Hematopoetic vitamins and minerals Flashcards
1
Q
hematopoetic vitamins and minerals
A
- this groupd includes folic acid, vit b12 and fe
- both vitamins are involved in single carbon transfer as catalysts not donours
- Fe is involved in oxidation reduction reactions and in red blood cell metabolism
2
Q
Vitamin B12 cobalamin
A
- consists of a complex rinf structure than includes a cobalt ion at its centre
- the only metabolic function Co
- B12 is synthesized by bacteria and yeast. is absent in plant products
3
Q
absorption of B12
A
- intrinsic factor (IF) is secreted by parietal cells in the stomach
- in the duodenum B12 binds to IF
- the B12 intrinsic factor complex is transported into the epithelial cell
- B12 is released to reanscobalamin II for plasma transport
- stored in the liver
4
Q
metabolism of B12
A
- required co-factor for 2 reactions
- methylmalonyl CoA succinylcholine COA
Homocysteine - methionine
5
Q
B12 defiency
A
- B12 deficiency results in pernicious or megaloblastic anemia (large immature rbc in the blood)
- this effect is due to a deficieny of reduced folate
- B12 deficieny occurs as a heritable condition in humans caused by a lack of intrinsic factor
6
Q
folic acid
A
- required for DNA synthesis
- folate deficiency is the most common B vitamin deficiency in humans in North America
- abundant in plant sources including forages
- absorption transport storage and exretion are the same for thiamin
7
Q
so how do you tell a folic acid deficiency from a B12 deficiency
A
- folate is recycled of vit b12 is sufficient
- administer small amount of folate
- if this is effective, it was a folate deficiency
- in a B12 deficiency, folate will not be recycled so the added folate will have no effect
8
Q
cobalt requiremnt of ruminants
A
- rumen bacteria can synthesize vitamin B12
- they require Co to do this
- in grazing animals this is done using a cobalt-iodized saly block
9
Q
biochemical functions of Fe
A
- iron recognized as an essential nutrient for more than 100 years
- biochemistry of Fe is dominated by (low solubility and redoc characteristics)
- in aqueous, aerobic environments iron occurs as Fe 3
- in physical conditions occurs as both Fe3 and Fe2
- iron easily and reversibly undergoes the reaction
10
Q
iron absorption (inorganic)
A
- iron reduced to Fe2 in acid environments of stomach
- intestinal absorbtion requires divalent metal transporter 1 DMT1 can only be absorbed as Fe2
- regulation of DMT1 synthesis controls Fe absorbtion
- Fe is released to ferritin in cell and transported to the basolateral membrane
- feroportin tranports Fe2 across the basolateral membrane
11
Q
factors affecting Fe absorption
A
- inorganic Fe is poorly absorbed (2-5%)
- chelators such as citrate will chelate Fe increasing solubility and absorption
- some factos in plant ingredients can bind iron (phytates and tannin) decrease solubility and reduce absorption of Fe
12
Q
Fe absorption (heme Fe)
A
- heme is the active centre of hemoglobin RBC and myglobin muscle
- specific receptor absorbs heme iron complex so highly digestible
- absorbtion of heem iron (15-50%)
13
Q
hemoglobin
A
- consists of 4 globin chains (2 aloha and 2 beta)
- each globin binds one porphyrin molecule by coordinating the other two bonds on the central Fe atom
- each porphyrin ring can bind one molecule of 02
14
Q
Iron excretion
A
- virtually none (normal )
- hermorrhage can be a major route
- sloughing of intestinal epithelial cells is a minor route
15
Q
iron transport and storage
A
- body avoids free iron because it is so relative
- iron is associated with specific proteins for transport and storage
- transferrin - transport protein in blood
- ferritin - storage protein in liver, spleen and bone marrow
