In what way do the respiratory and urinary systems work together for acid-base balance?

• A. The respiratory system removes nutrients
• B. The urinary system regulates oxygen levels
• C. The respiratory system regulates carbon dioxide levels
• D. The urinary system eliminates carbon dioxide

Answer: (C)

The respiratory and urinary systems play crucial roles in maintaining acid-base balance within the body. The correct response points to the respiratory system's regulation of carbon dioxide levels.

When carbon dioxide is produced as a byproduct of metabolism, it combines with water in the bloodstream to form carbonic acid. This process means that an increase in carbon dioxide can lead to an increase in acidity (lower pH) of the blood. The respiratory system helps to regulate the amount of carbon dioxide in the body by controlling the rate and depth of breathing. When you breathe more rapidly or deeply, you expel more carbon dioxide, which can decrease acidity and counteract conditions like acidosis.

In contrast, the urinary system contributes to acid-base balance by regulating bicarbonate and hydrogen ion concentrations in the blood. However, it does not directly eliminate carbon dioxide, as its main role is in the excretion of nitrogenous wastes and regulation of water and electrolytes.

The other options each describe incorrect functions regarding the interplay between these systems in maintaining acid-base balance. For instance, nutrients are typically handled by the digestive system rather than the respiratory system, and oxygen regulation is primarily the responsibility of the respiratory system, not the urinary system.