GIT physiology 5 Flashcards
transcriptional regulators
vitamins A and D binds to receptors that form a transcriptional regulatory complex that changes gene expression
- vitamin D receptor is a transcription factor
- Retinoic X receptor is a transcription factor (vit A)
- vit K modifies existing proteins by adding carboxyl groups to increase activity
action of Vit K on transcription
modifies structure of existing proteins to increase their activity via glutamate residue carboxylation
ROS
reactive oxygen species
- proteins and sugars - glycation
- DNA - mutations
- membranes - lipid peroxidation
reactive oxygen species examples
OH, H2O2, O2
effects of ROS
- proteins and sugars - glycation
- DNA - mutations
- membranes - lipid per oxidation
vitamin classification
lipid soluble - A, D, E, K
water soluble - all others
lipid soluble vitamins
hydrophobic, absorbed with lipids using bile
- transported in blood in lipoproteins or attached to specific binding proteins
more likely to accumulate in the body and lead to toxicity hypervitaminosis
water soluble vitamins
8x B vitamins and vit C
- hydrophilic and dissolve in water
- not readily stored, excreted from the body
- does not cross plasma membranes, need carrier proteins
- consistent daily intake is needed and deficiency problems are common
- many types of water soluble vitamins are synthesised by bacteria and fungi, small amounts synthesised in GI tract
vit B1
thiamin
vit B2
riboflavin
vit B3
niacin
vit B4
pantothenic acid
vit B6
pyridoxine and pyridoxamine
vit B 7
biotin
vit B9
folic acid
vit B12
cobalamin
Vit C
ascorbic acid
thiamin
B1 used to form thiamin pyrophosphate coenzyme used in: - CHO and AA metabolism - DNA/RNA/neurotransmitter synthesis - TCA cycle
thiamin deficiency
problems with energy and neurotransmitter production
beriberi
deficiency of thiamin
- CNS problems: memory loss, confusion, ataxia (gait coordination)
- peripheral neuropathy - muscle weakness, muscle wasting
- wernickle-korsakoff syndrome - alcohol induced dementia
deficiency of thiamin is called
beriberi
toxicity symptoms of thiamin
no toxicity symptoms due to water solubility
wernickle-korsakoff syndrome
chronic alcohol use interferes with absorption of Vit B1
alcohol induced dementia
B1 chronic deficiency
riboflavin used to make
forms coenzyme flavin-mononucleotide (FMN) and flavin adenine dunucleotid (FAD)