Question

Which of the following is a functions of the kidney?

• A. Filtration of blood to remove wastes.
• B. Blood pressure regulation
• C. pH regulation
• D. Both A and C
  
• E. All of the above

Answer 1

The correct option is E All of the above

Waste excretion: The kidneys filter out toxins, excess salts, and urea, a nitrogen-based waste created by cell metabolism. Urea is synthesized in the liver and transported through the blood to the kidneys for removal.

Water level balancing: As the kidneys are key in the chemical breakdown of urine, they react to changes in the body’s water level throughout the day. As water intake decreases, the kidneys adjust accordingly and leave water in the body instead of helping excrete it.

Blood pressure regulation: The kidneys need constant pressure to filter the blood. When it drops too low, the kidneys increase the pressure. One way is by producing a blood vessel-constricting protein (angiotensin) that also signals the body to retain sodium and water. Both the constriction and retention help restore normal blood pressure.

Red blood cell regulation: When the kidneys don’t get enough oxygen, they send out a distress call in the form of erythropoietin, a hormone that stimulates the bone marrow to produce more oxygen-carrying red blood cells.

Acid regulation: As cells metabolize, they produce acids. The excess of acid is neutralized by the kidney.

So, the correct answer is option E.