BIOL 030 Lecture Notes - Lecture 22: Homeostasis, Pancreatic Islets, Hyperglycemia
22 Dec 2020
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Document Summary
The thyroid is an important structure in maintaining metabolic homeostasis. The thyroid gland can be divided into the following anatomical structures: right lobe, left lobe, isthmus (between the lobes) The microscopic structure of the thyroid is composed of many structures called follicles. Each follicle is made up of simple cuboidal follicular cells. Dispersed between the follicles are the parafollicular or c" cells. Are simple cuboidal cells surrounding each follicle. These cells produce two thyroid hormones, triiodothyronine (t3) and thyroxine (t4), which act to increase the rate of metabolism and oxygen consumption. They produce calcitonin, a hormone which lowers blood calcium concentration. The parathyroid glands are four small oval glands on the posterior side of the thyroid. They are paired, with two superior glands and two inferior glands. Along with the thyroid, the parathyroid glands secrete hormones to contribute to calcium homeostasis. Pth acts to increase calcium ion concentration in the blood.
