Which of the following is the most common permanent disability in childhood?

Correct Answer: C

Rationale: Cerebral palsy is the most common permanent disability in childhood among the options provided. It is a group of disorders that affect movement and muscle coordination due to damage or abnormal development in the brain. Cerebral palsy can occur before, during, or shortly after birth, and it is a lifelong condition that impacts a child's ability to move, maintain balance, and posture. Scoliosis, muscular dystrophy, and developmental dysplasia of the hip (DDH) are also significant conditions that can lead to disabilities in children, but they are not as prevalent as cerebral palsy in terms of permanent disabilities in childhood.

Correct Answer: B

Rationale: The ductus arteriosus is a fetal blood vessel that connects the pulmonary artery to the aorta. Its main function is to bypass the non-functional fetal lungs by shunting blood from the pulmonary artery (which carries deoxygenated blood) directly to the systemic circulation, specifically the aorta. This allows oxygenated blood from the placenta to be distributed to the body's organs and tissues without having to first pass through the lungs for oxygen exchange. After birth, when the baby begins to breathe and oxygenate its blood through the lungs, the ductus arteriosus normally closes within the first few days to weeks of life.

Correct Answer: C

Rationale: Cystic fibrosis (CF) is caused by mutations in the CFTR gene, leading to altered transport of sodium and chloride ions in and out of epithelial cells. This results in the production of secretions that are low in sodium chloride, leading to thickened mucus. The abnormally thick, abundant secretions from mucous glands in the respiratory tract can obstruct the airways, leading to chronic, diffuse obstructive pulmonary disease in almost all patients with CF. This process impairs mucociliary clearance, predisposing individuals to recurrent lung infections, inflammation, and ultimately bronchiectasis. This mechanism is a key factor in the pathophysiology of cystic fibrosis-associated obstructive lung disease.

Correct Answer: A

Rationale: Adequate cardiac output is a measure of how well the heart is able to pump blood effectively to meet the body's metabolic demands. An adequate cardiac output ensures sufficient oxygen and nutrients are delivered to the tissues and organs. One of the most reliable indicators of adequate cardiac output is urine output. A urine output of at least 1 mL/kg/hour, which translates to around 30 mL/hour in a 5-year-old child, indicates adequate perfusion and renal function. In heart failure, decreased cardiac output may lead to decreased renal perfusion, resulting in a decreased urine output, so a stable or increased urine output suggests adequate cardiac output.

Correct Answer: A

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.