Exam 2 Flashcards

B12 -digestion and absorption -functions -causes of deficiency, deficiency disease/symptoms Vitamin C - Functions - Sources - Deficiency disease/symptoms - RDA & UL General characters of fat soluble vitamins Vitamin A: Sources Digestion, absorption, storage - transport - Hypervitaminosis - Function Specific retinoid associated with each function - Deficiency symptoms/disease - UL - toxicity - RAE - calculation - Carotenoids Vitamin K -Sources - Function - Vitamin K c

1
Q

B12 absorption and digestion

A

HCl Separates b12 from food proteins. Combines with intrinsic factor in the stomach for absorption.

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2
Q

B12 functions

A

Methylcoblamin: Used as a co-enzyme to convert homocysteine to methionine.

Adenosylcobalamin: required for methylmalonyl CoA mutase which converts L-methylmalonyl CoA to succinyl-CoA

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3
Q

B12 deficiency disease, symptoms, and causes

A

Prevents megaloblastic macrocytic anemia (Large amounts of folate can hide this)
Pernicious anemia is a condition where instrinsic factor is not made and B12 cannot be absorbed well.

Causes: impaired pancreatic exocrine function which impairs B12 release. Impaired gastric and intestinal function, parasitic competition, use of Nitrous oxide

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4
Q

C function

A

Antioxidant; hydroxylating enzymes involved in synthesis of collagen, carnitine, norepinephrine.

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5
Q

C sources

A

Papaya, OJ, cataloupe, broccoli, brussels sprouts, green peppers, grapefruit juice, strawberries.

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6
Q

C deficiency disease and symptoms

A

Scurvy: fatigue, depression, inflammation of gums, skin discoloration.

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7
Q

C RDA + UL

A

RDA / UL
Men: 75mg
Women: 90mg
Smokers:

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8
Q

A sources

A

Liver, dairy, sweet potato, carots, spinach, butternut squash, greens, broccoli, cantaloupe

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9
Q

A Digestion and absorption

A

Hydrolyzed by pepsin and other upper small intestine enzymes (pancreatic esterases) before absorption.
Retinol and carotenoids become part of micellar particls with other lipids and are taken into duodenal and jejunal cells for absorption

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10
Q

A storage and transport

A

Circulates as retinol bound to retinol binding protein.

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11
Q

A deficiency symptoms and diseases

A

Xerophtlamia: Night blindness is the most common deficiency symptom.

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12
Q

A UL and toxicity

A

High intake of preformed A can lead to dizziness nausea, headaches, coma, and even death. Can also cause birth defects in pregnant women.

High amounts of beta-carotene can cause skin discoloration

3,000 mcg (10,000 IU) = UL

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13
Q

A Functions and associated retinoid

A

Synthesis of rhodopsin and other light receptor pigments; metabolites involved in growth, cell differentiation, bone development, and immune function.

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14
Q

K sources

A

Synthesized by intestinal bacteria; green leafy vegetables, soy beans, beef liver

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15
Q

K function

A

Activates blood clotting factors by gamma(?)-carboxylating glutamic acid residues; carboxylates other proteins.

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16
Q

K cycle

A
-Quinone 
(quinone reductases: dithiol or NADPH)
-Dihydroquinone
(y-glutamyl carboxylase)
-2,3 epoxide
(epoxide reductase)
-Quinone
17
Q

K deficiency and UL

A

Deficiency is associated with hemorrhaging. There is no UL, but the synthetic form (Menadione) has been shown to cause liver damage in large amounts (also hemolytic anemia).

18
Q

E active forms, dietary form, and supplements

A

a-tocopherol (active)
y-tocopherol
Supplements can be gamma (y)-tocopherol or tocotrienols

19
Q

E transport

A
  • Secreted from liver as a-tocopherol
  • Solubilized by bile acids, absored by small intestinal epithelial cells, incorporated into chylomicrons, and transported via blood lymphatics.
  • Sent to liver in chylomicron remnant
  • Sent from liver packaged in VLDL
  • Alpha-tocopherol transfer protein (ATTP, biologically active form)
  • Excreted as tocopheronic acid
20
Q

E sources

A

Vegetable seed oils

21
Q

E toxicity and deficiency

A

Deficiency symptoms include: myopathy (skeletal muscle pain, anemia, and neuropathy

Toxicity: reduced clotting

22
Q

E RDA and UL

A

UL = 1500 IU, 1000mg a-tocopherol

RDA 15mg alpha-tocopherol

23
Q

E RDA and UL

A

UL = 1500 IU, 1000mg a-tocopherol

RDA 15mg alpha-tocopherol

24
Q

Lack of intrinsic factor can lead to what disease?

A

Pernicious anemia

25
How are fat soluble vitamins primarily excreted?
Bile to feces
26
Active form of vitamin D?
Calcitriol
27
Storage form of A?
Retinyl ester
28
Retinoid form importan to visual cycle?
11-cis retinal
29
Retinoid form for cell differentiation
retinoic acid
30
RAE for A
1 RAE = 1ug retinol = 12ug B-carotene = 24 a-carotene
31
Vitamin important to proline or lysine hydroxylation
C
32
Plant origin vitamin D
Cholecalciferol
33
Synthetic vitamin e forms
all rac-a-tocopherol