Q.Calcitonin, a hormone that lowers blood calcium level by inhibiting bone resorption, is secreted by the

Iodine is an essential raw material for thyroid hormone (thyroxine) synthesis; without enough dietary iodine the thyroid gland enlarges to compensate, causing goitre, which iodised salt prevents.

The thyroid gland uses iodine as a key building block to synthesise its hormones, thyroxine (T4) and tri-iodothyronine (T3), which regulate the body's basal metabolic rate, growth, and development. When dietary iodine intake is insufficient, the thyroid cannot make enough hormone. This low hormone level is sensed by the pituitary gland, which responds by secreting more thyroid-stimulating hormone (TSH) to try to push the thyroid to work harder. Under this constant TSH stimulation, the thyroid gland enlarges, a swelling visible in the neck known as goitre (specific …

Iodised salt supplies iodine for thyroxine synthesis; iodine deficiency causes the thyroid to enlarge (goitre), so iodised salt prevents it.

The thyroid gland uses iodine as a key raw material to synthesise the hormone thyroxine (T4), which regulates the body's basal metabolic rate.

When dietary iodine is insufficient, thyroxine production falls. The pituitary gland senses low thyroxine and secretes more TSH (thyroid-stimulating hormone) to compensate, which makes thyroid cells multiply and the gland swell — this enlargement of the thyroid is called goitre.

…

The thyroid gland, a bilobed structure in the neck, is the largest endocrine gland in the human body.

Endocrine glands are ductless glands that secrete hormones directly into the bloodstream. Among all the endocrine glands in the human body, the thyroid gland is the largest, weighing roughly 15-20 g in an adult. It lies in the neck, just below the larynx, with two lobes connected by a narrow isthmus lying across the trachea. It secretes the iodine-containing hormones thyroxine (T4) and triiodothyronine (T3), which regulate the body's basal metabolic rate, growth, and development, along with calcitonin, which helps regulate blood calcium. By comparison, the pineal gland is a tiny structure in the brain, the pituitary (though called the 'master glan …

Exophthalmic goitre (Graves' disease) is caused by hyperthyroidism (excess thyroxine), which is the OPPOSITE of the other three listed conditions, which all result from iodine/thyroxine deficiency.

Disorders related to the thyroid and iodine intake:

• Simple goitre (endemic goitre): enlargement of the thyroid gland due to iodine deficiency, causing reduced thyroxine synthesis, which triggers excess TSH and gland enlargement.
• Sporadic goitre: goitre occurring in areas without general iodine deficiency, still generally linked to inadequate thyroid hormone synthesis/deficiency-related causes.
• Myxedema: a hypothyroid condition in adults caused by low thyroxine, leading to swelling, low metabolism, and other symptoms. …

(a) Thyroxine — the thyroid hormone that sets/maintains the basal metabolic rate (BMR) of the body.

Thyroxine, from the thyroid gland, regulates BMR.

Thyroxine (T4, along with tri-iodothyronine T3) is secreted by the thyroid gland and is the principal hormone controlling the body's basal metabolic rate — it stimulates oxygen consumption and cellular metabolism (carbohydrate, protein and fat metabolism) in nearly all tissues. Too little thyroxine (hypothyroidism) lowers BMR, causing sluggishness and weight gain; too much (hyperthyroidism) raises BMR, causing symptoms like increa …