Oxygen is essential for life. It is absorbed by the lungs and transported by haemoglobin within the erythrocytes to the tissues.

Within the individual cell it is involved in the production of adenosine triphosphate(ATP), a compound that stores chemical energy for muscle cells, by the oxidative metabolism of fats and carbohydrates.

Hypoxia causes anaerobic metabolism with a resulting build-up in Lactic acid, the result of muscle cell activity. If severe enough, the lack of ATP causes a breakdown in cellular function and the death of the individual.

Indications for oxygen therapy include high altitude, heart failure, anaemia, pulmonary hypertension, carbon monoxide poisoning, anaesthesia and post-operative recovery.

Carbon forms an essential part in all compounds found in living tissues.

Two isotopes of carbon, C11 and C14, are used in medicine.

Carbon-11 is used in positron-emission tomography(PET).

Carbon-14 is used as a tracer element in studying various aspects of metabolism.

It is the most abundant mineral in human body.

Calcium is essential for cell function, muscle contraction, the transmission of nerve impulses, and blood clotting. Calcium is especially needed by the growing child and the pregnant and nursing mother.  The uptake of calcium by the baby is helped by vitamin D.

Chief sources of calcium are dairy products, eggs, and green, leafy vegetables.

Hypocalcaemia:  Tetany - Clinical neurological syndrome characterized by muscular twitching and cramps and (when severe) seizures.

Hypercalcaeima: Calculi(stones) in the kidneys or gallbladder.

Recommended daily intake:

• 500 mg for children.
• 700 mg for adolescents.
• 500–900 mg for adults and
• 1,200 mg for pregnant or nursing mothers.

Medicinal preparations:

Calcium carbonate(chalk)

Calcium chloride - used as dehydrating agent.

Calcium gluconate - used to prepare calcium injections.

Calcium hydroxide(slaked lime)

Liquor of calcium hydroxide (lime-water)

Calcium lactate - used as supplementary calcium.

Calcium phosphate

Magnesium is essential for formation of bones and teeth, muscle contraction, nerve impulse transmission, and activation of many enzymes.  The adult body contains around 25 grams of magnesium, the greater part of which is in the bones.

Dietary sources include cereals, nuts, soya beans, milk, and fish. More than two-thirds of our daily supply comes from cereals and vegetables.

Deficiency leads to muscular weakness and interferes with the efficient working of the heart.

Medicinal preparations:

Magnesium carbonate and Magnesium trisilicate - Used to make Antacids.

Sulphate of magnesium(Epsom salts) - Used as purgative.

Phosphorus in combination with calcium forms the bones and teeth. It is also essential for formation of Phospholipids and nucleic acids.

Some phosphorus-containing compounds such as adenosine triphosphate(ATP) and Creatine phosphate are essential participants in the conversion and storage of energy.

Dietary sources include cereals, dairy products, and meat.

Maintains the normal heart rhythm, regulate the body’s water balance, conduct nerve impulses, and contract muscles.

Deficiency causes nervous disorders and poor muscle coordination.

Dietary sources of potassium include lean meat, whole grains, green leafy vegetables, beans, and various fruits, such as bananas, apricots, dates, and peaches.

Hypokalaemia:

Cause: loss of fluids through diarrhoea and/or vomiting.

Effects: fatigue, drowsiness, dizziness, and muscle weakness. In more severe cases, there may be abnormal heart rhythms and muscle paralysis.

Hyperkalaemia:

Cause: excessive intake of potassium supplements, severe kidney failure, Addison’s disease, or prolonged treatment with potassium-sparing diuretics.

Effects:  numbness and tingling, disturbances of the heart rhythm, and muscle paralysis. In severe cases, there may be heart failure.

Sodium helps to regulate the body’s water balance through osmotic pressure and maintain normal heart rhythm and is involved in conduction of nerve impulses and contraction of muscles.

The level of sodium in the blood is controlled by the kidneys, which eliminate any excess in the urine.

Deficiency is caused due to excessive loss of the mineral through persistent diarrhoea or vomiting, or profuse sweating. Symptoms include weakness, dizziness, and muscle cramps. In severe cases, there may be a drop in blood pressure, leading to confusion, fainting, and palpitations. Treatment is with supplements. In hot climates, sodium supplements may help to prevent heat disorders by compensating for sodium lost through heavy sweating.

