Final answer:
The parathyroid glands are located on the posterior surface of the thyroid gland and produce parathyroid hormone (PTH) to regulate blood calcium concentrations. PTH enhances calcium reabsorption, stimulates osteoclast activity, and inhibits osteoblast activity. It also stimulates the synthesis and secretion of calcitriol, which enhances calcium absorption by the digestive system.
Step-by-step explanation:
The parathyroid glands are located on the posterior surface of the thyroid gland. They produce parathyroid hormone (PTH), which increases blood calcium concentrations when calcium ion levels fall below normal. PTH works by enhancing reabsorption of calcium by the kidneys, stimulating osteoclast activity, and inhibiting osteoblast activity. It also stimulates the synthesis and secretion of calcitriol by the kidneys, which enhances calcium absorption by the digestive system.
The parathyroid glands function in opposition to the thyroid gland, which releases calcitonin to decrease blood calcium levels when they become too high. PTH and calcitonin work together to maintain homeostatic calcium levels in the body fluids.
Overall, the parathyroid glands play a crucial role in the hormonal control of calcium homeostasis, ensuring that blood calcium levels are maintained within a normal range.