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The thyroid gland consists of two lobes; it is the largest (weighs about 25 grams) adult endocrine gland. The isthmus connects the two lobes of the thyroid gland. The thyroid is located at the neck, adjacent to the trachea, and beneath the larynx. It appears in a butterfly shape and is covered around the trachea. It is composed of thyroid follicles that are covered by follicular cells. The follicular cells secret thyroid hormones (TH) such as triiodothyronine (T3) and thyroxine (T4). The thyroid gland releases TH into the bloodstream. Thyroid hormones act by binding to their thyroid hormone receptors (TR), which is a superfamily of nuclear receptors. TR encoding genes are classified into α (TRα) and β (TRβ). Thyroid stimulating hormone (TSH) regulates hormones’ (T3 and T4) secretion from the thyroid. TH raises the
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A&P V.1(BIO 203)-W/CONNECT PKG
- A physician sees a patient whose symptoms include sluggishness, depression, and intolerance to cold. After eliminating other possible causes, the doctor diagnoses a hormone problem. What disorder fits the symptoms? Why does the doctor suspect that the underlying cause is a malfunction of the anterior pituitary gland?arrow_forwardAddisons disease develops when the adrenal cortex does not secrete enough mineralocorticoids and glucocorticoids. President John F. Kennedy was diagnosed with the disease when he was a young man. Before he started treatment with hormone replacement therapy, he was hypoglycemic and lost weight. Which missing hormone was responsible for his weight loss? How might Addisons disease have affected his blood pressure?arrow_forwardWhich hormones produced in the posterior and anterior lobes of the pituitary gland have the targets indicated? Below, fill in the blanks using the abbreviations noted in Section 15.3.arrow_forward
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