Excessive sodium intake is thought to be a contributory factor in hypertension. Another adverse effect is fluid retention, which, in severe cases, may cause dizziness and swelling of the legs.

Medicinal preparations:

Sodium bicarbonate(baking soda) - used as an antacid in relieving indigestion associated with increased acidity of the gastric secretion.

Sodium citrate and Sodium acetate: used as diuretics.

Sulphur is an essential constituent of vitamin B1 and several essential amino acids.

It is necessary for manufacture of collagen and is a constituent of keratin.

Copper forms an essential part of several enzymes.

Excess of copper results in a rare inherited disorder called Wilson’s disease. There is no evidence of dietary deficiency of copper in humans.

Recommended daily intake:

Adult - 2 mg.

Medicinal preparations:

Copper sulphate(blue stone) - in small doses acts as a powerful astringent and in larger doses  acts as an irritant.

Nitrates of copper -  used as topical application on unhealthy ulcers and growths to stimulate the granulation tissue to heal rapidly.

In the form of fluoride it is one of the constituents of bone and teeth. Daily intake of fluorine prevents dental caries and also aids to reduce the acid-producing ability of microorganisms in plaque. It is also applied directly to the teeth as part of dental treatment or used in the form of mouthwashes or toothpastes.

Ingestion of excess fluoride during tooth formation can lead to fluorosis.

Iodine is essential to synthesise thyroid hormones(thyroxine).

Iodine has a highly irritating action and, when applied to the skin, stains the latter dark brown and causes it to peel off in flakes, while internally it is a violent irritant poison in large doses.

Due to antiseptic properties Iodine is used to sterilize the unbroken skin before an operation.

Radioactive iodine is used for diagnosing and treating disease of the thyroid gland.

Iron is an essential constituent of the red blood corpuscles, in the form of haemoglobin(the oxygen-carrying pigment). It is also present in muscle as Myoglobin, and in certain respiratory pigments.

Iron is absorbed principally in the upper part of the small intestine and stored in the liver(to a lesser extent in the spleen and kidneys), for use in the bone marrow to form haemoglobin in red blood corpuscles.

Recommended daily intake:

Adults - 15–20 milligrams. Requirement is high in during pregnancy.

Medicinal uses:

Treatment of iron-deficiency anaemias. Iron supplements may cause nausea, abdominal pain, constipation, or diarrhoea and may colour the faeces black.

Dietary sources include liver, cereals, fish, green leafy vegetables, nuts, and beans.

Iron deficiency anaemia:

Cause: abnormal blood loss, such as from a peptic ulcer or heavy periods and improper diet.

Haemochromatosis:

Cause: excessive iron in the tissues

Effects: Cirrhosis.

Zinc is essential for essential for normal growth, the development of the reproductive organs, normal functioning of the prostate gland, healing of wounds, and the manufacture of proteins and

nucleic acids in the body.

Dietary sources: lean meat, wholemeal breads, whole grain cereals, dried beans, and seafood.

Deficiencies:

Deficiency of zinc results in lack of growth, slow sexual development and anaemia.

Deficiency is also associated with a skin disorder known as acrodermatitis enteropathica.

In children, zinc deficiency impairs growth and delays sexual development.

Prolonged excessive intake of zinc may interfere with the intestinal absorption of iron and copper, leading to a deficiency of these minerals.

Symptoms of deficiency include impairment of taste and loss of appetite; there may also be hair loss and inflammation of the skin, mouth, tongue, and eyelids.

Medicinal preparations:

Zinc chloride + Zinc sulphate - used as an astringent mouthwash.

Zinc sulphate - used in the form of eye-drops in the treatment of certain forms of conjunctivitis.

Zinc oxide is included in many preparations for treating skin and scalp disorders.

Zinc oxide, zinc stearate, and zinc carbonate are made up in dusting powders, in ointments, in paste bandages or suspended in water as lotions for the astringent action they exert upon abraded surfaces of the skin.

Zinc is a main ingredient in ointment preparations used in treating ringworm.