THROXINE (T4) AND TRIIODOTHYRONINE (T3) Presentation by: Sofia Vitale Francesca Canepa Alexandra Aguero Sarah Morin

WHERE IS THE HORMONE PRODUCED? Thyroid hormone is a metabolic hormone secreted by the thyroid gland. There are two types of thyroid hormones, thyroxine (T4), and triiodothyronine (T3).

WHAT ARE THE TARGET ORGANS/STRUCTURES OF T3 AND T4? T3 and T4 affect every cell and all the organs of the body. Too much of either of these speeds things up and too little of these slows things down.

HOW IS THE SECRETION OF THE HORMONE REGULATED/CONTROLLED? Too much of TSH result in increased thyroid hormone synthesis and release into the blood stream, and too little of TSH result in decreased synthesis and that releases into the blood stream. The amount of TSH secreted is controlled by the thyroid-releasing hormone, which is produced by an organ called the hypothalamus. When the amount of thyroid hormones in the blood reaches a certain level, the hypothalamus stops secreting thyroid-releasing hormone. This stops the secretion of TSH, which stops the secretion of T3 and T4.

WHAT IS THE NORMAL FUNCTION OF THE HORMONE? The function for both T4 and T3 would be to regulate Metabolism. The hormone are basically are specialized substances that coordinate the activities of specific cells in certain areas of the body. The hormone are produced by cells in glands, which they’re secreted by the gland into the bloodstream. After that, the bloodstream then transports the hormone to certain tissues, where the hormone has its effect.

HOW DOES THE HORMONE CONTRIBUTE TO HOMEOSTASIS? The hormone alter the metabolism of target organs by increasing or decreasing their activity. Changes in activity are strictly balanced to maintain homeostasis.

WHAT ARE THE CAUSES AND SYMPTOMS OF HYPOSECRETION OF THE HORMONE (OR RECEPTOR BLOCKAGE)? Hyposecretion of ADH is called the syndrome of inappropriate antidiuretic hormone. This can cause the symptoms retention of fluid, headache, disorientation, weight gain and also blood concentration goes down. Hyposecretion of ADH is diabetes insipidus, which can cause an increase in urine output and excessive thirst.

WHAT ARE THE TREATMENTS FOR UNDER OR OVER ACTIVATION OF THE HORMONE PATHWAY Hypersecretion are used to treat the underlying causes when possible, monitor fluid intake, and for very symptomatic patients, get hypertonic saline. Hyposecretion are treated with a synthetic hormone called desmopressin.

HOW, IF AT ALL, IS THE HORMONE USED CLINICAL OR COMMERCIALLY ADH is neither used clinically or commercially. ADH is actually a naturally produced hormone.

RESOURCES     ormone.htm ormone.htm  hormones-in-living-creatures.html hormones-in-living-creatures.html