Thyroid-Stimulating Hormone (TSH) By: Kajal GroverJayasri VijayNeal Shah

What is TSH?Thyroid-Stimulating Hormone (TSH or thyrotropin)Stimulates thyroid gland to produce Triidotheronine (T3) and Thyroxine (T4), which in turn stimulates oxidative respiration

How is TSH created?Hypothalamus produces Thyrotropin-Releasing Hormone (TRH)Triggers the anterior pituitary gland to release TSH (Thyroid-Stimulating Hormone)

Hypothalamus and Pituitary Glands

Thyroid Gland

General Overview of Glands

TSH = Peptide-Based

OverviewTSH (which is released from the pituitary gland) binds to the TSH receptor on the thyroid cells, activating adenylyl cyclase and cAMP. This stimulates thyroid growth and causes synthesis and the release of thyroid hormones T3 and T4 which stimulates our metabolic rates and are crucial for normal growth and development.

TSH Signaling Pathway

TSH Signaling Pathway

Negative FeedbackT3 and T4 concentrations in blood decreaseHypothalamus secrets TRH, stimulating TSH secretion from pituitary, which stimulates thyroid gland to release thyroxineThyroxine acts on hypothalamus and anterior pituitary gland to inhibit TRH and TSH secretionAllows homeostasis: keeps thyroxine levels fairly constant to control bodys metabolism

Negative Feedback Loop Diagram

Negative Feedback Loop Diagram

Negative Feedback ExampleExample of person lacking iodine in diet:Thyroid gland cant produce thyroxine (which contains 4 iodines per molecule)Thyroxine concentration in blood decreasesReduced inhibition received by hypothalamus and anterior pituitary glandCauses elevated secretion of TRH and TSHHigh levels of TSH stimulates thyroid gland, which swells with products of thyroxine metabolic pathwayStill cant produce thyroxine without iodineConsequence: enlarged thyroid gland (goiter)

TSH ReceptorToo much TSH binding to the TSH receptor on the thyroid cells will lead to hyperthyroid diseasesToo little TSH binding to these thyroid cells will lead to hypothyroid diseases

DiseasesHigh TSH HYPERTHYROIDISMHair loss, coarse texture of the hair, core body temperature increases, sweating, heart beats faster , oily skin, diarrhea , slows down mental developmentGraves Disease: goiter, nervousness, heat sensitivity, hand tremors, weight loss, fatigue

Goiter

DiseasesLow TSH HypothyroidismWeight gain, faster aging, lower core body temperature, tiredness , hair loss, dry skin, dry constipations, heart beats slower, memory impairment, blood pressure can dropMyxedema (swelling) of the legs in adultsCretinism in children: stunted growth and severe mental retardation

Myxedema in Legs

Diseases

How Pathway is Disrupted

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