If calcium levels are low, camp activity increases which leads to synthesis and release of parathyroid hormone. camp acts as a (n)

Second messenger

Explanation:

When a hormone binds on its cell receptor on the cell, it initiates a cascade of membrane protein changes that begin a secondary signaling process inside of the cell. The cAMP is a secondary messenger that is involved in intracellular signaling. In this case, it causes the cell to produce more PTH in response to low calcium levels.