Shared Flashcard Set

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Vitamins and coenzymes
USMLE
63
Medical
Graduate
05/01/2010

Additional Medical Flashcards

 


 

Cards

Term
What are the fat soluble vitamins?
Definition
A, D, E, K
Term
What are the 7 B vitamins?
Definition

B1-thiamine

B2-riboflavin

B3-niacin

B5- pantothenic acid

B6- pyridoxine

B7-Biotin

B12- cobalamin

Term
Which vitamins are antioxidants?
Definition
A, C, E
Term
Which two water soluble vitamins are not easily washed out like the others and why?
Definition
B12 and folate b/c they are stored in the liver
Term
Which vitamin if deficient can lead to night blindness?
Definition
Vitamin A
Term
Which vitamin in excess can be teratogenic causing cleft palate or septal defects?
Definition
vitamin A
Term
Who can you not give isoretinoin to? Why?
Definition

pregnant women

 

teratogenic

Term
What dose vitamin A do in the eye?
Definition
with opsin it helps maintain a closed Na channel in the rods
Term
What G protein does rhodopsin work through?
Definition
GT (transducin)
Term
What does GT activate in the eye?
Definition
PDE
Term
Are the photoreceptors hyperpolarized or depolarized when light is absorbed?  How is this accomplished?
Definition
hyperpolarized by closure of the Na channels through the action of PDE deceasing the concentration of cGMP
Term
What is the vitamin A derived medication used for wrinkles and acne?
Definition
retin A
Term
What enzymes is thiamine a cofactor for? (4)
Definition

pyruvate dehydrogenase

a-ketoglutarate dehydrogenase

transketolase

branched chain AA dehydrogenase

Term
What are the three diseases induced by thiamine deficincy?
Definition

wet beri beri (high output heart failure)

 

dry beri beri

 

wernicke korsakoff

Term
Why are the brain and heart most effected in thiamine deficiency?
Definition
Thiamine required in TCA cycle and glycolysis and therefore without it you cannot make enough ATP for the highly dependent tissues like the heart and the brain
Term
What vitamine deficiency disease manifests as an alcoholic patient with confusion and confabulation?
Definition
wernicke korsakoff
Term
What disease can present as polyneuritis and symmetrical muscle wasting after several years of heavy drinking?
Definition
dry beri beri
Term
What vitamin deficiency results in dry cracking lips and a dry cracked magenta tongue?
Definition
riboflavin deficiency
Term
What is cheilosis?  What vitamin deficiency is it seen in?
Definition

inflammation of the corner of the mouth

 

seen in riboflavin deficiency

Term
What vitamin deficiency can present with corneal vascularization?
Definition
riboflavin deficiency
Term
What vitamin deficiency presents with diarrhea, dermatitis, and dementia?
Definition
Niacin deficiency (pellegra)
Term
What amino acid can niacin be derived from if not enough in the diet?  What cofactor does it require?
Definition
Niacin can be derived from tryptophan and requires pyridoxine (B6)
Term
What is hartnup disease?
Definition
genetic disorder where there is inability to abosorb vitamins especially tryptophan
Term
What can hartnup disease lead to and why?
Definition
can lead to niacin deficiency-->pellegra due to deficiency in tryptophan
Term
How can malignant carcinoid syndrome cause pellegra?
Definition
increase the metabolism of tryptophan and therefore the precursor to niacin
Term
You have an AIDs patient present to you with symptoms consistent with TB, you treat him with isoniazid.  What two vitamin deficiencies is this patient at risk for?
Definition

primarily vitamin B6 (pyridoxine)

 

also niacin deficiency b/c B6 is required to convert tryptophan into niacin

Term
Niacin is found in corn grown in the US.  What would be the explanation for an individual presenting with diarrhea, dermatitis, and forgettfulness who eats alot of corn?
Definition
the corn is not treated and therefore the niacin is not able to be absorbed
Term
A 55 year old overweight male comes into the office with facial flushing that has been lasting ever since his last check up visit at which time his lipids were found to be too high.  At that check-up what lipid lowering drug was he most likely perscribed?
Definition
niacin
Term
What is the function of pantothenic acid?
Definition
component of CoA
Term
A 45 year old TB patient comes into your office complaining of fatigue and pale skin.  After a blood smear reveals a microcytic hypochromic anemia, you change his TB medication.  What was the cause of his anemia? and what type of anemia is present?
Definition

