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46 Cards in this Set

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Obj.
List water soluble vitamins:
In general, how are they stored/absorbed in the body?
Vit B1,2,3,6,12
Vit C
Folate
Panthotenic acid
Biotin

Absorption: through intestines
Storage: only B12 & B6 can be stored, rest cannot
Obj.
List lipid soluble vitamins:
In general, how are they stored/absorbed in the body?
Vit A
Vit D
Vit E
Vit K

Absorption: absorption through lipids, packaged in chylomicrons
Storage: in liver or adipose tissue
Obj.
Main function, coenzymes, etc

Vitamin A (retinol, retinal, retinoic acid)
function:
Vision- retinal part of rhodopsin in rod & cone cells
Cell signaling- retinoic acid binds to intranuclear receptors & modulates genes expression
- maintanence of epithelium (infection protection), spermatogenesis, embryonic dvlpmnt

* dark-green, leafy veg, animal liver products
Vitamin A (retinol) toxicity
*due to excess vitamin supplements
-dry skin, mouth sores, loss of appetite, vomiting, hepatomegaly, liver failure
-teratogen (avoid excessive amounts if pregnancy is planned)
Vitamin A (retinol) deficiency
-impaired vision
mild: night blindness
severe: complete blindness due to keratinization of epithelial cells
-increased frequency of infections
decreased integrity of epithelium, leading to more pathogen invasions
Obj
Role of Vitamin A in vision cycle
-beta-carotene is used to produce all-trans-retinal
-all-trans-retinal is converted to 11-cis-retinal
-11-cis-retinal is combined w/ opsin producing rhodopsin
-->light photon acts on rhodopsin & signal is passed through optic nerve
(rhodopsin converted back to all-trans-retinal)
Obj.
Main function, coenzymes, etc

Vitamin D
Function:
-increases calcium absorption from intestine
-decreases renal calcium excretion
-mobilizes calcium from bones
= maintains plasma calcium levels
Describe Vitamin D homeostasis
-Dietary Vitamin D3, taken into chylomicrons & absorbed into lymph, provitamin D3 in skin is converted to Vitamin D3 upon UV exposure, both sources of Vitamin D are stored in liver
-Hydroxylated 25(OH)2D3 enters circulation and may come into contact with PTH in the kidney
-PTH causes further hydroxylation to 1,25(OH)2D3, this form increases bone Ca2+ release--> increasing plasma Ca2+
-PTH is secreted in response to low plasma Ca
Vitamin D deficiency
soft, pliable bones (bow leg)
children: rickets
adults: osteomalacia
Vitamin D toxicity
-loss of appetite, nausea, thirst, stupor
-hypercalcinemia (calcium deposits in kidney & arteries
Obj.
Main function, coenzymes, etc

Vitamin E (tocopherols)
Function:
*main fat-soluble antioxidant of human body
-protects membrane-lipids from free radical damage
Vitamin E (tocopherol) deficiency
-hemolytic anemia in premature infants (tocopherol stores not yet formed)
-nerve damage in older children & adults (myelin damaged)
Obj.
Main function, coenzymes, etc

Vitamin K
Function: blood coagulation
Coenzyme for: synthesis of y-carboxylglutamate (essential for Ca2+ binding to proteins)
Precursor for: glutamate carboxylation

*inhibited by Warfarin (anti-coagulant, antagonist of vit K)
*from intestinal bacteria, green leafy veg
Vitamin K deficiency
bleeding in newborns (intestinal bacterial flora has not yet formed)
-newborns receive Vit. K injection at birth

Bleeding may occur in adults if bacterial flora is killed by antibiotics
Obj.
Main function, coenzymes, etc

Vitamin B1 (thiamine)
*thiamine-pyrophosphate (active form_
Coenzyme for:
-pyruvate dehydrogenase (acetyl-CoA production)
-alpha-ketoglutarate dehydrogenase (TCA)
-alpha-ketoacid dehydrogenase (branched AA degradation)
(^oxidative decarboxylations)
-transketolase (pentose phosphate pathway)
Vitamin B1 (thiamine) deficiency
neurological symptoms (bc pyruvate dehydrogenase and a-ketoglutarate dehydrogenase are important for energy source for brain)

*def assayed through RBC transketolase activity
Berberi:
-infantile form: tachycardia, vomiting, convulsion
-adult form: dry skin, irritability, disorderly thinking, progressive paralysis

Wernicke-Korsakoff syndrome (chronic alcoholism):
-alcohol impairs thiamine absorption from intestines
-apathy, loss of memory, confusion, inability to move eyes

Deficiency can be assayed via RBC transketolase activity
Differentiate between the following Vitamin B1/Thiamine deficiencies:
Berberi
Wernicke-Kosakoff Syndrome
Berberi:
-severe thiamine deficiency
-infantile, tachycardia, vomiting, convulsion
-adult, dry skin, irritability, disorderly thinking, progressive paralysis

Wernicke-Kosakoff Syndrome:
-chronic alcoholism impairs intestinal thiamine absorption
-apathy, loss of memory, confusion, inability to move eyes
Obj.
Main function, coenzymes, etc

