Podcast
Questions and Answers
What happens to the rhodopsin molecule when light falls on the eye?
What happens to the rhodopsin molecule when light falls on the eye?
What is the result of a severe vitamin A deficiency in the eye?
What is the result of a severe vitamin A deficiency in the eye?
What is the role of retinoic acid in the body?
What is the role of retinoic acid in the body?
What happens to epithelial tissue when vitamin A is deficient?
What happens to epithelial tissue when vitamin A is deficient?
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What is the consequence of vitamin A deficiency in the lungs?
What is the consequence of vitamin A deficiency in the lungs?
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What is the role of vitamin A in men?
What is the role of vitamin A in men?
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What is the function of retinoic acid in the body?
What is the function of retinoic acid in the body?
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Where is retinol, an active form of vitamin A, primarily stored in the body?
Where is retinol, an active form of vitamin A, primarily stored in the body?
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What is the function of beta-carotene in the body?
What is the function of beta-carotene in the body?
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What is the difference between vitamin A from animal-derived foods and plant-derived foods?
What is the difference between vitamin A from animal-derived foods and plant-derived foods?
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What is the role of vitamin A in the maintenance of body linings and skin?
What is the role of vitamin A in the maintenance of body linings and skin?
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Study Notes
Vitamin A
- Vitamin A was the first fat-soluble vitamin to be recognized
- Vitamin A and its precursor, beta-carotene, are still an area of research
Forms of Vitamin A
- There are 3 active forms of vitamin A: Retinol, Retinal, and Retinoic acid
- Retinol is an antioxidant nutrient stored in the liver
- Retinal is converted by the cells to retinol as needed
Roles of Vitamin A
- Gene expression
- Vision
- Maintenance of body linings and skin
- Immune defenses
- Growth of bones and of the body
- Normal development of cells
- Reproduction
Vitamin A in Eyesight
- Vitamin A plays 2 roles in eyesight: in the process of light perception at the retina and in the maintenance of a healthy cornea
- Rhodopsin, a pigment in the retina, contains vitamin A, which breaks off when light falls on the eye and reunites with the pigment after bleaching
- A lack of vitamin A can cause night blindness
Night Blindness
- Night blindness occurs when the vitamin A supply is low, causing a lag before the eye can see again after a flash of bright light at night
Xerophthalmia and Blindness
- A more profound deficiency of vitamin A causes keratinization of the cornea, leading to xerophthalmia (drying) and permanent blindness
- Half a million vitamin A-deprived children become blind each year due to xerophthalmia
Gene Regulation
- Retinoic acid, a form of vitamin A, regulates hundreds of genes that direct the synthesis of proteins that perform metabolic work in tissues
- Vitamin A affects the metabolic activities of tissues and, in turn, the health of the body
Cell Differentiation
- Vitamin A is needed for cell differentiation in epithelial tissue, such as the protective linings of the lungs, intestines, vagina, urinary tract, and bladder
- Cell differentiation is essential for the development of specific cell functions, such as mucus production in goblet cells
- Vitamin A deficiency leads to the failure of cells to make mucus, allowing keratin to accumulate and making tissues vulnerable to infection
Immune Function
- Vitamin A has an "anti-infective" reputation and is essential for immune defenses
- A lack of vitamin A weakens the body's defenses, making illness more severe
Reproduction and Growth
- In men, vitamin A is necessary for the formation of sperm
- Vitamin A is essential for reproduction and growth
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Description
Learn about Vitamin A, the first fat-soluble vitamin to be recognized, and its plant-derived precursor, beta-carotene, which has antioxidant activity. Explore their functions and food sources.
