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CMBM Exam 2 > Minerals > Flashcards

Minerals Flashcards

1
Q

Fluid compartments in the body

A
  • intracellular
  • extracellular
  • interstitial
  • plasma
  • transcellular
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2
Q

Intracellular volume

A

24 L (60%)

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3
Q

Extracellular volume

A

16 L (40%)

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4
Q

Interstitial volume

A

11.2 L (28%)

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5
Q

Plasma volume

A

3.2 L (8%)

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6
Q

Transcellular volume

A

1.6 L (4%)

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7
Q

Osmolality

A
  • The particle (solute) concentration of a fluid
  • units are millosmoles per kg (mos-mol/kg)
  • ECF solutes (or osmoles) are very different from the ICF, due to the action of transporters and active pumps, and different permeability of different membranes
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8
Q

Major ECF solutes

A
  • Na+
  • Cl-
  • HCO3-
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9
Q

Major ICF solutes

A
  • K+

- organic phosphate esters (ATP, creatine phosphate, phospholipids)

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10
Q

Albumin

A
  • responsible for about 80% of the osmotic pressure of blood
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11
Q

Main macrominerals

A
  • sodium

- potassium

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12
Q

Sodium RDA

A
  • 2400 mg/day

- adults ~500 mg/day (estimated requirement)

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13
Q

Potassium RDA

A
  • 3,500 mg/day

- adults 2,000 mg/day (estimated requirement)

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14
Q

Causes of electrolyte imbalances

A
  • vomit
    • Ingested food/water becomes isotonic
  • Diarrhea
    • close to isotonic and can lose liters
  • urine
    • very variable; depends many factors
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15
Q

Macrominerals

A
  • Sodium
  • Potassium
  • Calcium
  • Phosphorous
  • Sulfur
  • Magnesium
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16
Q

Excess Sodium effects

A
  • 20% population Na-sensitive, can lead to hypertension (ECF expansion)
  • K:Na ratio linked to hypertension
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17
Q

Excess Potassium effects

A
  • cardiac arrest

- K:Na ratio linked to hypertension

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18
Q

Potassium deficiency

A
  • heart arrhythmia
  • muscle weakness
  • increased blood pH (alkalosis)
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19
Q

Functions of Calcium Ca ++

A
  • Regulation of intracellular enzyme activities
    • Second –messenger functions
    • Hormone-receptor interactions; epinephrine ‘fight or flight’ hormone released from adrenal medulla. Binds to α-receptors in liver, activates glycogenolysis and inhibits glycogen synthesis mainly by raising Ca++ levels in liver
  • Secretory processes (nerve conductance, pancreatic enzymes, milk protein release)
  • Blood clotting
  • Muscle contraction
  • Structure/growth of bones and teeth
  • Binds to many proteins, affecting their function
  • Intracellular [Ca] can be ~ 0.1 uM (~ 10,000x lower than ECF)
  • Calmodulin binding (regulates MANY proteins and processes such as muscle contraction, inflammation – you name it)
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20
Q

Absorption of Calcium Ca ++ promoters

A
  • vitamin D
  • gastric acid
  • lactose
  • citrate, malate
  • protein and phosphorous
  • exercise
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21
Q

Absorption of Calcium Ca ++ inhibitors

A
  • oxalic acid
  • phytic acid
  • dietary fiber
  • phosphate
  • steatorrhea
  • increased rate of passage
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22
Q

Calcium Ca ++ deficiencies

A
  • rickets, osteomalacia (adult rickets)
  • Vitamin D prevents rickets (poor intestinal absorption / poor kidney reabsorption of Ca and Phosphate)
  • Osteoporosis
  • Adult males should consume 1000 mg/day, adolescents, women need slightly more
  • Excessive intake increases risk of renal stone formation in some people
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23
Q

Phosphorous

A
  • Second most abundant mineral in body
  • 85% in bones and teeth, 15% elsewhere (e.g. nucleic acids)
  • Also regulated by vitamin D
  • Functions in structure of nucleic acids, phospholipids, activation of enzymes by phosphorylation, ENERGY (ATP)
  • Also acid-base balance
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24
Q

