumulation (Choice A) and inadequate circulation (Choice B) may contribute to complications, they are not directly related to infection in this context. Inadequate nutrition (Choice C) may affect overall health but is not the primary reason for infection predisposition in this case.

Correct Answer: A

Rationale: The correct answer is A: 'It is a condition affecting the respiratory and digestive systems.' Cystic fibrosis is a genetic disorder that primarily affects the respiratory and digestive systems. It is caused by a defective gene that leads to the production of thick and sticky mucus in these organs. This mucus can clog airways in the lungs and block the ducts in the pancreas, affecting digestion. Choice B is incorrect because cystic fibrosis is not an autoimmune disorder; it is a genetic condition. Choice C is partially correct in that cystic fibrosis is a genetic disorder, but merely managing it with medication oversimplifies the comprehensive care needed for individuals with cystic fibrosis. Choice D is incorrect as cystic fibrosis is not caused by prenatal exposure to toxins but is a genetic condition inherited from parents.

Correct Answer: C

Rationale: Positive fibrin split products are indicative of disseminated intravascular coagulation (DIC). In DIC, there is widespread clotting and subsequent consumption of clotting factors, leading to the formation of fibrin split products. A shortened prothrombin time (Choice A) is not typically seen in DIC as it indicates faster clotting, which is opposite to the pathophysiology of DIC. An increased fibrinogen level (Choice B) may be observed in the early stages of DIC due to the compensatory increase in production, but it is not a definitive indicator. Increased platelets (Choice D) may be seen in the early stages of DIC due to the body's attempt to compensate for clot formation, but it is not a specific finding for DIC.