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Gastroenterology5 > Vitamin Metabolism > Flashcards

Vitamin Metabolism Flashcards

(53 cards)

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1
Q

What are the two categories of vitamins based on solubility?

A

Water-soluble and fat-soluble vitamins

Water-soluble vitamins include all B vitamins and vitamin C; fat-soluble vitamins include A, D, E, and K.

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2
Q

List the fat-soluble vitamins.

A
  • A
  • D
  • E
  • K

These vitamins are absorbed and transported with dietary fat and stored in the liver and adipose tissue.

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3
Q

What are the main deficiencies associated with fat-soluble vitamins?

A
  • A
  • D
  • K

Deficiencies can lead to various health issues, including vision problems and bone disorders.

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4
Q

What are the main toxicities associated with fat-soluble vitamins?

A
  • A
  • D

Toxicities can lead to serious health issues, including increased intracranial pressure and organ damage.

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5
Q

Which lipoprotein affects the absorption of fat-soluble vitamins?

A

Chylomicrons

Chylomicrons transport dietary lipids to various tissues and organs.

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6
Q

What is the primary form of vitamin A found in animal tissues?

A

Retinol

Retinol is typically present as a retinyl ester with long chain fatty acids.

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7
Q

What is the role of retinoic acid in the body?

A

Morphogenesis, growth, and cell differentiation

Retinoic acid binds to nuclear receptors and regulates gene transcription.

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8
Q

What are the symptoms of vitamin A deficiency?

A
  • Xerophthalmia
  • Night blindness
  • Conjunctival xerosis
  • Bitot spots
  • Keratomalacia
  • Fatal infections

These symptoms indicate severe deficiencies which can impact vision and immune function.

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9
Q

What is a potential acute toxicity effect of vitamin A?

A

Increased intracranial pressure

Acute toxicity may also cause vertigo, diplopia, and seizures.

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10
Q

What is the active form of vitamin D?

A

1,25-dihydroxy-cholecalciferol (calcitriol)

This form regulates calcium and phosphorous levels in the body.

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11
Q

What is the primary function of vitamin D?

A

Regulates plasma levels of calcium and phosphorus

It stimulates intestinal absorption of calcium and reabsorption by the kidneys.

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12
Q

What deficiency condition is associated with vitamin D in children?

A

Rickets

Rickets leads to demineralization of long bones and characteristic deformities.

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13
Q

What is the primary role of vitamin E in the body?

A

Antioxidant

Vitamin E protects LDLs and polyunsaturated lipids from oxidation.

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14
Q

What are the symptoms of vitamin E deficiency?

A
  • Hemolytic anemia
  • Ataxia
  • Peripheral neuropathy
  • Proximal muscle weakness

Deficiency can be caused by conditions like cystic fibrosis and small intestinal resection.

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15
Q

What is the primary function of vitamin K?

A

Cofactor for post-translational γ-carboxylation of glutamate residues

This process is essential for the maturation of clotting factors.

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16
Q

Where is vitamin K primarily sourced from?

A
  • Green leafy vegetables
  • Margarine
  • Liver
  • Intestinal flora

These sources provide sufficient vitamin K for bodily functions.

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17
Q

What condition can result from vitamin K deficiency in neonates?

A

Hemorrhagic disease

This condition can lead to severe bleeding and requires vitamin K supplementation.

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18
Q

True or False: Vitamin D can be synthesized endogenously.

A

True

Vitamin D is synthesized in the skin upon exposure to UV light.

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19
Q

Fill in the blank: The vitamin D receptor is a type of _______.

A

nuclear receptor

The vitamin D receptor regulates gene transcription related to calcium metabolism.

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20
Q

What is the bioactive form of Water soluble vitamin B1?

A

Thiamine pyrophosphate (TPP)

TPP acts as a coenzyme for several dehydrogenase enzyme reactions.

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21
Q

What are the coenzymes involved in oxidative decarboxylation of α-keto acids?

A
  • Pyruvate dehydrogenase
  • α-ketoglutarate dehydrogenase
  • Branched-chain α-keto acid dehydrogenase

These enzymes are crucial in energy metabolism.

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22
Q

What are the major deficiencies associated with B1 (Thiamine)?

Study These Flashcards
A
  • Wernicke encephalopathy
  • Korsakoff syndrome
  • Beriberi Syndrome

Each condition has distinct symptoms and implications.

23
Q

What triad of symptoms is associated with Wernicke encephalopathy?

Study These Flashcards
A
  • Encephalopathy
  • Oculomotor dysfunction
  • Gait ataxia

This acute syndrome requires immediate medical attention.

24
Q

What is a significant dietary cause of Thiamine deficiency?

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A

Poor dietary intake, particularly in heavily rice-based diets

Rice is low in Thiamine, leading to deficiencies in at-risk populations.

