Magnesium Flashcards

1
Q

Where is magnesium found in the body?
How much of it is free?

A

Majority in skeleton, then soft tissues: usually bound to ligands and molecules
1% extracellular fluid where 0.6% is free

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2
Q

Magnesium acts primarily as

A

stabilizer and complexer for organic phosphates and nucleic acid

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3
Q

Mg is essential for aerobic and anaerobic metabolism. Which essential functions does this include?

A

Cellular energy metabolism (lipid and carb)
Nucleic acid and Protein syn
2nd Messenger system
Ion channel (stabilizer)

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4
Q

How does Mg differ from calcium

A

large hydrated volume which makes it not as flexibly in t’s binding state, though still competitive
- in water will increase “hardness”

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5
Q

How is mg involved in ATP/ADP

A

Stabilizers the Phosphate tails

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6
Q

Functions of Mg in glycolysis

A

activate enzyme, involved in energy making / using
makes substrates less available by temp binding

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7
Q

How is Mg involved in Protein syn

A

bind specifically to the phosphate group on nucleic acids for activity and for stabilization - prevent damage and degradation

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8
Q

Mg as a secondary messenger: Adenylate cyclase

A

Adenylate cyclase: G-protein bound to activate (w/GTP), to enhance interaction, to drive cAMP link, to provide energy for Kinase A

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9
Q

Mg as a secondary messenger: IP3

A

Provides substate for PIP2
Inverse relationship b/w [Mg] and IP3 activation
Drives Protein Kinase C step

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10
Q

Mg for ion channels

A

Needed to pump K out of cells (actively and passively)
ATP synthase

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11
Q

Food sources of Mg

A

high - legumes, green leafy veg, nuts, unpolished grains
Moderate - meat, fruits, dairy

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12
Q

RDA / AI for Mg

A

Infants: 30-75 AI
Men: 400-420 mg/d
Women: 310-360 mg/d
- Need more when growing - 14-18
- more when pregnant b/c of wt gain

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13
Q

Absorption of Mg

A

30-50% absorbed - entire intestine but mainly in ileum and lower J.
More is absorbed when you eat less (inverse relationship - tightly reg)
Proteins + Fiber can decrease absorp

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14
Q

Why would absorption of Mg not be a problem if body gets deficient?

A

Its a passive and active absorption system

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15
Q

Best absorption: Carbonate, Citrate, Glycinate, Malate

A

Citrate (18% - 90 bioavail)
Glycinate (18% - 80)
Malate (6.5% - 70)
Carbonate (45% - 30)

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16
Q

Excretion of Mg

A

Kidney - 70% of Mg filtered is free = increase reabsorption
75-90% reabsorbed in proximal and thick ascending tubules
***Requires K to be RE-absorbed

17
Q

Why would hypokalemia happen if Mg was deficient ?

A

keep trying to reabsorb which uses K+, which could cause K deficiency

18
Q

Why would hypocalcemia happen if Mg was deficient ?

A

PTH req adenylate cyclase = less PTH = less serum calcium = less absorption

19
Q

How would unmanaged diabetes and unmanaged BP affect Mg

A

Causes for decreased uptake
Diabetes: cause glucose in tubules = excess urine, less uptake (osmotic diuresis)
BP: high BP the body would respond by removing solvent / ANP = Pressure diuresis

20
Q

What else could cause mg deficiency

A

depletion = secondary disease
GI malabsorption, Vomit, Diarrhea
Kidney dysfxn
Chronic electrolyte imbalances