Quiz 3 Flashcards
What does a Vitamin A deficiency cause?
night blindness OR xerophthalmia - dry eyes, (can cause of blindness)
How was Vitamin A deficiency cured over 2000 years ago?
liver or butterfat
Vit A exists as one of thee 3 forms:
an alcohol (retinol), an aldehyde (retinal), or an acid form (retinoic acid)
Vitamin A is found in:
some animal Fats and Fish oils
TF Vitamin A is found in vegetable oils.
F
Can Vitmain A be stored in the body?
yes
Where can Vitamin A be stored in the body?
liver
What is the precursor of vitamin A?
beta-carotene, a provitamin
Where is beta-carotene found?
plants, orange-yellow and dark green fruits and vegetables
TF Vit A is an antioxidant.
F.
TF Beta-carotene is an antioxidant.
T. Vit A is not
What is another name of a precusor of Vit A?
a provitamin
Major functions of Vit A:
formation of visual purple, epithelial differentiation (especially mucous secreting structures), bone remodeling, growth, reproduction, activation of cell membrane systems
This is related to Vit A and in visulal purple:
rhodopsin
rhodopsin contains:
retinal, which is removed with light
How is rhodopsin regenerated?
with retinol in the bloodstream
How does Vit A affect night blindness?
regeneration time is increased
Pathway of light:
light, eye, retinal cells (rods and cones), rhodopsin, opsin, retinal, signal to brain
Examples of retinal cells:
rods and cones
Light causes a change in:
rhodopsin to opsin and (trans) retinal, which is then released to signal the brain
What happens after retinal is converted back into its original, cis form?
rhodopsin is rebuilt
What vItamin is invovled in differentiation and proliferation of epithelial surfaces?
VIt A
What will happen if mucous secreting cells deteriorate?
insufficient eye lubrication, surface will keratinize leading to xerophthalmia
How is Vit A supplied to ppl in underdeveloped countries?
high dose supplements (60,000 RE) twice yearly to children, sugar may be added
What deficiency can cause follicular hyperkeratosis?
VIt A
RDA for Vit A?
900(male) to 700 (female) retinoal equivalents (RE)
1RE=
1 ug vitamin A or 6 ug of beta-carotene
1 ug vitamin A =
6 ug of beta-carotene
1 International Unit =
0.3 micrograms retinol
What foods contain preformed vitamin A?
liver, cream, butter, egg yolk
TF Vit A is very stable to cooking.
T
Food items with high Vit A content:
carrots, squash, sweet potatoes, peaches, apricots, cantoloupes, mangoes, papaya, broccolo, and spinach,
What it the Tolerable Upper Intake Level of Vit A for adults?
3000 ug/d
about 3 to 4 times the RDA
TF fat soluble vitamins cannot be stored in the body
F
high doses of vitamin A can lead to:
weight loss, stunted growth, hair loss, nausea, bone tenderness, enlarged spleen and liver
Vit A deficiency symptoms:
night blindness, keratinization of epi tissues, xerophthalmia, infections
Normal funcitons of Vit A:
vision, cell differentiation, immunity
teratogenic:
relating to or causing developmental malformations
VIt A deficiency during pregnacy can lead to:
fetal malformations, spontaneous abortions
Acute Vit A deficiency:
upset stomach, nausea, headaches, dizziness, muscle uncoordinations
Chronic Vit A deficiency:
liver damage, hair loss, bone/muscle pain, loss of appetite, dry skin and mucous membrane, hemorrhages, coma, death
What caused early Arctic explorers to die after eating polar bear liver?
Vit A toxicity, about 500,000 IU per oz
What is hypercarotenemia?
developing orange skin, from excess carrot intake
Name 2 Vit A derivatives:
13-cis retinoic acid (Isotretinoin) “Accutane AND trans-retinoic acid - “Retin A
13-cis retinoic acid (Isotretinoin) is aka:
accutane
trans-retinoic acid is aka:
Retin A, generic - Tretinoin - topical use
Accutane is cleared from the body in __ days
10
This drug can have serious side effects like birth defects:
accutane, oral medication
Retin A is used to treat:
acne, reduce wrinkles and sun damage
Vitamin D Deficiency can lead to:
Rickets
How was rickets treated in the past?
fish liver oils
Active ingredient of fish liver oils:
Vit D, look bow-legged
How do we obtain Vitamin D?
diet or 7-dehydrocholesterol in the skin following exposure to sunlight
vitamin D2 is ___ and derived from ___
ERGOcalciferol, plants
vitamin D3 ___ and produced here
CHOLEcalciferol, in animal tissues
Pathway of vitamin D:
hydroxylated in liver, then to kidney to form 1,25-dihydroxycholecalciferol (calcitriol, the most biologically active form)
How is Vit D transported to the liver?
bound to carrier protein in bloodstream
Once vit D is transported to the liver, what happens?
it is metabolized to 25-OH Vit D
What happens to 25-OH Vit D in the kidney?
metabolized to 1,25 (OH)2D
What is the active Vit D hormone?
1,25 (OH)2 D
A form of cholesterol is converted to this when exposed to sunlight:
cholecalciferol
Fxns of Vit D
regulates calcium and bone metabolism, intestinal absorption of ca and p, works with parathyroid gland to maintain ca and p levels in serum
deficiency of vitamin D leads to poor calcification of:
cartilage during bone development
poor mineralization of the osteoid in Vit D deficiency results in:
skeletal deformities
This can occur due to inadequate calcification following bone remodeling:
osteomalacia
vitamin D deficiency during tooth development can lead to:
enamel and dentinal hypoplasia
RDA for Vit D for infants to age 50:
5 ug of cholecalciferol
RDA for Vit D for adults over 50 years old:
10 ug (400 IU)
RDA for Vit D for adults over 70 years old:
15 ug (600 IU)
TF Many foods have large amounts of vitamin D.
F. few
main source of Vit D:
fortified milk, fish liver oils, and exposure to the sun (15 min per day)
TF vitamin D is toxic at high doses.
T
Upper Level of Vit D is
50 ug (2000 IU) per day (5-10 X RDA), higher levels may be safe for adults
What can overabsorption of calcium lead to?
Ca deposition (kidneys and other organs), metabolic disturbances and cell death
Vit E was originally isolated from
wheat germ oil
What Vit E derivative has the greatest activity?
a-tocopherol
What does Vit E need for efficient absorption?
fat
TF Vit E is an antioxidant.
T, limits free-radical reactions
Vit E resides in:
cell membranes to help protect them from oxidation
Fxns of Vit E:
helps to prevent fats from becoming rancid, increases the stability of cell membranes, protects polyunsaturated fatty acids and other oxygen sensitive compounds, protects Vit A
Where in the cell are damaged free radicals?
LBilayer
TF Vit E deficiency is common in humans.
F. rare
What is the usual cause of Vit E dficiency?
a congenital or malabsorption disease
Vit E deficiency generally presents with:
a slight decrease in red cell stability
What can lead to Vit E deficiency?
Malfunction in absorption
TF There will be more celllular damage to the membranes of RBCs without Vit E.
T
RDA for Vit E:
15 mg a-TE for men & women (1 mg = 1.5 IU)
Tolerable Upper Intake Level for Vit E:
1000 mg/d (1500 IU)
Foods VIt E is found in:
veg/ plant oils (1/2 u.s. intake)
TF? Animal fats have a lare amt of Vit E
F. almost non
Levels of needed Vit E are proportional to:
intake of polnsaturated fats