25
What is the function of Water soluble vitamin B2 (Riboflavin)?
Cofactor for enzymes that catalyze redox reactions ## Footnote Examples include FMN and FAD.
26
What are the clinical findings associated with B2 (Riboflavin) deficiency?
* Dermatitis * Cheilosis * Angular stomatitis * Glossitis * Corneal vascularization ## Footnote These symptoms reflect the vitamin's role in skin and mucosal health.
27
What are the precursors of the coenzymes NAD+ and NADP+?
Nicotinic acid and nicotinamide ## Footnote These compounds are essential for redox reactions in metabolism.
28
What are the symptoms of Pellagra associated with B3 (Niacin) deficiency?
* Diarrhea * Dermatitis * Dementia * Death (the 4 D's) ## Footnote Pellagra is a severe deficiency condition requiring prompt treatment.
29
What is the function of Water soluble vitamin B5 (Pantothenate)?
A component of coenzyme A (CoA) and acyl carrier protein ## Footnote CoA is vital for fatty acid metabolism.
30
What are the structures of Water soluble vitamin B6 (Pyridoxine)?
* Pyridoxine * Pyridoxal * Pyridoxamine * 5'-phosphate derivatives ## Footnote These forms serve as precursors for the active coenzyme.
31
What are the functions of Pyridoxal phosphate (PLP)?
* Amino acid metabolism * Glycogen phosphorylase activity * Synthesis of neurotransmitters ## Footnote PLP acts as a cofactor for over 100 enzymes.
32
What drugs can induce peripheral neuropathy related to B6 deficiency?
Isoniazid (INH) and oral contraceptives ## Footnote These medications can interfere with B6 metabolism.
33
What is the primary function of Water soluble vitamin B7 (Biotin)?
Coenzyme for carboxylation reactions ## Footnote Biotin is crucial for metabolic pathways involving CO2.
34
What condition can avidin cause in relation to Biotin?
Prevents absorption of Biotin from the intestine ## Footnote Avidin is found in raw egg whites.
35
What are the functions of Water soluble vitamin B9 (Folate)?
* Converted to tetrahydrofolate (THF) * Amino acid biosynthesis * Purine biosynthesis * Thymidine biosynthesis ## Footnote Folate is essential for DNA synthesis and repair.
36
What is water soluble vitamin #7?
B9 (folate) ## Footnote Folate is essential for DNA synthesis and repair, and it plays a crucial role in cell division.
37
What are the main causes of B9 (folate) deficiency?
* Increased demand: pregnancy and lactation * Poor absorption: pathology of small intestine, alcoholism, treatment with certain drugs (e.g. methotrexate, phenytoin, sulfonamides) ## Footnote These factors can lead to insufficient folate levels necessary for cellular processes.
38
What are the consequences of B9 (folate) deficiency?
* Neural tube defects * Growth failure * Megaloblastic anemia with hypersegmented neutrophils ## Footnote Neural tube defects include conditions such as spina bifida and anencephaly.
39
What is megaloblastic anemia?
A deficiency of either folic acid or vitamin B12 causes accumulation of large immature RBC precursors, known as megaloblasts, in the bone marrow and blood. ## Footnote This condition is characterized by the presence of megaloblasts and can be linked to both B9 and B12 deficiencies.
40
What is the role of folic acid in the body?
Synthesis of purines and dTMP, which are essential for DNA synthesis and cell division. ## Footnote A deficiency in folic acid leads to reduced cell proliferation.
41
What is the significance of folate supplementation in women of child-bearing age?
Adequate folate nutrition must occur at the time of conception because critical folate-dependent development occurs in the first weeks of fetal life. ## Footnote This helps prevent neural tube defects in the developing fetus.
42
What is water soluble vitamin #8?
B12 (Cobalamin) ## Footnote Cobalamin is critical for various metabolic processes in the body.
43
What is the structure of B12 (Cobalamin)?
Corrin ring system with cobalt in the center of the corrin ring. ## Footnote The unique structure of B12 is crucial for its function as a cofactor.
44
What are the functions of B12 (Cobalamin)?
* Cofactor for Methionine synthase (re-methylation of homocysteine to methionine) * Cofactor for Methylmalonyl-CoA mutase (converts methylmalonyl-CoA to succinyl-CoA) ## Footnote These reactions are essential for amino acid metabolism and energy production.
45
What is the folate trap hypothesis?
In B12 deficiency, blocking of the methylation cycle causes folate to become trapped at 5-methyl-THF, leading to a pseudo folate deficiency and megaloblastic anemia. ## Footnote This explains why folate levels may appear normal while B12 deficiency persists.
46
Where can B12 (Cobalamin) be found in the diet?
* Liver * Red meat * Fish * Eggs * Dairy products * Fortified cereals ## Footnote B12 is primarily found in animal products and is not present in plant sources.
47
What conditions can lead to B12 deficiency?
* Seen in vegans * Malabsorption (elderly) * Pernicious anemia ## Footnote These conditions may impair the body's ability to absorb or utilize B12 effectively.
48
What is pernicious anemia?
Severe malabsorption of B12 due to autoimmune destruction of gastric parietal cells that produce Intrinsic Factors (IF). ## Footnote Intrinsic Factor is necessary for B12 absorption in the intestines.
49
What are the symptoms of B12 deficiency?
* Megaloblastic anemia with hyper-segmented neutrophils * Subacute combined degeneration * Paresthesias * Ataxia * Memory loss * Dementia * Severe weakness ## Footnote These symptoms highlight the neurological and hematological impact of B12 deficiency.
50
What is the diagnosis for B12 deficiency?
* ↓B12 * ↑Methylmalonic acid * ↑Homocysteine ## Footnote Elevated levels of methylmalonic acid and homocysteine are indicative of B12 deficiency.
51
What is water soluble vitamin #9?
C (ascorbic acid) ## Footnote Ascorbic acid is known for its antioxidant properties.
52
What are the functions of vitamin C (ascorbic acid)?
* Antioxidant * Facilitates iron absorption from the gut * Required for hydroxylation of proline and lysine in collagen synthesis * Required in the conversion of Dopamine to Norepinephrine ## Footnote These functions are vital for maintaining overall health and wellness.
53
What are the symptoms of vitamin C deficiency?
* Scurvy * Sore, spongey gums * Loose teeth * Fragile blood vessels * Perifollicular hemorrhages * Hemarthrosis * Impaired wound healing * Anemia ## Footnote These symptoms reflect the importance of vitamin C in connective tissue health and blood vessel integrity.

Gastroenterology5 (6 decks)

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