University (Questions & Answers)
True or False
Vitamins:
- cannot be made in the body
- noncaloric
- required in small amounts (mg and mcg) - ✔️ TRUE
Vitamins:
- cannot be made in the body
- noncaloric
- required in small amounts (mg and mcg)
What 3 forms can vitamin A take? - ✔️ - retinol (alcohol)
- retinal (aldehyde)
- retinoic acid (acid form from retinal)
What form of vitamin A is normally found in blood and tissues? - ✔️
Retinyl Palmitate
What form of vitamin A is found in plants? - ✔️ Previtamin A -
carotenoid structure that includes the carotenes and xanthophylls
- found in plants
- needs to be converted to active vitamin A
What is the most potent form of vitamin A? - ✔️ Beta carotene
Where can retinyl esters be found? - ✔️ Animal Products *only*
Where can vitamin A be found? - ✔️ Fortified milk and milk products
Where can previtamin A carotenoids be found? - ✔️ Plant sources -
orange and dark green vegetables
,Vitamin A containing micelles form and traverse the enterocyte plasma
membrane by what type of diffusion? - ✔️ Passive Diffusion
What two things are needed in the digestion of vitamin A? - ✔️ Bile
and Fat
Beta-carotene and other carotenoids can be converted to retinol by what
means? - ✔️ Beta-carotene and other carotenoids can be converted
to retinol by cleavage of the central double bond
When beta-carotene is cleaved, how many molecules of retinal does it make?
- ✔️ 1 beta-carotene = 2 retinal
Retinyl, retinyl esters, and carotenoids are packaged into what and
transported where? - ✔️ Retinyl, retinyl esters, and carotenoids are
packaged in *chylomicrons* and transported in the *lymphatic system*.
Vitamin A and carotenoids are metabolized where and as what? - ✔️
Vitamin A and carotenoids are metabolized in the liver as chylomicron
remnants.
Retinoic acid is absorbed and transported to which organ bound to what
protein? - ✔️ Retinoic acid is absorbed and transported to the liver
bound to albumin.
The liver stores 90% of which vitamin? - ✔️ vitamin A
What are the functions of vitamin A & Carotenoids? - ✔️ - Improves
vision
- Cell differentiation & cell proliferative activity
- Fights cancer
- Development of embryo tissue
- Synthesis of glycoproteins
- Reproductive processes
- Antioxidant capacity
- Bone development and maintenance
- Provides immunity
,How is vitamin A essential to our vision? - ✔️ - retinol is
transformed into 11-cis retinal through a series of reactions
- 11-cis retinal combines with the protein opsin forming rhodopsin
- Rhodopsin + light changes the conformation of the protein which begins a
cascade of events leading to the generation of an action potential
- This action potential sends neural impulses to the optic center of the brain
translating it into images
What are the 2 nuclear receptors that work with vitamin A on a molecular
level? - ✔️ RAR & RXR
Vitamin A is beneficial for all cancers but... - ✔️ lung cancer
Vitamin A is involved in sperm development and differentiation, without it,
what happens? - ✔️ Without RARγ, males are sterile
If a female is low or deficient in vitamin A, what could happen? - ✔️
deficiency: inability of implantation of the egg
low: may allow implantation but may end in a miscarriage; various birth
defects
Vitamin A is excreted in _____ & _____. - ✔️ Vitamin A is excreted in the
bile (70%) and urine (30%).
RDA of vitamin A for men - ✔️ 900 mcg/day
RDA of vitamin A for women - ✔️ 700 mcg/day
12 mcg beta-carotene = ??? mcg of retinol - ✔️ 12 mcg beta-carotene
= 1 mcg of retinol
Vitamin A deficiency is the leading cause of ___________ in children worldwide.
- ✔️ Vitamin A deficiency is the leading cause of *non-accidental blindness* in
children worldwide.
Diseases caused by vitamin A deficiency - ✔️ - night blindness
- xerophthalmia
- bitot spots
, Symptoms of vitamin A toxicity - ✔️ - decreased appetite
- dry, itchy, flaky skin
- headache
- hair loss
- bone/muscle pain
- ataxia
- nausea/vomiting
- dry mouth
- eye irritations
- conjunctivitis
- birth defects
- miscarriage
- learning difficulities
This unique vitamin is synthesized in the body with adequate sun exposure as
well as it's ability to function as a hormone. - ✔️ Vitamin D
What are the two forms of vitamin D? - ✔️ D2 - ergocalciferol
D3 - cholecalciferol
UV light converts __________ into cholecalciferol (D2). - ✔️ UV light
converts *7-dehydrocholesterol* into cholecalciferol (D2).
Aside from humans being able to produce their own amounts of vitamin D, it
can also be found in: - ✔️ - animal foods (eggs, liver, fatty fish, &
butter)
- fortified milk and dairy products
- fortified margarine
Vitamin D enters mucosal enterocytes by __________ diffusion. - ✔️
Vitamin D enters mucosal enterocytes by *passive* diffusion.
Vitamin D becomes part of __________ and then enters the __________ circulation.
- ✔️ Vitamin D becomes part of *chylomicrons* and then enters the *lymph*
circulation.
40% of vitamin D is transported in chylomicrons. The remaining 60% is
transported by what protein? - ✔️ D-binding Protein (DBP)