Flashcards in Lecture 13 - Antioxidants Deck (54)
What is the role of antioxidants?
To protect cells from oxidative damage
What are the agents that protect from oxidative damage?
Vitamins quench the radicals
Minerals act as cofactors for enzymes
What is a free radical?
Something with an unpaired electron which damages lipids DNA RNA and proteins
What neutralizes free radicals?
What is the definition of quench?
To get rid of, eliminate
What can antioxidants be thought of?
Dominos, a vitamin would sit inform of the domino to prevent the others from following
Why are minerals required for antioxidants?
They themselves aren't antioxidants, but they are just required for the function
What creates free radicals?
Any normal reaction in the body
What are the available forms of vitamin A?
Retinyl Esters: True vitamin a
Beta Carotene: Precursor for vitamin a (not true)
Where are Retinyl esters in the body?
Bonded to fat in the body. Esters will separate from fat to just have retynil
What is the storage form of Vitamin a
What is retinol involved in?
How do we end up with retinal?
Retinyl (from animal foods) > Converted to retinol > converted into retinal
Beta-carotene (from plants) > Converted to retinal
In the body, what are the different conversions of all the retinoids?
Retinol< >Retinal> Retanoic acid
What happens when we have too much retinal?
It can be converted back to retinol
What is the hormone version of vitamin a?
-involved in DNA, transcription, Cell division, growth, reproduction
Do carotenoids all have the same antioxidant activity?
Yes, but not all of them are converted to vitamin a
What is the pathway for vitamin a once it has been ingested?
It is fat soluble and will end up in the chylomicrons then into the lymph and blood. Once in the blood it binds to binding proteins to be carried within the body
Where is vitamin a role in protein synthesis and cell differentiation
Takes place in epithelial cells on the skin and in the mucos membranes. Vitamin a is there to make sure those cells divide properly
-promotes differentiation of epithelial and goblet cells
How does vitamin a help with reproduction and growth?
Failure of growth in children
What does vitamin a deficiency look like?
Vitamin a status
What is vitamin a status?
Amount of vitamin a for you to use is dependant on how much is in your liver as well as your protein status
What happens to vitamin a when you don't have enough protein?
It won't transport vitamin a
What is vitamin a deficiency dependent on?
Vitamin a status and protein tatus
Where is vitamin a stored?
In the liver
What results from a vitamin a deficiency?
-Night blindness (lack of rhodopsin and inability to recover from changes in light)
-Xerophthalmia (total blindness due to drying and softening of cornea)
How does vitamin a toxicity occur?
When binding proteins in the blood become swamped, the vitamin isn't excreted quickly so the free vitamin a can cause damage
-not seen with beta-carotene
Why isn't vitamin a a treatment for acne?
Vitamin a itself is not used as a treatment for acne but the retinoid used to treat acne have no vitamin a activity
What are some sources of beta carotene?
-any vegetable really
Preformed vitamin a in any animal protein with some fat