Which statement about the urinary system is NOT correct?

Which statement about the urinary system is NOT correct?

• A. The left kidney is usually lower than the right
• B. The kidneys are retroperitoneal organs
• C. The kidneys filter blood to form urine
• D. Each kidney contains about one million nephrons

Answer: (A)

The statement is not correct because the left kidney is usually higher than the right, not lower. The liver on the right side pushes the right kidney slightly downward, so the right kidney sits lower and the left kidney sits higher. The kidneys are retroperitoneal organs, meaning they lie behind the peritoneal lining of the abdominal cavity. They are positioned against the posterior abdominal wall and are protected by fat and fascia. Functionally, the kidneys filter blood to form urine through the nephron units, performing glomerular filtration followed by tubular reabsorption and secretion to produce urine. Each kidney contains about one million nephrons, give or take, which provides the massive filtering capacity needed to maintain fluid and electrolyte balance.

The statement is not correct because the left kidney is usually higher than the right, not lower. The liver on the right side pushes the right kidney slightly downward, so the right kidney sits lower and the left kidney sits higher.

The kidneys are retroperitoneal organs, meaning they lie behind the peritoneal lining of the abdominal cavity. They are positioned against the posterior abdominal wall and are protected by fat and fascia.

Functionally, the kidneys filter blood to form urine through the nephron units, performing glomerular filtration followed by tubular reabsorption and secretion to produce urine.

Each kidney contains about one million nephrons, give or take, which provides the massive filtering capacity needed to maintain fluid and electrolyte balance.