Micronutrients I - Minerals Flashcards
Zinc excess
gastric distress, dizziness, nausea Emetic effect at doses as low as 50 mg Can reduce Cu absorption (Cu and Zn uptake related) implicated in alzheimer's disease can affect cholesterol and lower HDLs
Zinc deficiency
tissue damage - oxidative stress, apoptosis
immune deficiencies
late onset secondary sex chara.
growth reduction/ developmental changes
poor appetite - pts lose sense of taste
malabsorption disorders - inflammatory bowel disease
Iodine
require about 150 micrograms/day
concentrates in Thyroid
usually bound to tyrosine residues of proteins - regulates metabolic rates in cells
Iodine deficiency
spontaneous abortion
birth defects
irreversible impairment of brain and physical development
stimulates enlargement of thyroid (goiter)
Iodine excess
Mild excess (up to 2 mg/day) no apparent effects chronic excess can disrupt thyroid function
Selenium
enzyme cofactor for antioxidant defense thyroid hormone and insulin function regulation of cell growth and fertility Exists as selenomethionine and selenocysteine adults require about 55ug/day
Selenium deficiency
cardia failure liver disease cancer atherosclerosis hair loss skin changes infertility
Selenium Excess
>400 ug/day peripheral neuropathy nausea diarrhea dermatitis hair loss nail deformities
Homeostatic mechanisms act to maintain;
Optimal ionic strength
How do you estimate total body water (TBW)?
TBW (liters) = body weight (lbs) / 4
What are some macronutrients?
Water and salts
Minerals
Vitamins
What is a cofactor?
Organic (vitamins) or inorganic (metal) aids to enzymes
Selenium is said to be an antioxidant, but what is an issue that can arise because of this belief?
Selenium is toxic at high levels
Transcellular refers to…
Luminal fluid of GI tracts and CNS, fluid in eyes and lubricating fluids of serous membrane surfaces
Interstitial refers to…
Space between cells
Which is higher in the resting cell; K+ or Na+?
K+ (140 mM)
Osmotic equilibrium;
Extracellular fluid (ECF) osmolality = Intracell (ICF)
What is the particle concentration of a fluid called and what are it’s units?
Osmolality Millosmoles per kg
Normal extracellular concentration of Na?
145 mM
Normal Intracellular concentration of Na?
12 mM
Normal Extracellular concentration of K?
4 mM
Normal Intracellular concentration of K?
140 mM
Major ECF solutes?
Na+, Cl- and HCO3
Major ICF solutes?
K+, organic phosphate esters (ATP, creatine phosphate, phospholipids)
what molecule is responsible for most of the osmotic pressure in blood?
Albumin contributes to ~80%
whats a milliequivalent?
still not sure but slides say= milliMolar when only one ionizable group = 2x mMolar if there are TWO charges if there are multiple ionizable groups with diff. pK’s, it is more pH dependent
what is the normal osmolality of plasma ?
275-290 mosmol/kg
what is the recommended intake of sodium?
2400 mg/day
In 20% of the population is Na sensitive and can lead to . . .
hypertension (ECF expansion)
Which molecules regulate the effective osmolality of the ECF and the ICF respectively?
Na+, K+
What are the main macromolecules?
Sodium and potassium
When food is ingested, your cells become _____ so if you vomit you ____ solutes.
Isotonic, solutes
The GI tract to the jejunum ____ water and the jejunum to the colon ____ water.
Secretes, absorbs
What are the other important macromolecules?
Calcium, phosphorous, sulfer and magnesium
What are the functions of calcium?
Regulation of intracellular enzyme activities Secretory processes Blood clotting Muscle contraction Bone growth Binds to proteins Acts as second messenger Hormone receptor interactions Calmodulin Binding - regulates muscle contraction and inflammation
Calcium concentration higher inside or outside of a cell?
Intracellular calcium is ~0.1 uM
which is about 10,000x lower than the ECF
Example of symport
diffusion of H+ along gradient pulls along Lactose
How much water is lost with feces ?
