Biochem: Nutrition Flashcards
1
Q
vitamin A
BASICS
DEFICIENCY
EXCESS
A
retinol
basics
- antioxidant
- constituent of visual pigment
- imp for normal diff’n of epithelial cell into specialized tissue (pancreatic cells, mucus secreting)
- prevents squamous metaplasia
deficiency
- nyctalopia: night blindness
- xerosis cutis: dry scaly skin
- keratomalacia: corneal degen
- Bitot spots (conjunctiva)
- immunosuppression
excess
- ACUTE TOX: n/v, vertigo, blurry vision
- CHRONIC TOX: alopecia, ry skin, hep tox/enlargement, arthralgias, pseudotumor cerebri
***teratogenic!!! need neg preg test and 2x contraception before rx
- cleft palate
- cardiac abnl
2
Q
vitamin B1
BASICS
DEFICIENCY
- associated syndromes
- why def?
A
incorporated into thamine pyrophosphate (TPP), which is cofactor for lots of DHases:
- pyruvate DH (link from glycolysis to TCA)
- alpha0ketoglutarate DH (TCA cycle)
- transketolase (HMP shunt)
- BCketoacid DH
therefore…
deficiency
- impaired glucose breakdown → ATP depletion
- aerobic tissues affected first
- Wernicke Korsakoff syndrome
- ber1 ber1
why deficiency? alcoholism, malnutrition
3
Q
Wernicke Korsakoff syndrome
triad
other fts
damaged structures
A
B1 def
classic TRIAD
- confusion
- opthalmoplegia
- ataxia
- confabulation
- personality change
- memory loss (permanent)
damage to: medial dorsal nuc of thalamus AND mammilary bodies
4
Q
beri beri
2 versions & fts
A
B1 def
dry beriberi
- polyneuritis
- symmetrical muscle wasting
wet beriberi
- high output cardiac failure (dilated cardiomyopathy)
- edema
5
Q
B2
A
riboflavin
- component of FAD, FMN
- cofactors in redox reactions
DEFICIENCY
- cheilosis: infl of lips, scaling and fissures at corners of mouth
- corneal vascularization
6
Q
B3
A
niacin
- component of NAD+, NADP+ (redox rxns)
- derivative of Trp, needs B2/B6 for synth
- i.e. impaired Trp abs/reabs leads to deficiency
- Hartnup Disease : defective neutral aa transporter in PCT and enterocytes → pellagra-like sx
- used in tx for hyperlipidemia → lowers VLDL, raises HDL
DEFICIENCY
- glossitis
- pellagra: 3Ds
- dermatitis (broad collar rash/Casal necklace/C3-C4 dermatome)
- diarrhea
- dementia/hallucinations
- hyperpig of sun-exp limbs
- CAUSES: Hartnup, malignant carcinoid syndrome (incr Trp metabolism), INH (decr B6)
- tx: high protein diet, nicotinic acid
EXCESS
- facial flushing (PGs)
- hyperglycemia
- hyperuricemia/gout
7
Q
pellagra
causes
sx
tx
A
B3 deficiency
CAUSES
- Hartnup Disease : defective neutral aa transporter in PCT and enterocytes → pellagra-like sx
- malignant carcinoid syndrome (incr Trp metabolism)
- INH (drop in B6)
SX
- glossitis
- 3Ds
- dermatitis (broad collar rash/Casal necklace/C3-C4 dermatome)
- diarrhea
- dementia/hallucinations
- hyperpig of sun-exp limbs
TX: high protein diet, nicotinic acid
8
Q
B5
A
pantothenic acid
- essential component of CoA and fatty acid synthase
DEFICIENCY
- dermatitis
- enteritis
- alopecia
- adrenal insuff
9
Q
B6
A
pyridoxine
- gets conv to PLP (pyridoxal phosphate), a cofactor in…
- transamination
- decarboxylation rxns
- glycogen phosphorylase
- imp for synthesis of cystathionine, heme, niacin, histamine, nts (5HT, epi, NE, DA, GABA)
DEFICIENCY
- confulsions
- hyperirritable
- peripheral neuropathy
- sideroblastic anemias
10
Q
B7
A
biotin
- cofactor for carboxylation enzymes
- pyruvate carboxylase: pyruvate → OAA
- acetylCoA carboxylase: acetylCoA → malonylCoA
- propionylCoA carboxylase: propionylCoA → methylmalonylCoA
DEFICIENCY
- dermatitis
- alopecia
- enteritis
how? antibiotic use OR excessive ingestion of raw egg white
- avidin in egg whites binds biotin
11
Q
B9
A
folate
- leafy green vegs
- abs in jejunum
- small pool stored in liver (3-4mo)
- conv to THF
- imp for synthesis of N bases in DNA, RNA
DEFICIENCY
- seen in alcoholism, pregnancy, drugs (phynytoin, sulfonamides, MTX)
- macrocytic, megaloblastic anemia
- hyperseg PMN cells, glossitis
- NO NEURO SX
- labs show hi homoCys, lo MMA
deficiency in pregnancy? high risk of neural tube defects!!!
12
Q
B12
A
cobalamin
- synth by microbes, found in animal products
- bound to animal protein, then R-binder (mouth), then IF (duodenum), then absorbed in terminal ileum
- IF comes from gastric parietal cells
- cofactor (holds a methyl group) for…
- methionine synthase: homoCys → methionine AND methylTHF → THF (same set of rxns)
- methylmalonylCoA mutase: MMCoA → succinylCoA (later pushed into heme synth or TCA)
DEFICIENCY
- body has a store in the liver (years’ worth) but can get def via
- malabs (sprue, enteritis, Diphyllobthorium latum tapeworm)
- no IF (pernicious anemia or gastric bypass surgery)
- absence of term ileum (resection, Crohns)
- diet (vegan)
- sx:
- macrocytic megaloblastic anemia (hyperseg PMNs)
- NEURO SX: subacute combined degeneration of spinal cord
- dorsal columns, lat corticospinal tracts, spinocerebellar tracts → paresthesias, irrev nerve damage w prologed def
- due to hi homoCys and MMA levels
13
Q
megaloblastic macrocytic anemia with neuro sx
A
B12 deficiency
- body has a store in the liver (years’ worth) but can get def via
- malabs (sprue, enteritis, Diphyllobthorium latum tapeworm)
- no IF (pernicious anemia or gastric bypass surgery)
- absence of term ileum (resection, Crohns)
- diet (vegan)
megaloblastic anemia due to B12 def (with subacute combined degen)
- macrocytic megaloblastic anemia (hyperseg PMNs)
- NEURO SX: subacute combined degeneration of spinal cord
- dorsal columns, lat corticospinal tracts, spinocerebellar tracts → paresthesias, irrev nerve damage w prologed def
- due to hi homoCys and MMA levels
14
Q
C
A
ascorbic acid
- fruits/vegs
- fx:
- antioxidant
- facilitates Fe abs
- collagen synth: hydroxylation of Pro and Lys in collagen synth
- DA → NE: key for DA beta-hydroxylase
DEFICIENCY
- scurvy
- weakened immune resp
EXCESS
- n/v, diarrhea, fatigue
- Ca oxalate nephrolithiasis
- risk of Fe tox in predisp individs
15
Q
scurvy
A
vit C deficiency → defective collagen synth
- can’t hydroxylate Lys or Pro
- swollen gums
- bruising, petechiae, hemarthrosis
- anemia
- poor wound healing
- periifollicular and subperiosteal hemorrhages
- “corkscrew hair”
