sodium

potassium

chloride

• maintain water balance
• neutralize charges
• establish ion gradients across membranes

Classification of minerals

• based on concentration of minerals
  • macrominerals
  • microminerals

• sulfer
• magnesium
• iron
• calcium
• phosphorus

Sulfur (in what form is it ingested? in what form is it lost?)

• intake as Cys and Met
• lost as sulfate

• CoA
• proteins (Cys, Met)
• taurine
• proteoglycans (as chondriotin sulfate)

• form complex with nucleotide
• cofactor for many enzymes

Form iron found in in the body

Hb

Mb

cyc

non heme iron proteins

Name trace elements

zinc

iodine

copper

selenium

• immune function
• wound helaing
• protein and nucleic acid biosyn. (ex: cofactor for alcohol dehydrogenase)
• taste and smell acuity
• growth and development

Major cofactor for many enzymes

• replace sulfur in Met
• cofactor for lipid peroxidase

Function of copper

• cofactor for lysyl oxidase

manganese

molybdenum

chromium

fluoride

•  unknown what it is for or how much
  • believed to affect insulin function, thereby affecting metabolism

Location in body of 99% of calcium. what form is it found in?

• protein bound (half of it, mainly to albumin)
• chelated (bound to various anions or organic molecules)
• free ionized calcium (physiologically important fraction that is functional)

80% found in the bone

membrane phospholipids

nucleic acids

nucleotides

sugar phosphates

• SP = calcium conc. X phosphate conc.
• at homeostasis in plasma, the calcium and phosphate are near saturation
• if their is an increase that exceeds the solubility product, calcium and phosphate will precipitate separately

• bile (eventually be part of feces)
• urine
• sweat

Location of calcium. mech of absorption

Agents that decrease absoprtion of calcium

• fatty acids
• phosphate
• oxalate
• phytate (found in plants, cereal)
• alkali

decrease uptake/absorption

• calcium could be filtred into kidney
  • reabsorbed in distal convoluted tubule (phospate reabsorbed at PCT)
  • excreted in urine

• stores majority of calcium, leading to ossification (osteoblasts)
• can release calcium back into blood, leading to bone resorption via osteoclasts

osteoblasts

kidney

• decrease resoprtion of phosphate at proximal tubule (increase phosphate excretion)
• increases reabsorption of calcium and magnesium at DCT
• increase activity of alpha 1-monooxygenase

• promote resorption
  • inhibit collagen synthesis in osteoblasts
  • stimulate osteolysis by osteoclasts
    • increase number of osteoclasts
    • enhance lysosomal activity

• starts in skin as 7-dehydroxycholesterol
• UV light breaks one of the bonds on one fo the hexene rings to form pre-vit D3
• isomerization (switching of double bonds) leads to formation of Vit D3
• since not soluble in aqueous solution, we transport Vit D3 to liver via blood

skin

liver

kidney

Effect of liver on Vit D3

• Liver has 25 monoxygenase
• converts Vit D3 to 25 hydroxyvitamin D (add OH to aliphatic chain)
• tranpsorted to kidney via blood bound to transport protein

• kidney has alpha 1 mono-oxygenase (activity controlled by PTH) at the PCT
• converts 25 hydroxyvitamin to caclitrol (adds OH to hexane ring

1. diffuse into nucleus
2. binds to VDR and RXR on the DNA
3. has affect on gene transcription (can either enhance or silence transcription)

• intestines
• bone
• prostate
• mammary gland
• hemopoietic tissue
• parathyroid tissue

1. parathyroid senses decrease in calcium in plasma
2. stimulated to produce and secrete PTH
3. goes to kidney and bone
   1. in kidney
      • via cAMP mechanism, decrease reabsorption of phosphate (increase excretion) at PCT
      • increase reabsorption of calcium at DCT
      • increases activity of alpha one monooxygenase (increase production of calcitriol)
   2. in bone
      • PTH bind to osteoblast, causin it to "raise up" off the bone (stop ossification)
      • when osteoclast bound by PTH, releases factor to activate osteoclasts
      • osteoclasts will increase lysosomal activity and release their lysosomal contents
      • calcium will leave bone, picked up by transport protein, carried to plasma

• when we start to put calcium into the blood, if we dont bring phosphate down, we will get precipitation because we will exceed Solubility product
• if we get rid of phosphate, bringing it down to similar levels of calcium, when we start putting calcium into blood, we bring both back up together, preventing from exceeding solubility product

Role of GI tract when PTH released

• increase bound calcium
• frees up phosphate
  • in brush border, we turn on enzymes (ex: phytase increase free phosphate)
  • these enzymes increase calcium

• activates one alpha monoxygenase

• tetany
  • increase neuronal membrane permeability with progressive excitability

muscle paralysis

coma

death

• in children, causes rickets
  • bow leggedness
  • ricketa rosery (knots along rib cage)
• in adults, causes osteomalacia (type of osteopenia)

• scurvy- deficient matrix, but we have bone mineral
• rickets- deficient mineral, but we have matrix 
• with scurvy, you will see bleeding of the gums

• with osteoporosis, lost bone density and mineral
• with osteomalacia, you lose bone mineral, but not bone density

• decrease CaBP
• decrfeaser Ca transporter
• decrease phytase
• decrease phosphatase

We have a small amount of PTH and calcitrol in plasma at all times. Why