What is the main role of the excretory system?

• A. To procure nutrients
• B. To filter waste from the blood
• C. To regulate temperature
• D. To circulate blood

Answer: (B)

The main role of the excretory system is to filter waste from the blood. This system, which includes organs such as the kidneys, ureters, bladder, and urethra, plays a crucial part in maintaining homeostasis by removing waste products that can be harmful if they accumulate in the body.

As blood circulates through the kidneys, they filter out toxins, excess salts, and urea, a waste product from the metabolism of proteins. This filtered waste is then excreted as urine. Through this process, the excretory system helps regulate the body's fluid balance and electrolyte levels, ensuring that essential substances are retained while waste is effectively eliminated.

In contrast, the other options serve different functions. The role of procuring nutrients is associated with the digestive system, which breaks down food and absorbs essential nutrients. Regulating temperature is primarily the function of the integumentary and nervous systems, which control body temperature through mechanisms such as sweating and blood flow adjustments. Circulating blood is the primary function of the cardiovascular system, which transports nutrients, gases, and waste products throughout the body. Each system plays a distinct role, but the excretory system is specifically designed for waste filtration and elimination.