Vitamin A Quiz

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Questions and Answers

Which of the following statements about fat-soluble vitamins is true?

Fat-soluble vitamins are not transported with fats through the lymphatic system in chylomicrons before entering the blood.

Fat-soluble vitamins are easily excreted, reducing the risk of toxicity with high intakes.

Fat-soluble vitamins can be stored in body fat, meaning that intakes can vary without a risk of deficiency. (correct)

Fat-soluble vitamins do not require bile and dietary fat for absorption.

Which vitamin is synthesized by the host in amounts adequate to meet normal physiological needs?

Vitamin A

Vitamin K

Vitamin D (correct)

Vitamin E

What is the main route of absorption for fat-soluble vitamins?

Excreted through the kidneys into the urine

Through the lymphatic system in chylomicrons before entering the blood (correct)

Directly into the bloodstream from the digestive system

Absorbed by the liver before entering the bloodstream

What is the characteristic of fat-soluble vitamins that increases the risk of toxicity with high intakes?

Ability to be stored in body fat Signup and view all the answers

What is the main distinguishing factor of vitamins from fats, carbohydrates, and proteins?

Being essential for normal physiological function in very small amounts Signup and view all the answers

Which fat-soluble vitamin is known to be primarily obtained through exposure to sunlight?

Vitamin D Signup and view all the answers

What is the principle function of vitamin D?

To maintain levels of Ca and phosphorus in the blood for nerve transmission, muscle contraction, blood pressure regulation and release of hormones Signup and view all the answers

What is the active form of vitamin D?

1,25-dihydroxy vitamin D3 Signup and view all the answers

What happens when blood Ca levels drop?

Parathyroid gland releases parathyroid hormone (PTH) Signup and view all the answers

What is the consequence of vitamin D deficiency in children?

Rickets Signup and view all the answers

What is the role of active vitamin D at the intestine?

Increases the absorption of calcium from the diet Signup and view all the answers

What is the consequence of over-supplementation of vitamin D?

High blood and urine calcium concentrations Signup and view all the answers

What is the form of vitamin D synthesized in the skin?

7-dehydrocholesterol Signup and view all the answers

What is the first product formed in the liver from vitamin D?

25-hydroxy vitamin D3 Signup and view all the answers

Which form of vitamin A is crucial for light perception in the eye?

Retinal Signup and view all the answers

What are the two main categories of vitamin A compounds?

Retinoids and carotenoids Signup and view all the answers

How are retinoids and carotenoids transported to the liver from the intestine?

In chylomicrons Signup and view all the answers

What is the most common plant precursor of vitamin A?

Beta-carotene Signup and view all the answers

Which deficiency poses a threat to the health and sight of millions of children worldwide?

Vitamin A deficiency Signup and view all the answers

In which cycle does vitamin A combine with opsin to form rhodopsin?

Visual cycle Signup and view all the answers

Which vitamin is known to be primarily obtained through exposure to sunlight?

Vitamin D Signup and view all the answers

What is the characteristic of fat-soluble vitamins that increases the risk of toxicity with high intakes?

Can be stored in body fat Signup and view all the answers

What happens by the absence or underutilization of a specific vitamin?

Specific deficiency syndrome Signup and view all the answers

Which form of vitamin A plays a role in gene expression and regulates the production of proteins?

Retinoic acid Signup and view all the answers

What is the main cause of blindness in resource-poor countries?

Insufficient intake of vitamin A Signup and view all the answers

What is the primary function of vitamin A in the visual cycle?

Formation of rhodopsin Signup and view all the answers

What happens when blood calcium levels drop?

Parathyroid gland releases parathyroid hormone (PTH) which stimulates the kidney to activate enzymes to convert 25-hydroxyvitamin D3 to active form Signup and view all the answers

What is the consequence of over-supplementation of vitamin D?

High blood and urine calcium concentrations, depositing of calcium in blood vessels Signup and view all the answers

What is the main function of active vitamin D at the intestine?

Increases the absorption of calcium from the diet Signup and view all the answers

What is the principle function of vitamin D?

Maintain levels of calcium and phosphorus in the blood for nerve transmission, muscle contraction, and bone mineralization Signup and view all the answers

Study Notes

Vitamin A: Sources, Functions, and Deficiency

Vitamin A can be obtained from animal products, supplements, or plant foods, with the most common plant precursor being beta-carotene.
Vitamin A is essential for night vision, cell differentiation, and growth regulation.
Preformed vitamin A compounds are known as retinoids, while plant precursors are called carotenoids, with beta-carotene being the most common.
Retinoids and carotenoids are transported to the liver from the intestine in chylomicrons.
Different forms of vitamin A, such as retinol, retinal, and retinoic acid, have distinct functions in the body.
In the visual cycle, vitamin A, particularly retinal, combines with opsin to form rhodopsin, which is crucial for light perception in the eye.
Retinoic acid, a form of vitamin A, plays a role in gene expression and regulates the production of proteins.
Retinoic acid binds to specific protein receptors in the nucleus and alters the level of mRNA, thus regulating gene expression.
Vitamin A deficiency poses a threat to the health and sight of millions of children worldwide and is a major cause of blindness in resource-poor countries.
Vitamin A deficiency can result from insufficient intake of vitamin A, fat, protein, or zinc.
Excessive intake of preformed vitamin A can be toxic, and medications made from vitamin A can have serious side effects.
Vitamin A plays a crucial role in maintaining immune function and is involved in cranio-facial development, nervous system patterning, and organogenesis.

Vitamin A: Sources, Functions, and Deficiency

Vitamin A can be obtained from animal products, supplements, or plant foods, with the most common plant precursor being beta-carotene.
Vitamin A is essential for night vision, cell differentiation, and growth regulation.
Preformed vitamin A compounds are known as retinoids, while plant precursors are called carotenoids, with beta-carotene being the most common.
Retinoids and carotenoids are transported to the liver from the intestine in chylomicrons.
Different forms of vitamin A, such as retinol, retinal, and retinoic acid, have distinct functions in the body.
In the visual cycle, vitamin A, particularly retinal, combines with opsin to form rhodopsin, which is crucial for light perception in the eye.
Retinoic acid, a form of vitamin A, plays a role in gene expression and regulates the production of proteins.
Retinoic acid binds to specific protein receptors in the nucleus and alters the level of mRNA, thus regulating gene expression.
Vitamin A deficiency poses a threat to the health and sight of millions of children worldwide and is a major cause of blindness in resource-poor countries.
Vitamin A deficiency can result from insufficient intake of vitamin A, fat, protein, or zinc.
Excessive intake of preformed vitamin A can be toxic, and medications made from vitamin A can have serious side effects.
Vitamin A plays a crucial role in maintaining immune function and is involved in cranio-facial development, nervous system patterning, and organogenesis.

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Description

Test your knowledge of Vitamin A with this quiz on its sources, functions, and deficiency. Learn about the importance of retinoids, carotenoids, and different forms of Vitamin A, as well as the potential health risks associated with deficiency and excessive intake.