IAS10 Flashcards
purpose of micronutrients
Form prosthetic groups of enzymes or serve as their cofactors
Hormones
Cell growth, proliferation and differentiation
coenzyme
organic compound that binds with an enzyme to catalyse a reaction
vitamin vs mineral
vitamin: essential non-caloric INORGANIC
mineral: essential non-caloric ORGANIC
broad classification of vitamins
lipid soluble: ADEK
water soluble: C, B6;
energy releasing: B1,2,3,5,7
haematopoietic: B9,12
broad deficiency & excess cause of micronutrient
inadequate intake (malnutrition), increased demand (pregnancy, lactation, growth spurt), poor absorption from GI tract (old age), inefficient utilisation, inc. excretion loss
excess caused by excess supplement intake
fat v water soluble vitamin
fat: absorbed into lymph alongside fat w/ help of bile salts -> into blood, transport by carrier proteins & receptors
water: absorbed directly into blood, B12 requires transport proteins
fat: surplus stored in liver/fat tissues, hypo- rare, hyper- common, intake required in wks
water: not stored, excess excreted, hypo- common, hyper- rare, intake required in day
vitamin A types & function
4A: beta-carotene antioxidant
retinal for vision in dim light (produces rhodopsin) (aura),
retinoic acid for proper differentiation & maintenance of epithelial cells & growth promotion (activation); growth, differentiation & proliferation; embryonic dev & organogenesis
isoretinoin treat severe acne
vitamin A in sight (OPTIONAL)
vitamin A in corneal epithelium & retina
produces rhodopsin -> conformational change when exposed to light -> elicit nerve impulse, recognized by brain as light
vitamin A in cell differentiation (OPTIONAL)
retinoic acid (nuclear hormone) binds to transcription factor -> activates transcription of some genes -> cellular differentiation
hypovitaminosis A
night blindness
keratomalacia (defective epithelialization & corneal formation, cornea soften & opaque) -> permanent blindness
growth impediment, poor wound healing
birth defect, abnormal bone formation
hypervitaminosis A
liver toxicity, bone reduction
excess isoretinoin teratogenic i.e. disrupt fetal dev. & cause abnormal preg -> birth defect e.g. cleft palate, abnormal heart
vitamin D generation & conversion into active form
7-dehydrocholesterol -> (sunlight) cholecalciferol / D3
(note: 15 min sunlight give adequate intake)
ergocalciferol / D2 & D3 obtained in diet
D3 -> 25-(OH)-D3 in liver, -> 1,25-(OH)2-D3 in kidney i.e. active form, calcitriol
vitamin D function
Ca uptake: increases plasma Ca levels by increasing Ca absorption from GI tract / renal reabsorption, mobilization from bone -> restore plasma Ca levels
hypovitaminosis D
hypo- due to above reasons & poor functioning of the liver & kidneys, hypoparathyroidism, lack of sun exposure
rickets in children, osteomalacia in adults
hypervitaminosis D
hypercalcemia, Ca deposition in organs esp. joints, arteries & kidney -> hypercalciuria, kidney stones
vitamin E & deficiency
tocopherol for antioxidant (protect cells from ROS effect)
hypo: mostly in premature infants, adult cause due to defective lipid absorption / transport (CF, abetalipoproteinemia)
Haemolytic anaemia (no antioxidant -> RBC susceptible to rupture by ROS –> haemolysis) among others: retinopathy, neurological & neuromuscular dysfunction
ROS
reactive oxygen species: unstable & reactive -> damage biomolecules & cells
vitamin K function & property
4C: clotting factor, crushed by warfarin, cofactor of gamma carboxylation, cannot find in newborn infant
diet K (phylloquinone) -> active K (hydroquinone)
glutamate residue -> (by gamma carboxylase) active clotting factor & active K -> K epoxide; -> diet K
warfarin (anticoagulant) inhibit conversion of diet K into active K
newborn infant have sterile gut -> no K -> normalize when food absorption starts
hypovitaminosis & hypervitaminosis K
hypo- occurs in disruption of lipid absorption, anticoagulant taken, in premature infants
susceptible to bleeding & bruising, Anaemic, weak, heavy menstruation, nose, gums & GI bleeding
hyper- DNE except in prolonged intake of synth. K (menadione), liver toxicity & haemolytic anaemia
vitamin B functions
TRNPPBFC The Really Nice Parrots Prefer Big Fruits Carefully
Essential for normal metabolism
Coenzymes in many reactions in carbohydrate, fat & protein metabolism
Vitamin B1 & deficiency
thiamine: carb metabolism, coenzyme of pyruvate DH & OGDH in TCAC
hypo: reduced ATP production -> impaired cellular function –> beriberi / wernicke-korsakoff syndrome in chronic alcoholics
Vitamin B2 & deficiency
riboflavin: forms FMN & FAD (coenzyme for succinate DH (TCAC); acyl CoA DH; retinal dehydrogenase; complex I (ETC)
FAD & FMN coenzyme for vitamin-activating enzyme
hypo: skin lesions
VItamin B3 & deficiency
niacin: forms part of NAD+ (e- carrier from TCAC to ETC)
hypo: pellagra in skin, GI tract & NS -> diarrhoea, dementia, dermatitis, death (4D)
Vitamin B5 (can skip)
pantothenic acid: acetyl-CoA component