Vit D
What is osteomalacia?
The softening of the bones; impaired mineralization of the bone matrix
How do humans obtain Vitamin D?
Through dietary intake and sunlight exposure.
How is Vitamin D transported in the blood?
Vit D is transported in the blood via Vitamin D binding protein (DBP) and delivered to the liver for storage or to the kidney of activation.
What are the molecular characteristics of Vit D?
Vitamin D is secosteroid and fat-soluble prohormone
What occurs when someone is deficient in Vitamin D?
You have impaired absorption of calcium and phosphorus you have impaired differentiation of enterocytes and a deficiency is known to be associated with MS, inflammatory bowel disease, and cancers.
What is a prophormone?
an inactive precursor of a hormone.
why are obese individuals at high risk for vit d deficiency?
because increased subcutaneous fat results in increased storage of vit D and less for bioavailability
Why are dark-skinned individuals at high risk for vit d deficiency?
because melanin competes with vit D precursors in the skin for absorption of UV light. UV light is needed to activate vit D precursors for vit D generation
Why are individuals with kidney disease at high risk for vit d deficiency?
due to decreased hormonal regulation of active vit D from the kidney
why are the elderly at high risk for vitamin D deficiency?
due to decreased levels of vitamin D precursors in the skin
What is Vitamin D2
ergocalciferol
What happens to Vitamin D once it is activated?
it is secreted into circulation for delivery to target organs, such as the intestines, bones, kidney and binds to vitamin D receptors within the plasma membrane of those cells.
What is Phosphopenic?
low levels of phosphate often a result of renal phosphoate wasting
What is secosteroid?
A steroid with a broken ring in its structure
Why are individuals with digestive disorders at high risk for Vit d deficiency?
Because the destruction of stomach and intestinal lining impairs fat absorption and vitamin D absorption from the diet
What is Vitamin D3
Cholecalciferol
What occurs with a vitamin D toxicity?
Hypercalcemia Hypercalciuria Nephrocalcinosis intraocular calcifications
In which organ is vitamin D activated?
In the kidney, it is hyroxylated.
How is Vit D3 obtained?
It is obtained from diet or synthesized from the skin via UV irradiation.
What are some causes for vit d deficiency?
Lack of sun exposure use of sunscreen extensive burns lack of dietary sources intestinal malabsorption of vit D Exclusive breast-fed infants - breast milk is low in vitamin A
What is Calcipenic/hypocalcemic?
Low levels of calcium; either as a result of lack of dietary calcium intake or vitamin D deficiency