Final answer:
The parathyroid gland produces parathyroid hormone, which raises blood calcium levels by influencing the kidneys, bones, and digestive system.
Step-by-step explanation:
The gland that produces and releases a hormone that raises blood calcium levels is the parathyroid gland. This gland is located on the posterior of the thyroid gland and produces parathyroid hormone (PTH). PTH functions to increase blood calcium concentrations when calcium ion levels fall below normal. It does this by enhancing reabsorption of Ca²+ by the kidneys, stimulating osteoclast activity (which breaks down bone, releasing calcium), and stimulating the synthesis and secretion of calcitriol by the kidneys, which enhances Ca²+ absorption by the digestive system.