pyridoxine deficiency

 

causing sideroblastic anemia

Term
What vitamin is used in the synthesis of heme and specifically what enzyme in heme synthesis?
Definition
pyridoxine and the enzyme ALA synthase
Term
What vitamin is a cofactor in transaminase reactions?
Definition
pyridoxine (B6)
Term
What vitamin is used as a cofactor for glycogen phosphorylase?
Definition
pyridoxine
Term
What two enzymes is vitamin B12 a cofactor for?
Definition
homocysteine methyltransferase and methylmalonyl-CoA mutase
Term
What type of anemia results with a deficiency in cobalamin?
Definition
megaloblastic
Term
What is the difference in clinical presentation between folic acid deficiency and cobalamin deficiency?
Definition
cobalamin deficiency will present with paresthesia due to its neurologic effects on the posterior columns
Term
What vitamin deficiency presents with subacute combined degeneration in the spinal cord?
Definition
vitamin B12 deficiency
Term
What  autoimmune disease can cause B12 deficiency?
Definition
pernicious anemia
Term
Where is vitamin B12 absorbed specifically in the gut?
Definition
terminal ileum
Term
What vitamin deficiency can be found in a patient with Celiacs disease or crohns diseae?
Definition
B12 deficiency
Term
What vitamin deficiency can be associated with the fish tape worm Diphyllobothrium latum?
Definition
B12 deficiency
Term
What test is used to determine cause of vitamin B12 deficiency?
Definition
Schilling Test
Term
What vitamin is important in the production of purines and therefore DNA?
Definition
folic acid
Term
What is the most common vitamin deficiency in the US?
Definition
folic acid
Term
What cofactor is need for the conversion of NE to epi?
Definition
SAM
Term
What enzymes is biotin a cofactor for? (3)
Definition

the carboxylases

 

pyruvate carboxylase

acetyl CoA carboxylase

propioyl CoA carboxylase

Term
What vitamin is needed as a cofactor for the carboxylase reactions?
Definition
biotin
Term
What vitamin deficiency can you acquire from eating raw eggs?
Definition
biotin
Term
What in raw eggs leads to what vitamin deficieny?
Definition
avidin in egg whites leads to biotin deficiency
Term
A 20 year old man is looking to bulk up and resorts to a high protein diet.  He learns in a weight lifting magazine of a food he can eat to add to his protein intake. After the course of several years he is able to put on the extra muscle however to his surprise he is beginning to lose his hair.  What vitamin is he deficient in?
Definition
biotin
Term
What are the three functions of vitamin C?
Definition

cofactor for lysine and proline hydroxylase in collagen synthesis

 

cofactor for Dopamine B hydroxylase

 

keeps iron in reduced state to better its absorption

Term
What vitamin is necessary to keep iron in its reduced state to better its absorption?
Definition
vitamin C
Term
What type of infections can you see an increased amount of calcitriol in and why?
Definition
sarcodosis and other granulomatous diseases because they contain 1a hydroxylase activity
Term
What is the active form of Vit D?
Definition
1,25 dihydroxycholecalciferol (Calcitriol)
Term
What enzyme is required for Vit D synthesis in the liver?
Definition
25 hydroxylase
Term
What is the storage form of Vitamin D?
Definition
25 hydroxycholecalciferol
Term
What is the main function of Vitamin E?
Definition
antioxidant and prevent lipid oxidation (atherosclerosis)
Term
What can a deficiency in Vit E lead to with regards to RBC and why?
Definition

hemolytic anemia b/c RBC are especially suseptable to free radicals since they are always exposed to oxygen

 

w/o Vit E they have less antioxidant power

Term
What enzyme is vitamin K a cofactor for?
Definition
y-glutamyl carboxylase
Term
Where is Vitamin K synthesized?
Definition
in the intestine by the flora
Term
How can clindamycin lead to hemorrhage?
Definition
clindamycin is a broad spectrum antibiotic that can lead to decreased intestinal flora and therefore less production of vitamin K
Term
Why are infants given an injection of Vit K at birth?
Definition
b/c they have sterile intestines and inability to produce Vit K -->risk of hemorrhage
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