CLINICAL CHEMISTRY LECTURE 4 PDF

‫اكاديمية المواهب الطبية‬ CLINICAL CHEMISTRY ELECTROLYTES AND MINERALS (TRACE ELEMENTS) METABOLISM LECTURE 4 DESIGNED BY : MJ-M6 Electrolytes and Minerals (Trace Elements) Metabolism Minerals are inorganic substances mined from the earth. Minerals They are not of plant or animal origin. They exist n...

‫اكاديمية المواهب الطبية‬ CLINICAL CHEMISTRY ELECTROLYTES AND MINERALS (TRACE ELEMENTS) METABOLISM LECTURE 4 DESIGNED BY : MJ-M6 Electrolytes and Minerals (Trace Elements) Metabolism Minerals are inorganic substances mined from the earth. Minerals They are not of plant or animal origin. They exist naturally on and in the earth and many are critical Of the 92 naturally occurring elements, the 14 minerals that have been shown by research to be essential to human health are: Calcium chromium copper fluorine iodine iron magnesium 14 essential minerals manganese molybdenum phosphorus potassium selenium sodium and zinc. 1 Essential macro minerals are those needed in significant quantities (such as calcium) usually measured in milligrams Essential trace minerals are those needed in minute quantities (such as selenium) usually measured in micrograms (one microgram milligram [mg]). We have less than 100 years of knowledge on the role of elements in the human body. It is estimated that 98% of the body mass of the man is made up of nine nonmetallic elements. The four main electrolytes namely Sodium Magnesium Potassium And calcium constitute about 1.98 %, while the rest 0.02%, or 8 an average human adult adults are made up of 10 typical trace elements. However, this tiny fraction exerts a tremendous influence on all bodyfunctions. 2 Minerals are required for a variety of physiological functions, their functions are: Maintenance of osmotic pressure of the cell Transport of oxygen Growth and maintenance of tissues and bones Working of the nervous system Muscle contraction Maintenance of electrolytic balance Acid-base balance The major elements that compose the human body and their relative amounts are as follows: The mineral content of humans Percent Approximate amount Element body (in gm) in 70 Kg adult. milligram [mg]). Ca++ 1.50 1050 Fe++ 0.004 003 P 1.00 700 Na++ 0.15 105 Zn++ 0.0033 02 Cl 0.15 105 K+ 0.35 Mg++ 0.05 3 245 035 Quantity elements (electrolytes) Na (Sodium) Mg (Magnesium) K (Potassium) Ca (Calcium) P (Phosphorus) S (Sulfur) Cl (Chlorine). Essential trace elements Mn (Manganese) Fe (Iron) Co (Cobalt) Ni (Nickel) Cu(Copper) Zn (Zinc) Mo(Molybdenum) Se (Selenium) I (Iodine). Function suggested from active handling humans, but no specific identified biochemical functions Li (Lithium) V (Vanadium) Cr (Chromium) B (Boron) F (Fluorine) Si (Silicon) As (Arsenic). 4 Electrolytes (Na, K, Mg, Ca, Cl) Sodium (Na ++): Sodium is a major cation and contributor to the osmolality of the extracellular fluid of the body which is one-third of the body water in adults. The sodium content of natural food varies between 0.1 and 3.3 mmol/100 In contrast, processed foods have a sodium content of 11 48 mmol/100 g, partly sodium nitrate is used as a preservative. Sodium is concentrated in the extracellular fluid giving osmolarity and charge moves from the extracellular fluid into cells there is a change in charge and concentration. Absorption and availability of sodium Intestinal sodium absorption is very efficient in both the small intestine and colon. Sodium is absorbed by a variety of processes. In the proximal intestine sodium is absorbed in part by an absolute-dependent cotransport system and is involved in nutrient absorption. 5 In the more distal intestine and colon, sodium absorption is by a sodium/hydrogen interchange; in the colon, this process is coupled to chloride/bicarbonate exchange. In the distal intestine and colon, the process is electroneutral and involves protein carriers. In the distal colon active, sodium transport occurs against an electrochemical gradient. Water absorption is passive process requires the active transport of sodium and chloride. The optimum absorption of water occurs when the concentration of glucose in the intestinal lumen is around 110 mmol/l. This finding has been of great importance in the development of Oral Replacement Solutions (ORS). 6 Sodium regulation : Sodium is found in significant amounts in bone but this pool is not readily available at times of rapid loss of sodium. The extracellular fluid sodium content is regulated in parallel with the extracellular fluid volume control. When the extracellular fluid or blood volume falls sympathetic activity increases and the response comprises vasoconstriction a redistribution of renal blood flow reduced glomerular filtration and increased sodium and water retention. In addition, there are increases in renin production circulating angiotensin II noradrenaline adrenaline ACTH and ADH. 7 Sodium excretion : Sodium is filtered from the plasma in the kidneys, and the reabsorption of sodium occurs as an osmotic phenomenon in the proximal tubule loop of Henle and distal tubule. Distal tubular absorption is very important and is under the control of the trial natriuretic factor. Renal sodium excretion is controlled by angiotensin II Prostaglandins and the kallikrein-kinnikinic system. Sodium depletion : Sodium is lost largely via the urine with only minimal loss occurring via the feces or skin unless there are abnormal situations such as diarrhea or excessive sweating. A reduced body sodium pool results in reduced extracellular fluid volume. 8 Na Na Na Increased sodium loss in urine can occur in diseases, e.g., diabetes mellitus cortical insufficiency) following excessive doses of diuretic drugs and in cases of renal tubular damage, as in chronic renal failure. Healthy kidneys maintain a consistent level of sodium in the body by adjusting the amount excreted in the urine. When sodium consumption and loss are not in balance, the total amount of sodium in the body is affected. The concentration of sodium in the blood may be :- -Too high (hypernatremia) -Too low (hyponatremia) In Hypernatremia, the body contains too little water for the amount of sodium. The sodium levelin the blood becomes abnormally high when water loss exceeds sodium loss. Usually,hypernatremia results from dehydration. 9 For example, people may lose body fluids and become dehydrated due to: Drinking too little. Vomiting. Havig diarrhea Using diuretics. Sweating excessively. Insufficient water intake usually plays an important role. People with diabetes mellitus and high blood sugar levels may urinate in excessive amounts,causing dehydration. Dehydration can also be caused by kidney disorders and by diabetes insipidus which also causes people to urinate in excessive amounts although without high blood sugar levels and is due to inadequate or ineffective vasopressin secretion or action. 10