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amyloidosis in p. 216
associations p. 729
carcinogens in p. 223
goiter p. 348
metastases to p. 224
Psammoma bodies in p. 225
Normally, the hypothalamus, which is located at the base of the brain, secretes thyrotropin-releasing hormone, or ΤRH, into the hypophyseal portal system - which is a network of capillaries linking the hypothalamus to the anterior pituitary.
The anterior pituitary then releases a hormone of its own, called thyroid-stimulating hormone, thyrotropin or simply TSH.
TSH stimulates the thyroid gland which is a gland located in the neck that looks like two thumbs hooked together in the shape of a “V”.
The entire gland is covered in a thin, tough membrane called the fibrous capsule.
If we zoom into the thyroid gland, we’ll find thousands of follicles, which are small hollow spheres whose walls are lined with follicular cells, and are separated by a small amount of connective tissue.
Follicular cells convert thyroglobulin, a protein found in follicles, into two iodine-containing hormones, triiodothyronine or T3, and thyroxine or T4.
Once released from the thyroid gland, these hormones enter the blood and bind to circulating plasma proteins.
Only a small amount of T3 and T4 will travel unbound in the blood, and these two hormones get picked up by nearly every cell in the body.
Once inside the cell T4 is mostly converted into T3, and it can exert its effect. T3 speeds up the basal metabolic rate.
T3 increases cardiac output, stimulates bone resorption - thinning out the bones, and activates the sympathetic nervous system, the part of the nervous system responsible for our ‘fight-or-flight’ response.
Thyroid cancer is a type of cancer that develops in the cells of the thyroid gland, specifically from follicular cells or C cells. There are three main types of thyroid cancer: differentiated, medullary, and anaplastic.
In differentiated thyroid cancer, the cancer arises from follicular cells, and it's known as differentiated because the cancer cells look and act like normal thyroid cells. Medullary carcinoma arise from the C-cells of the thyroid which produce calcitonin, whereas anaplastic carcinomas are named so because they have altered cells that don't look anything like normal thyroid cells. Symptoms of thyroid cancer can include a lump or swelling in the neck, pain in the neck or throat, difficulty swallowing or breathing, hoarseness, and a persistent cough. The treatment of thyroid cancer depends mostly on the type of cancer and how it has spread. Options
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