Quiz 2 (A, B12, C, D, E) Flashcards
General characteristic of vitamins A, B12, C, E, &D Functions & metabolism of vitamins (A, C, E, B12) - know specific forms of vitamin A, D & E associated with each of these functions - Proteins associated with transport of vitamin A & E RDA (C, A) - Know how to convert IU units to mg for vitamin E Deficiency & toxicity associated with Vitamins A, C, and B12 Excretion of Vitamin A, D, E, & C
B12 general characteristics
Complex ring structure
Found commonly in meats (Does not occur in our body, but in our bacteria)
Only vitamin with metal (Cobalt)
B12 Absorption
HCl Separates b12 from food proteins. Combines with intrinsic factor in the stomach for absorption.
B12 Primary Functional Forms
5’-deoxyadenosylcobalamin
Methylcobalamin
B12 Diseases
Prevents megaloblastic anemia (Large amounts of folate can hide this)
Pernicious anemia is a condition where instrinsic factor is not made and B12 cannot be absorbed well.
Deficiency also causes nerve problems and fatigue
A General Characteristics
Fat Soluble
First vitamin isolated
1 ring with a carbon chain (provitamin has a 2nd ring) 15c
Provitamin is caroten form catchall
A Toxicity
High intake of preformed A can lead to dizziness nausea, headaches, coma, and even death. Can also cause birth defects in pregnant women.
High amounts of beta-carotene can cause skin discoloration
A Deficiency
Xerophtlamia: Night blindness in the most common deficiency symptom.
Transport of A
Circulates as retinol bound to retinol binding protein.
Transport of E
- Secreted from liver as a-tocopherol
- Solubilized by bile acids, absored by small intestinal epithelial cells, incorporated into chylomicrons, and transported via blood lymphatics.
- Sent to liver in chylomicron remnant
- Sent from liver packaged in VLDL
- Alpha-tocopherol transfer protein (ATTP, biologically active form)
- Excreted as tocopheronic acid
C Toxicity
Diarrha, Nausea, and stomach cramps. Can also cause the body to store too much iron.
Could lead to calcium oxalate kidney stones
Can cause false positives when testing waste products
C Deficiency
Scurvy: fatigue, depression, inflammation of gums, skin discoloration.
C General Characteristics
Antioxidant
Used to make collagen (wound healing)
Improves Iron absorption
Immune function
A Metabolism
Hydrolyzed by pepsin and other upper small intestine enzymes (pancreatic esterases) before absorption.
Retinol and carotenoids become part of micellar particls with other lipids and are taken into duodenal and jejunal cells for absorption
C Function
Collagen Synthesis
Carnitine Synthesis
Tyrosine Synthesis and catabolism
Neurotransmitter Synthesis (Serotonin)
E Function
Chain-breaking antioxidant Protects cell membranes Enhances immune response Regulates platelet aggregation Regulates protein kinase C activation
