Community Medicine Lecture-6-

Learning objectives At the end of this lecture student would be able to : 1-Determine inorganic elements number & purposes. 2-Classify inorganic elements . 3-Determine essential facts about the macro-elements (Na , K). 4-Determine essential facts about the micro-elements (iodine , magnesium & iron) . 5-Identify clinical features & preventive measures of iodine deficiency . 6-Discuss mechanism of iron balance , types & preventive measures of iron deficiency anemia .

Inorganic Elements There are nineteen inorganic elements in the human body. All these elements are derived from food. Its main purposes are:- 1.It forms the main constituents of bones and teeth (calcium & phosphorous) . 2.It forms some constituents of body cells ,such as muscles, liver and blood cells. 3.It participate in the body fluids composition, such as sodium, potassium and chloride ions. It has stabilizing effect or function.

Classification Two main groups of inorganic elements . These are:- A. Macro-elements These are calcium , phosphorous , sodium , potassium chloride , sulfur and magnesium. B. Micro-elements These are iron, zinc, selenium, manganese, copper, iodine and cobalt. Other inorganic elements having yet a non well established function, including bromine, promethium , silver , barium , aluminum and gold.

All body fluids contain sodium chloride which is in its normal concentration (0.9%), is essential for normal life. Excessive loss of sodium chloride leads to Nacl depletion which results in muscle cramps. Sodium chloride usually lost through urine or sweat (excreted outside the body).

Through the process of acclimatization ,excessive vasodilatation of skin vessels will result in excessive sweating in order to increase the heat loss from the body. Nacl depletion can result into muscle cramps. Daily adults requirements is 3 grams.

Potassium Potassium has a similar chemical behavior to sodium , however it is found incorporated (not free) in the muscle cells and RBCs . Accordingly , only a little loss of potassium can occur through sweating . Apparent deficiency states occur in cases with repeated vomiting , sever persistent diarrhea and diuresis . Patient with potassium depletion usually presented Rich sources for potassium are meat , milk , cheese and fresh fruits juice .

Iodine It has a strong relation with thyroid gland function. Usually iodine is present in drinking water,sea fishes,shell fishes , and certain vegetables . Daily need is about 150-300 gm. 

Possible preventive measures for iodine deficiency :- Iodine deficiency can lead to :- 1.Goitre (thyroid enlargement) . 2.Malignancy . 3.Cretinism.Its incidence is 3% in endemic areas 4.Mutism –deafness . Possible preventive measures for iodine deficiency :- 1.Iodinization of salts. This method is the most cheep and practical. 2.Using oily iodine injections. Such method usually done in highly endemic regions .

Magnesium Magnesium deficiency can occur in starvation, repeated vomiting , intestinal fistulae , alcoholic mal-absorption , and long term use of diuretics . Common sources for magnesium are milk , cheese , nuts , meats , and legumes . Magnesium deficiency states can result in neuromuscular irritability , tremor , muscle cramps , confusion , hallucination , and reflex irritability .

Iron Human body iron is about 45 mg/Kg body weight. Its main function is oxygen transport and cellular oxidation. Human body iron is distributed in the following four main forms:- 1.Transport iron : 2.Haemoglobin It constitute most of the body iron (70%) .It is part of the heam portion of haemoglobin (RBC) . Also it is found in myoglobin of muscles (5%).

3.Storage iron in form of feritin 20% of body iron is stored in the liver , spleen and bone marrow. 4.Cellular tissue iron 5% of body iron is distributed through all cells as part of oxidative enzyme system for energy production.

Iron balance (absorption - transport -storage –excretion) The mechanisms of iron control lie in its absorption , transport and storage complex rather than its urinary excretion . A-Iron Absorption Only 10-30% of ingested iron in human diet is actually absorbed from the duodenum .

Iron usually enter the body in two main forms :- 1.Haem-form(iron containing non protein portion of hemoglobin) . It is of animal sources and usually absorbed rapidly . It presents about 40% of animal sources iron . 2.Non haem-form ( ). All plant sources iron and 60%of animal sources iron are included.

Apoferritin is the protein receptor in the intestinal mucosa (mostly in the duodenum). It receives iron to form ferritin . When all apoferritin is bound to iron , the extra amount of ingested iron will be eliminated in feces . Factors favoring iron absorption :- 1.Body needs In deficiency states or in periods of extra demand for iron e.g. in growing child or pregnancy, the mucosal ferritin will be lowered , thus more iron will be absorbed. 2.Acidity and reducing agents as vitamin C.

3.Calcium Adequate calcium intake will bind to and remove phosphate and phytate . Otherwise , these materials will bind with iron and inhibit its absorption.

Factors hindering iron absorption :- 1.Binding agents e.g. phosphate , phytate , tea and coffee. These agents will bind with iron and remove it from body. 2.Reduced gastric acid secretion e.g. in partial or subtotal gastrectomy .

B-Iron transport In the mucosal cells of the duodenum and proximal jejunum iron oxidized and bound with plasma transferrin for transport to body cells. Normally only about 20-35% of iron binding capacity of transferrin is filled .The remaining capacity forms an unsaturated plasma reserve for handling variances in iron intake.

C-Iron storage D-Iron excretion After being bound to plasma transferrin , iron is delivered to its storage sites in bone marrow and to some extent in liver . D-Iron excretion The main mechanism is at the site of absorption . Otherwise , only minute amount is excreted in urine and sweat.

Anemia's Anemia is a state of low hemoglobin concentration bellow normal level.  At the age of 6-12 years there is usually a slight increase in hemoglobin level to reach 14 gm in males and 13.7 gm in females . Later on, in males will continue to rise up to 15 gm when become 18 years and above while in females will decline to 12gm/100ml.

Iron deficiency anemia could be:- 95% of normal individuals show higher values .The geographical factors play here an important role specially high altitude. Iron deficiency anemia could be:- 1.Nutritional deficiency anaemia . It is a world wide nutritional problem. 2.Haemorrhagic origin anemia as in hookworm. It is more common among females during reproductive age and certain blood diseased individuals.

This occur in the presence of iron binding agents. 4.Malabsorption anaemia This occur in the presence of iron binding agents. Prevention of anaemia 1.Delay cutting of umbilical cord. 2.Iron and folic acid supplement to pregnant. 3.Addition of iron containing food to infant feeding after completing 3-4 months of age.

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