iodine seminar (somya srivastava and smriti datta)

8/6/2019 Iodine Seminar (Somya Srivastava and Smriti Datta)

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We owe a great many thanks to a great many peoplewho helped and supported us during this seminar.

My deepest thanks to our lecturers, dr. Amrit pal KaurMam, Mr. Jai dev Singh sir and Mr. HimanshuKumar Sarathe sir.

We express our thanks to our dean dr. N.D.Shashikaran sir.

And lastly our families who supported us through and

through.

Thanking you.

Smriti Datta (79).

Somya Srivastava (80).B.D.S. Ist year.


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What are minerals?

Classification of minerals

Iodine Sources : rich, good and poor sources

RDA

Absorption, storage and transport

Plasma iodine Biochemical requirements

Biosynthesis of thyroid hormones

Deficiency disease

Toxicity


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A mineral is a naturally occurring solid

chemical substance that is formed through

geological processes and that has acharacteristic chemical composition, a highly

ordered atomic structure, and specific

physical properties

The study of minerals is called Mineralogy.


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Minerals

Principal Elements

Also called Macrominerals.

Required in amounts greater than 100 mg/day.

(Ca, P, Mg, Na, K, Cl, S)

Trace Elements

Also called Micro minerals.

Required in amounts less than 100 mg/day.

Essential Trace Elements

( Fe, Cu, I, Mn, Zn, Mo, Co, F, Se, Cr)

Possibly Essential Trace Elements

(Ni, V, Cd, Ba)

Non-Essential T race Elements

(Al, Pb, Hg, B, Ag, Bi)


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Iodine is an essential trace element.

The total body contains about 20mg iodine,

most of it (80%) being present in the thyroidgland.

Muscle, salivary glands and ovaries alsocontain some amount of iodine.

It is a bluish-black solid.

It is seen apparently sublimating at normaltemperature into a violet-pink gas that hasan irritating odour.


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Rich sources:

Seafood

Sea vegetables

Table salt


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Good sources:

Cod

Sea bass

Perch

Haddock


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Poor sources:

Dairy products


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RDA for In Micrograms Per Day

Infants 40

Children 60 - 110

Men 110 - 150

Women 80 - 115

Pregnant women 125

Lactating women 150


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Iodine as iodide is mainly absorbed from

small intestine.

Normally, about 30% of dietary iodine is

taken up by the intestinal cells.

Iodine absorption also occurs through skin

and lungs.


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About 80% of bodys iodine is stored in theorganic form as iodothyroglobulin (a

glycoprotein) in the thyroid gland. This protein contains thyroxine, diiodotyrosine

and triiodothyronine in different proportions.

Excretion of iodine mostly occurs through

kidney. It is also excreted through saliva, bile, skin,

and milk (in lactating women).


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The normal concentration of plasma iodine is4-10 mg/dl.

Most of this is present as protein boundiodine (PBI) and represents the iodinecontained in the circulating thyroidhormones.

PBI level decreases in hypothyroidism andincrease in hyperthyroidism.

RBC do not contain iodine.


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The only known function of iodine is itsrequirement for the syntesis of thyroid

hormones namely, thyroxine (T4) andtriiodothyronine (T3).

These hormones are involved in severalbiochemical functions.

Functionally, T3 is more active than T4. Stimulates metabolic activities and increases

oxygen consumption in most of the tissues ofthe body (except brain, lungs, testes and

retina).


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Uptake of iodide:

The uptake of iodide by the thyroid gland

occurs against a concentration gradient(about 20:1).

It is an energy requiring process and islinked to the ATPase dependent sodium-

potassium pump. Iodide uptake is primarily controlled by TSH.


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Antithyroid agents such as thiocynate andperchlorate inhibit iodide transport.

Formation of active iodide:

Thyroid is the only tissue that can oxidize I- toa higher valence state I+.

This reaction requires Hydrogen peroxide andis catalysed by the enzyme thyroperoxidase.


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NADPH dependent system supplieshydrogen peroxide.

TSH promotes the oxidation of iodide toactive iodine while the antithyroid drugs(thiourea, thiouracil, methinazole) inhibit.

Thyroglobulin and synthesis of T3 andT4:

Thyroglobulin contains about140 tyrosineresidues which can serve as substrates foriodine for the formation of thyroidhormones.


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Tyrosine (of thyroglobulin) is first iodinated at

position 3 to form monoiodotyrosine (MIT)

and then at position 5 to form diiodotyrosine(DIT).

Two molecules of DIT couple to form

thyroxine (T4).

One molecule of MIT, when coupled with one

molecule of DIT, triiodothyronine (T3) is

produced.


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GOITER: Any abnormal increase in the sizeof the thyroid gland is known as goiter.

Enlargement of thyroid gland is mostly tocompensate the decreased synthesis ofthyroid hormones and is associated withelevated TSH. Goiter is primarily due to a

failure in the auto regulation of T3 and T4synthesis. This may be caused by deficiencyor excess of iodine.


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SIMPLE ENDEMICGOITER: This is due toiodine deficiency in the diet. It is mostly found

in geographical regions away from sea coastwhere the water and soil are low in iodinecontent. Consumption of iodized salt isadvocated to overcome the problem of

endemic goiter. In certain casesadministration of thyroid hormone is alsoemployed.


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CRETINISM:Cretinism is a condition

associated with iodine deficiency and goiter,

commonly characterized by mentaldeficiency, deaf-mutism, squint, disorders of

stance and gait, stunted growth and

hypothyroidism.


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Excess iodide (more than 1.1 mg/day) hassymptoms similar to that in iodine deficiency.

Commonly encountered conditions areabnormal growth of thyroid gland anddisorders in the functioning of the organismas a whole.


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Biochemistry by U.Satyanarayan and U.

Chakrapani

Wikipedia

Internet


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iodine seminar (somya srivastava and smriti datta)

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