What role do the kidneys play in homeostasis?

• A. Regulating fluid balance, electrolyte levels, and waste removal
• B. Generating red blood cells and regulating blood flow
• C. Secreting hormones and maintaining blood pressure
• D. Facilitating gas exchange and oxygen transport

Answer: (A)

The kidneys are essential organs in maintaining homeostasis within the body primarily by regulating fluid balance, electrolyte levels, and waste removal. They achieve this through a complex system of filtration, reabsorption, and secretion.

Firstly, the kidneys filter blood, removing waste products and excess substances, which helps to maintain a stable internal environment. By adjusting the amount of water and electrolytes—such as sodium, potassium, and calcium—they can control blood volume and pressure, thereby contributing to fluid balance. This regulation is crucial, as it affects how cells function and ensures that the body operates within its optimal ranges.

Additionally, through the process of urine formation, the kidneys eliminate metabolites and toxins that can accumulate and disrupt various body systems. This waste removal is vital for maintaining homeostasis, as it prevents harmful substances from reaching toxic levels in the bloodstream.

While the other choices mention important functions related to organ systems, they do not encapsulate the primary roles played by the kidneys in maintaining homeostasis as effectively as the correct choice. For example, generating red blood cells and regulating blood flow relates more to bone marrow and the cardiovascular system, respectively, while secreting hormones is a role of the endocrine system and gas exchange is primarily handled by the respiratory system. Therefore, the comprehensive