Vitamin B2 (Riboflavin)
-coenzyme in FMN & FAD form, used in ox-red
Vitamin B2 deficiency
rare!
cheliosis (cracked lips at corners), dermatitis, glossitis (purple smooth tongue)

*Pharm- used to lower cholesterol, reduces lipolysis in adipose, reduces TG, VLDL, LDL
Obj.
Main function, coenzymes, etc

Vitamin B3 (niacin)
-precursor for NAD & NADP
*can be subsituted by tryptophan

*used as a drug for high cholesterol, reduces lipolysis in adipose & TG, VLDL, LDL, in blood
Vitamin B3 deficiency
pellagra (Four D's: dermatitis, diarrhea, dementia, death)
Vitamin B3 toxicity
skin flushing, itching, tingling, burning sensation on skin
Obj.
Main function, coenzymes, etc

Vitamin B6 (pyridoxine)
*pyridoxal phosphate (active form)
-coenzyme for:
heme synthesis, transamination, deamination, decarboxylation (dopamine, histamine, serotonin, GABA synthesis)

*Isoniazid, anti-tuberculosis drug depletes pyridoxal-phosphate
Vitamin B6 deficiency
rare!

hyperirritability, neuritis, convulsions
Vitamin B6 toxicity
rare! from excess supplements

nerve damage
Obj.
Main function, coenzymes, etc

Vitamin C (ascorbic acid)
-collagen synthesis
-neurotransmitter synthesis (DOP-->NORE)
-tyrosine degradation
-antioxidant
Vitamin C deficiency
bleeding, bruising, delayed wound healing, loose teeth

extreme: scurvy
Vitamin C toxicity
intestinal problems, diarrhea
Obj.
Main function, coenzymes, etc

Panthotenic Acid
-precursor for CoA
(palmitoyl-CoA, acetyl-CoA, acetoacetyl-CoA, succinyl-CoA)

*def rare, no toxicity
Obj.
Main function, coenzymes, etc

Biotin
-coenzyme in carboxylation reactions

*bioavailability, corn & soy, some in wheat
Vitamin B8 (Biotin) deficiency
rare!
(avidin in egg white binds strongly, making unavailable

*no toxicity
Differentiate btwn the roles holocarboxylase synthase & biotinidase

What enzyme deficiency causes multiple carboxylase deficiency?
holocarboxylase synthase-
botin + enxyme ---> enzyme-biotin (covalent link)

biotinidase-
enzyme-biotin---> biotin + enzyme

Deficiency in EITHER causes multiple carboxylase deficiency
Main function of the following trace element:

Iron
-part of heme (chelated to prophyrin ring) & non heme proteins (iron-sulfur clusters)
(60-80% in hemoglobin)
-toxic if not bound to proteins
Explain the role of the following enzymes in iron metabolism:
Hepcidin
Ferritin
Ceruloplasmin
Transferrin
Hepcidin- regulates absorption in liver

Ferritin- iron storage in liver (as Fe3+)

Ceruloplasmin- controls oxidation (converts Fe2+ to Fe3+ allowing storage)

Transferrin- transports Fe3+ (albumin transports Fe2+)
Iron deficiency
Anemia
Iron toxicity
hemochromatosis (iron overload), liver and pancreatic damage, heart problems, arthritis, impotence
Main function of the following trace element:

Copper
-necessary for the stability of ceruloplasmin

*transported in circulation 90% by ceruplasmin (10% albumin)
Differentiate btwn the following copper transporters
CRT1
ATOX1
ATP7A
ATP7B
CRT1- membrane transporter
ATOX1- intracellular transporter (chaperon)
ATP7A- intestinal pump, ATP dependent
ATP7B- liver pump, ATP dependent
Diseases of copper metabolism
Menkes Disease (deficient ATP7A):
Deficient Cu INTESTINAL UPTAKE
neurological effects, growth retardation, hypopigmentation, laxity of skin
TX- copper-histadine

Wilson's Disease (deficient ATP7B):
Deficient Cu EXCRETION;
cirrhosis, liver failure, neurological defects, psychiatric symptoms
TX- copper restricted diet, chelators, oral zinc

*both lead to low blood ceruloplasmin
Main function of the following trace element:

Zinc
-essential for many enzyme/protein functions
-wound healing, skin integrity, spermatogenesis, pancreatic function

*stored in metallothioneine (high levels induce production of metallothioneine)
Zinc deficiency
Acrodermatitis enteropathica (deficient zinc transporter):
red and inflamed patches of dry, scaly skin that becomes blistered lesions; hair loss; diarrhea
Main function of the following trace element:

Iodine
thyroid hormone synthesis
Iodine deficiency
Goiter (lack of iodine in diet --> enlarged thyroid gland)

Cretinism (mother lacked iodine intake during pregnancy --> mental and growth retardation)
Main function of the following trace element:

Selenium
-present in selenocysteine & selenomethionine
Selenium toxicity
brittle nails and hair, intestinal problems, garlic-like body odor, neurological problems
Selenium deficiency
Keshan disease (China): cardiomyopathy