The Parathyroid Gland By Jonah Carleton Elise Voorhis
The Parathyroid Gland By Jonah Carleton, & Elise Voorhis
Overview ● ● ● Location ○ Four rice grain sized glands located on/behind the thyroid gland ○ Located in the center of the neck, at the back ■ Behind the thyroid gland ○ Top two are superior and bottom two are inferior Hormones Released ○ Parathyroid Hormone (PTH) ■ Function ● Stabilizes calcium and phosphorus levels ● PTH raises the level of calcium in the blood ○ Breaks down bone, causing the release of calcium ■ Not good for bones, but beneficial for other cells ○ Makes it easier for body to absorb calcium from food ○ Limits kidneys from excreting too much calcium ■ Calcium not lost in urine ■ Begins to produce calcitriol ● PTH decreases the level of phosphorus in the blood ○ Calcitriol ■ Helps the body absorb as much calcium as possible Regulated by Calcium Sensing Receptor (Ca. SR) ○ The Ca. SR senses changes in blood calcium levels and releases PTH accordingly Thyroid Gland Parathyroid Gland
The Parathyroid Gland Operates in a Negative Feedback Loop ● ● Feedback loop for calcitonin and parathyroid hormone ○ Calcitonin decreases blood calcium levels when they become too high ■ Calcitonin is produced in the thyroid gland, but it is involved in a loop with PTH ○ Parathyroid releases PTH when the blood calcium levels are too low ■ Signaled by the Calcium Sensing Receptor (Ca. SR) ■ Causes levels of calcium to increase ● Calcium taken out of the bones ■ Increased PTH activates the vitamin D system (calcitriol system) ● Calcitriol is “active vitamin D” ● Vitamin D is converted into calcediol in the liver ● This calcediol is then turned into calcitriol in the kidneys ○ This final transformation is regulated by PTH Parathyroid stops releasing PTH when the blood calcium levels are normal or too high ○ Calcium signals to Ca. SR which conveys message to the Parathyroid
Hyperthyroidism ● Disease where a parathyroid is overactive and produces too much PTH ○ Causes unusually high levels of calcium in the blood ■ Due to overactive parathyroid ○ Primary and Secondary forms ■ Both usually cannot be prevented ■ Vitamin D deficiency can lead to secondary hyperparathyroidism ○ Too much calcium gets taken out of bones ■ Weakens bones ○ Can be either 1, 2, 3, or all 4 of the glands being hyperactive ■ Very uncommon for 3 or 4 to by hyperactive (15 -10%) ○ Is more common as people get older ○ Women are twice as likely to develop hyperparathyroidism as men ○ Can be caused by overexposure of radiation ■ Most cases sporadic ■ 5% are inherited ○ Is treated by surgery ○ Enlargement of parathyroid gland called adenoma
Citations Campbell, Neil A. , et al. Campbell Biology in Focus. Pearson Education Limited, 2017. “Parathyroid Glands: Function. ” Function of the Parathyroid Glands, endocrinediseases. org/parathyroid_background. shtml. “Parathyroid Disorders. ” Medlineplus, U. S. National Library of Medicine, medlineplus. gov/parathyroiddisorders. html. Kleerekoper, Michael. “About the Parathyroid Glands. ” Empoweryourhealth, www. empoweryourhealth. org/endocrineconditions/parathyroid. “Parathyroid Gland Introduction. ” Parathyroid. com and Hyperparathyroidism, www. parathyroid. com/parathyroid. htm. Parathroid Gland - http: //www. thyroidutah. com/thyroid-conditions/parathyroid-disorders/ Enlarged Gland -https: //www. fairview. org/patient-education/40125 Feedback Loop- http: //slideplayer. com/slide/3722522/
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