Iron, Zinc and Iodine Flashcards
What are the amounts of micronutrients needed?
ug or mg
Are micronutrients essential? Why?
- Not synthesized at rates sufficient to meet requirements
- Perform specific biological functions
- If withdrawn, deficiency occurs
Compare reversible and irreversible vitamin A deficiency.
Reversible: night blindness
Irreversible: blindness
Name the pigment that is non-essential.
Beta-Carotene, nothing happens if withdrawn
Define bioavailability.
% mineral ingested that is available for absorption
How is bioavailability highly variable?
Absorption can vary with need (ex: iron - 5%-50%)
Name 3 characteristics of bioavailability.
1) Potential toxicity from excess
2) Metabolic interactions (transporting)
3) General function in metalloenzymes or at least metalloproteins
Give an example of how micronutrients can function in metalloenzymes.
In redox reactions
Name the most abundant minerals.
Calcium -> phosphorus -> potassium -> sulphur -> sodium -> chloride -> magnesium
Name the minerals that are electrolytes.
Potassium, sodium, chloride
Which minerals appear in amounts higher than 1/2 a kilogram?
Calcium and phosphorus
What is free calcium used for?
Nerve impulse transmission
Where is calcium kept?
99% in bones
Where is iron mostly circulating?
Red blood cells
Define vitamins.
Essential organic nutrients required in small amounts
Which vitamin was first discovered?
Vitamin B1: Beriberi
Define vitamers.
Different forms of a vitamin that can have different functions, conversion between forms and from precursors
What is the general function of vitamins?
As coenzymes
Name the fat soluble vitamins.
A, D, E, K
Name the water soluble vitamins.
B complex, C
Vitamins are subject to what in food?
Degradation (light, oxygen, temp)
Why is there no vitamin F?
Whatever was proposed as vitamin F turned out not to be essential
Why are there so many vitamin Bs?
They thought it was just one compound, pulled out, found 12 different ones
What are the B vitamins essential for?
Intermediary metabolism
What is vitamin B1?
Thiamin
What is vitamin B2?
Riboflavin
What is vitamin B3?
Niacin
What is vitamin B5?
Pantothenic acid
What is vitamin B6?
Pyridoxine
Which B vitamins is the RDA based on energy?
B1 to B5
Which B vitamins is the RDA based on protein?
B6
How would an enzyme function without its coenzyme?
Wont catalyse, inactive, no chem reaction
Name 2 hormonal functions of vitamins.
- Vitamin A as retinoic acid - cell differentiation
- Vitamin D as calcitriol - Ca availability
Name an antioxidant function of vitamins.
Vitamin C and E -> lipid soluble, protect lipid membranes from fatty acids being oxidized
Define hypochromic.
Low in colour red cells
Define microcystic.
Small, low hemoglobin
How are the red blood cells in iron deficiency?
Hypochromic and microcystic
How are the red blood cells in folate or vitamin B12 deficiency?
Megaloblastic or pernicious anemia
Name examples of structures made from amino acids but are NOT a protein.****
- Heme
Define the structure of hemoglobin.
- 4 protein units, each has a disk, each has an iron
What is the function of myoglobin?
Muscle storage of oxygen
What is the main function of iron?
Carries oxygen
How do we diagnose iron deficiency anemia?
1st stage: serum ferritin
2nd stage: serum iron falls and transferrin increases
3rd stage: hemoglobin decreases
Name the signs and symptoms of iron deficiency anemia.
- Weakness, fatigue, headaches
- Decreased work performance and cognitive function
- Pale skin, nail beds, mucous membranes, and palm creases
- Concave nails, inability to regulate body temperature, pica
- Decrease in childhood development (psychomotor and intellectual)
Why does iron deficiency anemia increase lead poisoning susceptibility?
Fe2+ ressembles Pb2+
There is a transporter for the +2 cation, if someone is iron deficient the adaptation is to increase the efficiency of the absorption from the intestine, there is an increase in those active transporters, less competition from iron, more efficient iron of lead
What hemoglobin concentration indicates iron deficiency anemia in men? Women?
Men: Hgb < 140 g/L
Women: Hgb < 120 g/L
Compare the prevalence of iron deficiency in developed vs. developing countries.
Developing: 50% women + children, 25% men
Developed: 7-12% women + children
What percentage of low income infants in Montreal have iron deficiency?
25%
How many people worldwide have iron deficiency anemia?
4-5 billion people
What should iron metabolism be if an individual is healthy?
Iron intake = Iron losses
Describe free iron.
Toxic (oxidative stress)
Describe iron metabolism.
Learn it
How do you make Heme?
Fe2+ and protoporphyrin
How many transfer sites does transferrin have?
6
How long do circulating RBCs live?
120 days
What makes feces brown and urine yellow?
Bilirubin
In what state does iron function in?
2+ state
Compare Fe2+ and heme sources in terms of absorption.
Fe2+ : not well absorbed (10%)
Heme: up to 50% absorbed
Why does vitamin C help iron absorption?
It is a reducing agent: Fe3+ to Fe2+ = more absorbed
What substances will decrease iron absorption?
Coffee and tea