Dr. Siham Gritly 1

Physiological roles of minerals

Dr. Siham Gritly

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glossary• extracellular fluid: fluid outside the cells.

Extracellular fluid includes two main components; the interstitial;- fluid between cells usually high in sodium and chloride and the intravascular fluid of plasma. Extracellular fluid accounts for approximately one-third of the body’s water.

• Interstitial fluid: fluid between the cells (intercellular), usually high in sodium and chloride. Interstitial fluid is a large component of extracellular fluid.

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• Ions; atoms or molecules that have gained or lost electrons and therefore have electrical charges. Examples include the positively charged sodium ion (Na+) and the negatively charged chloride ion (Cl–).

• Cations; positively charged ions.• Anions; negatively charged ions.• electrolytes: salts that dissolve in water and

dissociate into charged particles called ions.• electrolyte solutions: solutions that can conduct

electricity.

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Homeostasis -a term used to describe a condition of normalcy in the internal body environment

• Osmotic pressure- is the amount of pressure required to oppose osmosis (water movement) into a solution across semi-permeable membrane.

• Osmosis is the movement of water across a semi-permeable membrane

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Chemical symbols of major minerals

• K = potassium• P = phosphorus• Mg = magnesium• S = sulfate• Na = sodium• Cl = chloride• Fe = iron

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Cations (positively charged ions) of human fluids

• Cation;

-a positively charged ion or electrolyte; sodium, potassium, calcium and magnesium (extracellular fluid)

sodium, potassium, magnesium (intracellular fluid)• Sodium (Na+)• Potassium (K+)• Calcium (Ca++)• Magnesium (Mg++)

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Anions (negatively charged ions) of human fluids

Anion;

-a negatively charged ion or electrolytes; chloride, bicarbonate, phosphate, sulfate, protein and organic acids (extracellular fluid). chloride, bicarbonate, phosphate and protein (intracellular fluid)

• Chloride (Cl−)• Bicarbonate (HCO3−)• Phosphate (HPO4=)• Sulfate (SO4=)• Organic acids (lactate, pyruvate)• Proteins

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Minerals • Are inorganic regulators needed for different functions inside the

body.

• Do not provide energy but involved in generation of energy through their metabolic function

• provide a good medium for the protoplasmic activities (permeability of cells membrane and normal functioning of the cell, irritability of muscle and nerve cells

• maintaining body fluid balance (osmotic pressure)• regulation of acid-base balance• for structural units (bones and teeth• haemoglobin and thyroxin formation• some are cofactors in the enzymatic reactions

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Physiological functions of minerals

• growth and development (used in building blocks for body tissues such as bones, teeth, muscles or act as main components of hemoglobin)

• They are found in compounds essential for the functioning of the body, e.g., iodine in thyroxin, zinc in insulin, Cobalt in Vitamin B12, sulphur in thiamine and iron in hemoglobin.

• As constituents of soft tissues, such as tissue protein, cell bodies and muscles, they are responsible for their proper functioning.

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• metabolic regulation; include enzymes known as metalloenzymes such as the cytochrome enzymes in mitochondria that facilitate ATP production

• and other as zinc and copper which are part of the natural antioxidant enzymes

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• As constituents of body fluids, • They contribute to the osmotic pressure of

body fluids.

• Sodium salts and potassium salts are present in the intracellular fluids that influence their osmotic pressure.

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• maintenance of neutrality in blood and body tissues, this is by;

• preventing the accumulation of too much acid or alkali.

• The chief base forming elements are sodium, potassium, calcium and magnesium.

• The acid forming elements are chlorine, phosphorus and sulphur.

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• Calcium, Potassium and Sodium maintain the normal rhythm in- heart beat.

• They help nerves in maintaining a normal response to stimuli-especially by Calcium.

• They are essential for clotting of blood. Calcium is responsible for clot formation.

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• Minerals classified into;• 1-macrominerals; required in excess (100mg/day);

sodium, magnesium, phosphorous, sulfur, chlorine, potassium and calcium

• 2-microminerals; required in less than 100mg/day

essential trace elements are manganese, iron, cobalt, nickel, copper, zinc, selenium,, and iodine additional to boron, chromium, fluoride, and silicon.

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Electrolytes

• Electrolytes are the electrically charged minerals that when dissolved in water or another solvent, forms or dissociates into ions (electrically charged particles conduct electric current).

• Electrolytes are distributed throughout the fluid compartments of the body. The solution is known as electrolyte solution

• Common electrolytes are bases, acids and salts

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the major electrolytes are in body fluids are sodium, potassium, chloride, bicarbonate, sulfate, magnesium and calcium.

