Which of the following statements about the nephron is true?

The nephron is indeed considered the functional unit of the kidney, which underscores its essential role in various processes including filtration, reabsorption, secretion, and excretion. Each kidney contains approximately one million nephrons, which work collaboratively to maintain homeostasis by regulating fluid and electrolyte balance, as well as waste removal from the body.

In the nephron, blood is filtered in the glomerulus, while important substances such as water, ions, and nutrients are reabsorbed in the renal tubules. Additionally, the nephron plays a role in the secretion of certain substances, contributing to the regulation of blood pressure and electrolyte balance. This comprehensive functionality is why it is characterized as the functional unit of the kidney.