What are the primary functions of the kidneys?

• A. Producing insulin and regulating metabolism
• B. Filtering blood, regulating fluid balance, and maintaining homeostasis
• C. Digesting food and absorbing nutrients
• D. Producing bile and storing fat

Answer: (B)

The primary functions of the kidneys include filtering blood, regulating fluid balance, and maintaining homeostasis. The kidneys are vital organs that play a crucial role in excretion, where they filter waste products and excess substances from the blood, forming urine to remove them from the body.

They are also essential for regulating the body's fluid balance by controlling the volume and concentration of urine produced in response to hydration status, thus ensuring that electrolyte levels remain stable. This fluid regulation contributes to maintaining homeostasis, which refers to the stable internal conditions needed for optimal cellular function.

Additionally, the kidneys are involved in the regulation of various ions and metabolites, water balance, acid-base balance, and blood pressure through the renin-angiotensin-aldosterone system. Together, these processes ensure that the body remains in a balanced state despite changes in diet, environment, and physical activity. The selection of this answer reflects the comprehensive role of the kidneys in overall health and metabolic function.