• When dissociate form ions particles carrying a positive (cation) or negative (anion) electric charges

– Cations – carrying a positive electric charge• Na+, K+ , Ca2+, H+

– Anions – carrying negative electric charge• Cl-, HCO3

- , PO43-

• Non-electrolytes - Uncharged • Proteins, urea, glucose, O2, CO2

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Electrolyte balance

• Electrolytes (charged minerals) in the fluids help distribute the fluids inside and outside the cells, thus ensuring the appropriate water balance and acid-base balance to support all life processes.

• Excessive losses of fluids and electrolytes disturb these balances, and the kidneys play a key role in restoring homeostasis.

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• In all electrolyte solutions, anion and cation concentrations are balanced (the number of negative and positive charges are equal).

• If an anion enters the fluid, a cation must accompany it or another anion must leave so that electrical neutrality will be maintained.

• Thus, whenever sodium (Na+) ions leave a cell, potassium (K+) ions enter, moving, opposite directions.

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Minerals with special functions;Macro-minerals

metabolic role of sodium, potassium & chloride

• Important role in;• -electrical neutrality• -osmotic pressure• -acid-base balance• Na˖ is the major cation of extracellular fluids• K is intracellular fluids⁻• Cl is the major anion in extracellular fluid⁻

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• *Sodium is an Extracellular cation (Na+) (about 90%), functions in the regulation of ATP-dependent channels with potassium. These channels are referred to as Na+/K+-ATPases and their primary function is in the transmission of nerve impulses in the brain.

• Level in blood controlled by aldosterone, ANP, and ADH.

• 1-In the case of sodium, excessive sodium can cause hypernatraemia,

• and low sodium levels can cause hyponatraemia

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• *Potassium (K+) is major intracellular cation• Almost the presence of (K+) found in the cells• About 2% found in extracellular fluid• a key circulating electrolyte • involved in the regulation of ATP-dependent channels

along with sodium. • These channels are referred to as Na+/K+-ATPases• Na+/K+ Adenosine triphosphate pump actively

transports Na+ out of the cells and K+ into the cells in a 3:2 ratio to maintain the difference in Potassium content between ECF and ICF

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• Potassium maintain the intracellular;- • -osmotic pressure• -water balance• -acid-base balance• -Cofactor for several glycolytic enzymes• -transmission of nerve impulses• -activity and synthesis of nuclear and protein

depend of the presence of potassium

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• Potassium level in the plasma may cause;• 1-hyperkalameia; increase serum K in the

plasma

• 2-hypokalameia; decrease serum level in the plasma

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• Chlorine (Cl ) present as chloride ion. It is ⁻the major anion in the extracellular fluid

• Main function;• -regulate water balance (osmotic pressure and

acid base) as it is the part of NaCl• -nerve impulse conduction• -hydrochloric acid formation in the stomach

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• Plasma level of chloride change might cause;• abnormal metabolism of Na+ & Cl that might ⁻

lead to;-• 1-hyperchloraemia• 2-hypochloremia

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Macro-mineralsmetabolic role of calcium, phosphorous &

magnesium • Calcium, phosphorus and magnesium for cell metabolism, and

as structural units (bone and teeth)• Calcium (Ca++) a common electrolyte carrying positive

electrical charge (cation).• Calcium present in intracellular and extracellular fluid

• About 99% of body calcium is in the bone, the rest in the ECF.

• Nearly 50% of body calcium is ionized (free), whereas the remainder is complexes to albumin(40%) and anions such phosphate (10%)

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• Function of intracellular calcium;• -muscle contraction• -release of hormones (neurotransmitter &

neuromodulators• -activation of some enzyme• -Inter in glycogen metabolism• -cell division

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• Function of extracellular calcium• -maintain extracellular fluid calcium

concentration• -bone mineralization• -blood coagulation• -membrane excitability• -muscle contraction

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• Phosphorous• Phosphorous is required in the synthesis of nucleic acids

and high-energy compounds such as ATP.• It is also important in the maintenance of pH balance. • Act as part of a major buffer system (phosphoric acid and

its salts).• Phosphorus is also part of DNA and RNA and is therefore

necessary for all growth.• Many enzymes and the B vitamins become active only

when a phosphate group is attached. • The high-energy compound ATP uses three phosphate

groups to do its work.

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• Lipids containing phosphorus as part of their structures (phospholipids) help to transport other lipids in the blood.

• Phospholipids are also the major structural components of cell membranes, where they control the transport of nutrients into and out of the cells.

