Calcitonin

Definition

Calcitonin is a hormone produced by the thyroid gland that plays a crucial role in the regulation of calcium and phosphate levels in the body. It acts to lower blood calcium levels by inhibiting the activity of osteoclasts, the cells responsible for breaking down bone tissue.

5 Must Know Facts For Your Next Test

1. Calcitonin is secreted by the parafollicular cells, also known as C-cells, located in the thyroid gland.
2. The primary function of calcitonin is to lower blood calcium levels by inhibiting the activity of osteoclasts, which break down bone tissue.
3. Calcitonin promotes the deposition of calcium and phosphate into bone, thereby decreasing their concentrations in the blood.
4. Calcitonin also increases the excretion of calcium and phosphate through the kidneys, further lowering their levels in the blood.
5. Calcitonin plays a crucial role in maintaining calcium homeostasis, working in opposition to parathyroid hormone (PTH), which increases blood calcium levels.

Review Questions

• Explain the role of calcitonin in regulating calcium and phosphate levels in the body.
  • Calcitonin is a hormone produced by the thyroid gland that acts to lower blood calcium levels. It does this by inhibiting the activity of osteoclasts, the cells responsible for breaking down bone tissue and releasing calcium into the bloodstream. Calcitonin promotes the deposition of calcium and phosphate into bone, thereby decreasing their concentrations in the blood. It also increases the excretion of calcium and phosphate through the kidneys, further lowering their levels in the blood. In this way, calcitonin plays a crucial role in maintaining calcium homeostasis, working in opposition to parathyroid hormone (PTH), which increases blood calcium levels.
• Describe the relationship between calcitonin and the parathyroid hormone (PTH) in regulating calcium and phosphate levels.
  • Calcitonin and parathyroid hormone (PTH) work in opposition to each other in regulating calcium and phosphate levels in the body. Calcitonin acts to lower blood calcium levels by inhibiting the activity of osteoclasts, the cells responsible for breaking down bone tissue and releasing calcium into the bloodstream. In contrast, PTH increases blood calcium levels by stimulating the activity of osteoclasts and promoting the release of calcium from bone. This counterbalance between calcitonin and PTH is crucial for maintaining calcium homeostasis, ensuring that calcium and phosphate levels are kept within a narrow, optimal range for proper physiological functioning.
• Analyze the potential clinical implications of dysregulation of calcitonin secretion or function.
  • Dysregulation of calcitonin secretion or function can have significant clinical implications. Decreased calcitonin production or impaired calcitonin function can lead to elevated blood calcium levels, a condition known as hypercalcemia. This can result in symptoms such as nausea, vomiting, constipation, and kidney stones, and may also contribute to the development of osteoporosis due to increased bone resorption. Conversely, excessive calcitonin production or hypersensitivity to calcitonin can lead to low blood calcium levels, or hypocalcemia, which can cause muscle cramps, seizures, and cardiac arrhythmias. Understanding the role of calcitonin in calcium homeostasis is crucial for the diagnosis and management of various calcium-related disorders, such as thyroid gland dysfunction, parathyroid disorders, and certain types of cancer.

Related terms

Osteoclasts: Cells responsible for breaking down bone tissue and releasing calcium into the bloodstream.

Parathyroid Hormone (PTH): A hormone produced by the parathyroid glands that works in opposition to calcitonin to increase blood calcium levels.

Calcium Homeostasis: The process of maintaining a stable concentration of calcium in the blood and other bodily fluids.