Phosphorous RDA

A
  • 700-1250 mg/day
25
Q

Magnesium Mg ++ Functions

A
  • Bone strength
  • ATP hydrolysis
  • Enzyme cofactors (also for structural reasons)
  • Binds nucleic acids
  • Muscle relaxation after contractions
  • Intake is well distributed in US food
  • about 30-50% of intake is absorbed
  • [Intracellular] > [Extracellular]
26
Q

Magnesium Mg ++ deficiency

A
  • relatively rare except with alcoholics (DTs – hallucination) – extent is not really known
  • hypertension
  • vascular disease
  • preeclampsia
  • osteoporosis
27
Q

Magnesium Mg++ toxicity

A
  • anaesthetic effects

- diarrhea

28
Q

Sulfur S

A
  • Sulfate in tissues, and sulfur containing amino acids methionine and cysteine
  • Key role in protein structure (Cys-S-S-Cys) disulfide bonds
  • Key role in transfer groups (Acetyl CoA!) – things are easily attached and removed to and from S
29
Q

Key metals involved in enzymatic activities and protein structure

A

• Iron (Fe)
* some metals like Fe tend to be very insoluble (hard to mobilize). Also, they can be very toxic in excess
• Zinc (Zn)
* Iron and zinc may be the ‘most important’ or at least most common
• Iodine (I)
• Selenium (Se)

30
Q

Iron function

A
  • key role in MANY enzymes – catalysis and electron transfer, oxygen transport
    • Despite critical functional role, only about 8 mg Fe in all the different enzymes
  • Highly toxic (and insoluble) in presence of oxygen – catalyzes the Haber-Weiss-Fenton Reactions
    • creates HIGHLY reactive hydroxyl radical that attacks proteins, lipids, EVERYTHING! and damages these molecules
  • Fe proteins create these toxins (by accident) and also defend against them (e.g. superoxide dismutase)
31
Q

Iron stored in:

A
  • ferritin and hemosiderin, mostly in liver
  • spleen
  • muscle myoglobin
  • bone marrow
32
Q

Iron stores

A

~ 3-4 grams Fe. Most (~2g) is in blood with hemoglobin

  • Avg male stores 500-1500 mg, avg female 300-1000 mg
  • iron overload disorders, body iron can reach 40-50 grams! Mainly in liver, spleen and bone marrow
  • Iron is VERY strictly regulated by the body to maintain a constant store
33
Q

Iron uptake

A
  • requires copper
    • presumably for a ferroxidase
      activity
  • uptake by Transferrin
    • Specific cell membrane receptors on target cells
    • Tf-receptor complex is internalized by receptor-mediated endocytosis
    • Fe is released by acidification*
    • Transferrin and receptor are recycled by exocytosis
    • There is another poorly characterized pathway for taking up Fe bound to heme
  • Note – many metals are very insoluble at pH 7, but most are very soluble in acid
34
Q

Iron RDA

A
  • at least 8 mg per day to maintain stores with a mixed diet
  • ages 11-18 require 12M and 15F mg/day
  • ages 19-50 require 10M and 18F mg/day
  • > 50 years require 10M and 10F mg/day
  • pregnancy requires 30mg/day
  • lactating requires 15mg/day
35
Q

Iron uptake inhibited by

A
  • phytate

- polyphenols

36
Q

Iron uptake promoters

A
  • vitamin C
  • organic acids
  • heme
37
Q

Iron excess

A
  • Hemochromatosis (hereditary defect)
  • Hemosiderosis – dietary overload (still genetic component)
  • Alcohol (particularly red wines) in excess
  • Children ingesting Fe supplements
  • Possible roles in etiology of heart disease
  • Oxidative stress
  • Decreases absorption of thyroxine, tetracycline, ciprofaloxacin, and others
  • Hereditary ataxias (Freidreich ataxia – defective frataxin –Fe can’t be exported from mitochondria)
  • Overall, the evidence is not yet clear on the role of moderately elevated Fe levels and chronic diseases
  • Again, the body maintains iron levels very vigorously
38
Q

Iron deficiency

A

• At least 1 billion people are anemic (abnormally low blood hemoglobin) to some extent, mainly due to dietary Fe deficiency
• Other causes
* Infection (Helicobacter pylori – ulcers)
* vitamin deficiencies, inflammation
• Fe deficiency can exacerbate other problems – e.g. lead poisoning, possibly b/c of increased expression of the DMT divalent metal transporter in response to low Fe

