Put simply, volume refers to the number of contracts traded. For any trade to occur, the market needs to produce a buyer and a seller. A transaction occurs when buyers and sellers meet and is referred to as the market price.
This hormone is secreted from cells of the parathyroid glands and finds its major target cells in bone and kidney. Another hormone, parathyroid hormone-related protein, binds to the same receptor as parathyroid hormone and has major effects on development.
Learn how parathyroid glands work by making parathyroid hormone to control blood and bone calcium. This page of Parathyroid.com discusses the normal function of parathyroid glands, how parathyroid glands monitor and control blood calcium and what it means to have high blood calcium.