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 promotion; differentiation & proliferation of cell, embryonic dev & organogenesis
isoretinin 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 softening & opaque cornea) -> permanent blindness
growth impediment, poor wound healing
birth defect
abnormal bone formation
hypervitaminosis A
liver toxicity, bone reduction
excess hyporetinin 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 i.e. 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
brittle bones i.e. 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