Cholecalciferol

Definition

Cholecalciferol, also known as vitamin D3, is a fat-soluble vitamin that plays a crucial role in the regulation of calcium and phosphate homeostasis, as well as in the maintenance of the musculoskeletal and integumentary systems.

5 Must Know Facts For Your Next Test

1. Cholecalciferol is synthesized in the skin through the action of ultraviolet B (UVB) radiation on the precursor molecule 7-dehydrocholesterol.
2. Cholecalciferol is then transported to the liver, where it is converted to 25-hydroxycholecalciferol, the main circulating form of vitamin D.
3. In the kidneys, 25-hydroxycholecalciferol is further converted to calcitriol, the active form of vitamin D, which regulates calcium and phosphate homeostasis.
4. Vitamin D, including cholecalciferol, plays a crucial role in the maintenance of bone health by promoting the absorption of calcium and phosphate from the intestine.
5. Adequate levels of cholecalciferol are also important for the proper functioning of the musculoskeletal and integumentary (skin) systems.

Review Questions

• Explain the process of cholecalciferol synthesis and activation in the body.
  • Cholecalciferol, or vitamin D3, is synthesized in the skin through the action of ultraviolet B (UVB) radiation on the precursor molecule 7-dehydrocholesterol. The synthesized cholecalciferol is then transported to the liver, where it is converted to 25-hydroxycholecalciferol, the main circulating form of vitamin D. In the kidneys, 25-hydroxycholecalciferol is further converted to calcitriol, the active form of vitamin D, which regulates calcium and phosphate homeostasis in the body.
• Describe the role of cholecalciferol in the maintenance of the musculoskeletal and integumentary systems.
  • Adequate levels of cholecalciferol, or vitamin D3, are essential for the proper functioning of the musculoskeletal and integumentary (skin) systems. Vitamin D promotes the absorption of calcium and phosphate from the intestine, which are crucial for the development and maintenance of strong bones. Additionally, vitamin D has been shown to play a role in muscle function and the regulation of skin health, as it is involved in cellular differentiation and proliferation processes.
• Analyze the relationship between cholecalciferol, parathyroid hormone (PTH), and calcium/phosphate homeostasis.
  • Cholecalciferol, or vitamin D3, works in conjunction with parathyroid hormone (PTH) to regulate calcium and phosphate homeostasis in the body. Calcitriol, the active form of vitamin D, increases the absorption of calcium and phosphate from the intestine and promotes their mobilization from the bones. PTH, on the other hand, stimulates the conversion of 25-hydroxycholecalciferol to calcitriol in the kidneys, as well as the release of calcium from the bones. The interplay between cholecalciferol, PTH, and the regulation of calcium and phosphate levels is crucial for maintaining the health of the musculoskeletal and integumentary systems.

Related terms

Ergocalciferol: Ergocalciferol, or vitamin D2, is another form of vitamin D that can be obtained from plant sources, but it is less potent than cholecalciferol.

Calcitriol:

Calcitriol is the active form of vitamin D, which is produced in the kidneys and is responsible for the biological effects of vitamin D in the body.

Parathyroid Hormone (PTH): Parathyroid hormone is a hormone produced by the parathyroid glands that regulates calcium and phosphate homeostasis, working in conjunction with vitamin D.