Which two elements are involved in the principle of negative feedback in the body?

The principle of negative feedback is a critical component of homeostasis in the body, helping to maintain equilibrium by regulating physiological processes. In this context, phosphorus and calcium are essential elements that play key roles in various bodily functions, particularly in the processes of hormone regulation and bone health.

Calcium is vital for muscle contraction, nerve transmission, and blood clotting, while phosphorus is crucial for energy production (notably ATP synthesis), cell membrane formation, and bone mineralization. The relationship between these two elements is particularly important in managing calcium levels in the blood. The parathyroid hormone (PTH) and calcitonin are two major hormones that regulate calcium levels through negative feedback mechanisms. When calcium levels rise, calcitonin is released to lower them; conversely, when levels fall, PTH is secreted to increase calcium levels. This interplay exemplifies how negative feedback maintains stable internal conditions.

While the other options may involve elements necessary for various bodily functions, they do not directly pertain to the critical feedback mechanisms that regulate homeostasis in the context of calcium and phosphorus. Thus, phosphorus and calcium are the correct elements involved in the principle of negative feedback.