Vitamin D | Biosynthesis & the Vitamin D Receptor

The video explains the biosynthetic pathway of vitamin D, highlighting its sources, including dietary intake and de novo synthesis. It details the role of 7-dehydrocholesterol in cholesterol and vitamin D synthesis, emphasizing the non-enzymatic reactions driven by sunlight. The conversion of cholecalciferol to active vitamin D (calcitriol) is discussed, along with its physiological effects, such as promoting insulin sensitivity and reducing inflammation. The mechanism of the vitamin D receptor is explored, and the impact of statins on vitamin D synthesis is addressed.

What are the two primary sources of vitamin D for humans?

• Exercise and medication

• Biosynthesis and medication

• Dietary intake and exercise

• Dietary intake and biosynthesis

What is the role of sunlight in the conversion of 7-dehydrocholesterol?

• It provides heat for the conversion

• It acts as a catalyst for the reaction

• It supplies UV light for the conversion

• It provides enzymes for the reaction

Which enzyme in the liver converts cholecalciferol to calcidiol?

• HMG-CoA reductase

• 1-hydroxylase

• 7-dehydrocholesterol reductase

• 25-hydroxylase

What is the active form of vitamin D known as?

• 7-dehydrocholesterol

• Calcitriol

• Cholecalciferol

• Calcidiol

How does calcitriol affect insulin sensitivity?

• It increases insulin sensitivity

• It has no effect on insulin sensitivity

• It causes insulin resistance

• It decreases insulin sensitivity

What is one of the anti-inflammatory roles of vitamin D?

• It modulates the immune response

• It increases inflammation

• It decreases lipid levels

• It increases blood sugar levels

Which of the following is a consequence of vitamin D deficiency?

• Increased insulin resistance

• Balanced serum lipids

• Decreased inflammation

• Increased insulin sensitivity

What is the role of the vitamin D receptor in the cell?

• It is located on the plasma membrane

• It degrades vitamin D in the nucleus

• It is responsible for vitamin D synthesis

• It binds to vitamin D in the cytoplasm

What happens to vitamin D synthesis when taking statin medications?

• It remains unchanged

• It becomes more efficient

• It increases significantly

• It decreases significantly

Why might individuals on statin medications need to increase dietary vitamin D?

• Statins inhibit de novo vitamin D synthesis

• Statins enhance vitamin D absorption

• Statins decrease cholesterol levels

• Statins increase vitamin D synthesis