39
Q

Zinc Zn ++ function

A
  • key role in MANY enzymes – catalysis and structure, particularly proteins interacting with DNA (Zinc fingers), and thus gene regulation
  • Note that unlike Fe, zinc is NOT redox active (though it still may act in catalysis)
40
Q

Zinc uptake promoters

A

binding to:

  • Histine
  • Cysteine
    * Metallothioneins – key Cys rich proteins bind many metals at high capacity (12 atoms per protein)- liver, stomach, brain, tongue
    • Metallothioneins regulate Zn transfer into blood
  • nucleotides
41
Q

Zinc stores

A
  • Men store about 2.5g, women 1.5 g, mainly in muscle and bone
  • Turnover very slow, about 300 days
  • Turnover in liver Zn-Mth is fast, about 2 weeks – can be mobilized for dietary deficiency – but this is a small pool, only good for a week or so
  • You lose about 1 mg/day – depends on many things
  • Like Fe, homeostasis rigorously regulates Zn levels in body over wide range of intake levels
  • However, Zn levels are not clinically well-established yet
42
Q

Zinc Zn ++ deficiency

A
  • Specifics are not clear, but there are so many key enzymes which require Zn, that it is no surprise it affects almost everything
  • Tissue damage, (oxidative stress, apoptosis), immune deficiencies, developmental changes
  • Skin lesions, growth reduction, late onset secondary sex char
  • Poor appetite
  • Genetic deficiencies
  • Malabsorption disorders – inflammatory bowel disease
43
Q

Zinc RDA

A
  • ~11 mg/day (Males)

- ~8 mg/day (Females)

44
Q

Zinc Zn ++ excess

A
  • Gastric distress, dizziness, nausea
  • Emetic effect at doses as low as 50 mg
  • Can reduce Cu absorption (Cu and Zn uptake are related)
  • Implicated in Alzheimer’s disease
  • Can affect cholesterol and lower HDLs
45
Q

Copper functions

A

• Involved in iron uptake (copper deficiency → anemia)

46
Q

Copper excess

A
  • weakness
  • tremors
  • anorexia
  • organ damage
  • nausea
  • diarrhea
47
Q

Wilson’s disease

A
  • rare hereditary disorder where liver does not excrete excess copper into bile as normal; released into blood and accumulates
  • Begins after age 5 – brain damage, involuntary movements, even psychosis (~ ½ affected people)
  • In the other half, first symptoms are liver damage → hepatitis and cirrhosis. See gold or greenish gold rings in corneas
  • Requires lifelong treatment with Cu-binding drugs. Liver transplant can cure it
48
Q

Iodine functions

A
  • Essential to thyroid hormones affecting development, growth
    and metabolism
  • Typically bound to tyrosine residues of proteins – regulates metabolic rates in cells (glycolysis) among other functions
49
Q

Iodine RDA

A
  • 150 micrograms μg/day
50
Q

Iodine uptake

A
  • Taken up in gut, concentrates in thyroid
51
Q

Iodine deficiency

A
  • spontaneous abortion
  • birth defects
  • irreversible impairment of brain and physical development
  • In adults, deficiency stimulates enlargement of thyroid (goiter)
52
Q

Iodine excess

A
  • Mild excess (up to 2 mg/day) no apparent effects

– chronic excess can disrupt thyroid function (added to table Salt)

53
Q

Selenium functions

A
  • Enzyme cofactor for antioxidant defense, thyroid hormone and
    insulin function, regulation of cell growth, fertility
54
Q

Selenium RDA

A
  • Adults require about 55 μg/day
55
Q

Selenium deficiency

A
  • cardiac failure
  • liver disease
  • cancer
  • atherosclerosis
  • hair loss
  • skin changes
  • infertility
56
Q

Selenium excess

A 
>400 μg/day
– peripheral neuropathy
- nausea
- diarrhea
- dermatitis
- hair loss
- nail deformities
57
Q

Manganese, molybdenum, chromium, cobalt, nickel functions

A
  • These have been shown to have roles with some specific enzymes (though not always in humans), or shown to be essential for reasons not yet understood
58
Q

Other metals Probably required – functions unknown:

A
  • Boron
  • silicon
  • arsenic
  • tin
  • rubidium
  • germanium, etc

CMBM Exam 2 (13 decks)

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