• Some proteins, such as the casein in milk, contain phosphorus as part of their structures (phosphoproteins

• parathyroid hormone (PTH) regulate phosphorous balance.

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• Magnesium (Mg++) : a cation within the body’s cells, active in many enzyme systems

• More than half of the body’s magnesium is in the bones.

• Much of the rest is in the muscles and soft tissues, with only 1 percent in the extracellular fluid.

• As with calcium, bone magnesium may serve as a reservoir to ensure normal blood concentrations.

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• Magnesium is necessary for energy metabolism. It participates in hundreds of enzyme systems.

• A major role of magnesium is as a catalyst in the reaction that adds the last phosphate to the high-energy compound ATP, making it essential to the body’s use of glucose;

• Involved in the synthesis of protein, fat, and nucleic acids; and the cells’ membrane transport systems.

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• Together with calcium, magnesium is involved in muscle contraction and blood clotting: calcium promotes the processes, whereas magnesium inhibits them.

• This dynamic interaction between the two minerals helps regulate blood pressure and lung function.

• supports the normal functioning of the immune system

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• Aldosterone controls magnesium concentrations in the extracellular fluid.

• Low Mg++ levels result in an increased aldosterone secretion, and the aldosterone increases Mg++ reabsorption by the kidneys

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Minerals with special functions;Micro-minerals

metabolic role of cobalt Co, copper Cu, fluorine F, iodine I2, iron Fe, manganese Mn, chromium Cr, zinc Zn, selenium Se

• cobalt (Co); central in corrin ring of vitamin B12

• Deficiency result in pernicious anemia of vitamin B12

• Revision of vitamin cyanocoblamin B12 is required

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• Chromium (Cr) needed in small amount which is essential for certain biological function such as;-

• -control of glucose and lipid metabolism• -as cofactor for insulin in increasing glucose

utilization and transport of amino acids into cells

• -lower cholesterol level

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• Manganese (Mn) is involved in reactions of protein and fat metabolism, promotes a healthy nervous system, necessary for digestive function, bone growth, and immune function. In addition, manganese is necessary for the proper function of super oxide dismutase (SOD) which is an enzyme required for preventing super oxide anions from damaging cells.

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• Copper (Cu) is involved in the formation of red bloods cells, the synthesis of hemoglobin

• Involve in oxidation reduction reactionsas it is an integral comonent of many metalloenzume includingcytochrome oxidase, superoxide dimutase, tryptophan dioxygenase, ferroxidase-

• iron absorption through ferroxidase that oxidize ferrous ion to ferric ion.

• Copper is also involved in the proper processing of collagen (the most abundant protein in the body) and thus, is important in skin, bone, and connective tissue production.

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• Iodine (I2) is required for the synthesis of the thyroid hormones (triiodothyronine T3 and tetraiodothyronine T4)

• Deficiency leads to cretinism in children and goiter in adult

• Cretinism;- deficiency during pregnancy lead to neonatal hypothyrodism which result in cretinism in children characterized by mental retardation, dwarfism, retarded development

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• Goiter characterized by enlargement of thyroid gland, and impairment of thyroxin production

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• Iron (Fe), synthesis of haem compound such as haemoglobin, myoglobin, chytochromes, catalase and peroxidase

• stored in the body as ferritin or haemosiderin• Ferritin is the main iron storage compound

(liver, spleen and bone)• The protein compound of ferritin is apoferritin• Deficiency lead to low heamoglobin resulting

in;-hypochromic microcytic anaemia

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• Selenium (Se) constituent of glutathione peroxidase which has antioxidant function

• antioxidant protects the cell membrane against oxidative damage by H2O2

• This function is important in preventing lipid oxidation and protect cell against superoxide free radicals

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• Zinc (Zn) is found as a co-factor in over 300 different enzymes and thus is involved in a wide variety of biochemical processes.

• Zinc interacts with the hormone insulin to ensure proper function and thus this trace mineral has an important role in regulation of blood glucose levels via insulin action.

• Zinc also promotes wound healing, regulates immune function, serves as a co-factor for numerous antioxidant enzymes, and is necessary for protein synthesis and the processing of collagen

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sulfur for three essential amino acids and therefore many proteins (skin, hair, nails, liver, and pancreas) • Sulfur has a primary function in amino acid

metabolism but is also necessary for the modification of complex carbohydrates present in proteins and lipids, however, it should be noted that in this latter function the sulfur comes from the amino acid methionine.

• Function as cofactors or regulators of enzyme function

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• http://wiki.answers.com/Q/What_is_dehydration_synthesis#ixzz2BuiK645Y