Minerals

Question 1

Calcium

Answer 1

Provides the structure to bones and teeth and has important regulatory roles
Also found in intracellular fluid, blood, and extracellular fluid- plays a role in nerve transmission, muscle contractions, blood pressure regulation and the release of hormones
Active transport accounts for most Ca absorption (when intakes are low or moderate)
Active vitamin D is required for active transport by increasing the numbers of transport proteins needed for transporting Ca across the enterocyte
Regulation of Ca: low Ca levels stimulates release of parathyroid hormone (stimulates release of Ca from bone by activating osteoclasts, reduces a Ca excretion by kidney, increases enzyme responsible for the last hydroxylation step to produce active vitamin D) & high Ca levels stimulates release (acts of osteoclasts to inhibit their activity, so release of Ca from bone decreases)
Regulate enzyme activity
Necessary for blood clotting
Chemical and electrical signals in nerves and muscles
Cell cycle and proliferation
Cell differentiation
Muscle contraction - actin and myosin interaction
Neuronal function (neurotransmitters)
Glandular secretion (hormone release)
Glycogen synthesis pathway

Question 2

Calcium Deficiency

Answer 2

If Ca intake inadequate, normal blood levels are maintained by resorbing Ca from bone
This can lead to low bone mass
Ca deficiency during years of bone formation results in less bone density
During adult years, results in increased bone loss

Question 3

Calcium Toxicity

Answer 3

Elevated blood Ca levels can cause loss of appetite, nausea, vomiting, constipation, frequent urination
Severe elevations can cause confusion, delirium, coma, death
Most often caused by elevated PTH
Too much Ca from supplements can promote kidney stones

Question 4

Bone

Answer 4

During bone formation, osteoblast activity exceeds osteoclast activity
Most bone formed early in life
Bones: support and protect, reservoir or store of minerals, buffering of excess acid loads, calcium regulation of homeostasis, source of new RBCs and immune cells, source of stem cells for fat, muscle bone
Osteoporosis - caused by a loss of both the protein matrix and the mineral deposits of bone, resulting in a decrease in the total amount of bone (risk factors include age and gender)

Question 5

Phosphorus

Answer 5

Important component of molecules with structural or regulatory roles
Forms hydoxyapatite crystals with Ca for strong bones
Component of water-soluble head of phospholipid molecules
Major constituent of DNA and RNA
Essential for energy metabolism - ATP
Component of creatine phosphate - provides energy to exercising muscles
Regulates enzymes as activity can be turned on or off by phosphorylating or dephosphorylating
Part of the phosphate buffer system that helps regulate pH in cytosol of cells
Deficiency can lead to bone loss, weakness and loss of appetite

Question 6

Magnesium

Answer 6

Essential for the maintenance of bone structure
Cofactor for enzymes - necessary for the generation of energy from carbohydrate, lipid and protein
Stabilizes ATP
Deficiency is rare but occurs in individuals with alcoholism, malnutrition, kidney and GI disease or in people taking diuretics (may cause, nausea, muscle weakness and cramping, mental derangement and changes in BP and heartbeat)

Question 7

Sulfur

Answer 7

Sulfur-containing amino acids (methionine and cysteine) are needed for protein synthesis
Vitamins thiamin and biotin contain sulfur