100ml/day
why do you lose solutes if you vomit or have diarrhea?
ingested food/water become isotonic
diarrheal fluid is also close to being isotonic and can lead to loss of liters
Recommended K+ intake
3500 mg/day
Excess K+
cardiac arrest
K:Na ratio linked to hypertension
K+ deficiency
heart arrhythmia
muscle weakness
increased blood pH (alkalosis)
Example of Calcium acting in hormone receptor interaction
epi “fight or flight” hormone released from adrenal medulla. Binds to alpha receptors in liver, activates glycogenolysis and inhibits glycogen synthesis mainly by raising Ca+ levels in the liver
what promotes Ca+ absorption?
Vitamin D Gastric acid Lactose Citrate, malate Protein and phosphorous Exercise
What inhibits Ca+ absorption?
Oxalic acid and Phytic acid from plants Dietary fiber Phosphate (combines with Ca+ to make insoluble precipitate - stones) steatorrhea (fatty feces) (soaps) increased rate of passage
what can occurs due to Calcium deficiencies?
rickets, osteomalacia - adult rickets
Vitamin D prevents rickets - low leads to poor intestinal absoprtion/poor kidney reabsorption of Ca and Phosphate
Osteoporosis
Many metal-phosphates are extremely …
insoluble
Excessive Calcium intake leads to
risk of renal stone formation in some ppl
adult males should consume ~ _____ mg/day of calcium?
1000
What is the second most abundant mineral in the body?
Phosphate - (PO4)-3
where is most of the phosphate in the body ?
85% in bones and teeth
15% elsewhere - like nucleic acids
What regulates phosphate?
Vitamin D
what are some functions of phosphate?
in structure of nucleic acids phospholipids activation of enzymes by phosphorylation ENERGY - ATP acid-base balance
what are some dietary sources of Phosphate?
Animal protein, milk, eggs
Processed foods - tons of phosphate buffers
Food additive for pH adjustment, to sequester some thing (like metals)
what is the recommended daily intake of Phosphate?
700-1250mg/day
A high Ca:P ration promotes?
Ca excretion
15g/kg of diet is upper limit
What are some functions of Magnesium ?
Bone strength ATP hydrolysis - most enzymes need Mg+2 to stabilize ATP Enzyme cofactors Binds nucleic acids muscle relaxation after contractions
RDA for magnesium?
400mg/day male
300mg/day female
What are sources of Mg?
vegetables, nuts, legumes
~30-50% of intake is absorbed
Intracellular or extracellular Mg concentration higher?
intracellular
Mg deficiency
rare except with alcoholics
leads to hypertension, vascular disease. preeclampsia, osteoporosis
Mg excess
anaesthetic effect
diarrhea
function of sulfur?
sulfate in tissues
in AA - cysteine, methionine
key in disulfide bonds
role in transfer groups (Acetyl CoA)
Key metals in enzymatic activites and protein structure?
Iron
Zinc
Iodine
Selenium
Function of Iron
catalysis and electron transfer, oxygen transport
Why is Iron toxic in presence of oxygen ?
catalyzes Haber-Weiss-Fenton reactions
Haber-Weiss-Fenton reaction
Iron(II) + oxygen goes to Superoxide
Superoxide reacts with Hydrogen ions to make Hydrogen peroxide and oxygen
Iron(II) and hydrogen peroxide react to make hydroxyl radical (which attacks proteins) and hydroxide and Iron(III)
Zinc finger
protein domain that binds DNA for gene expression
cys, His, glutamate
Zinc
key role in many enzymes - catalysis and structure
Zinc fingers
Highly regulated by body
lose about 1mg/day
Unlike Fe, Zinc is NOT
redox reactive
What increases zinc absorption?
by binding to His, Cys and nucleotides
What decreases zinc absorption?
Phytate - attracts + metals
Metallothionein
Cys rich proteins bind many metals at high capacity (12 atoms per protein) - liver, stomach, brain, tongue
regulates Zn transfer in blood
what form of Zn is absorbed ?
Zn+2
Zinc storage
Men store 2.5 g
women 1.5 g
mainly in muscle and bone
Zinc turnover
300 days
very slow
In liver Zn-Mth is fast, ~2 weeks
units of trace metals in the body?
ppb - parts per billion = ug/liter
ppt - parts per trillion = ng/liter
