2. PARATHYROIDS By Afra Nehal and Nida Madni

3. LOCATION  Parathyroid glands are 4 small glands of the endocrine system which are embedded in posterior surface of the thyroid gland.

4. HORMONES THAT ARE PRODUCED The parathyroid glands release a hormone called parathyroid hormone (PTH). This hormone controls the levels of: calcium, phosphorus and magnesium. Parathyroid hormone has a number of effects in the body.

5. AFFECTS OF HORMONES ON BODY  It causes the release of calcium from bones.  It causes calcium to be absorbed (taken up into the blood) from the intestine.  It stops the kidneys from excreting (getting rid of) calcium in the urine.  It causes the kidneys to excrete phosphate in the urine.  It increases blood levels of magnesium.

6. HOMEOSTASIS  PTH has many effects on the bones and the kidneys.  It stimulates osteoblasts to pump Ca ++ ions out of the fluid. Over a longer time course, PTH stimulates bone reabsorption  Stimulates [Ca ++ ] on the kidney. First, it decreases the loss of Ca ++ ions in the urine by stimulating Ca ++ reabsorption. "Reabsorption" means the transfer of substances from the forming urine back into the ECF. Reabsorption, which is performed by the cells of the kidney tubules, allows the recovery of those useful small molecules such as sugars, amino acids, and Ca ++ ions. As well as stimulating Ca ++ reabsorption, PTH also inhibits phosphate reabsorption in the kidney.

7. EXAMPLES OF HORMONES

8. FEEDBACK MECHANISMS AND ANTAGONISTIC HORMONES  A negative feedback system involving 2 antagonistic hormones, calcitonin and parathyroid hormone (PTH), play the major roles in calcium (Ca2+) in order to maintain homeostasis in mammals.

9. RELEASING HORMONES AND GLANDS  Hormone Released: Parathyroid hormone (PTH)  Hormone Structure: Peptide  Hormone Function: Increases blood calcium concentrations by stimulating calcium release from bone, promoting calcium uptake from intestinal tract and decreasing calcium excretion by the kidney; Decreases blood phosphate level  Hormone Regulator: Calcium concentrations in blood

10. IMPROPER FUNCTION  Hyperparathyroidism occurs when the parathyroid hormone is produced by an overactive parathyroid gland. This is called hyperparathyroidism. Hyperparathyroidism occurs when one or four parathyroid glands grows into a tumor and behaves inappropriately by making excess parathyroid hormone which harms the body. Too much calcium in the bloodstream causes damage to the nervous system, and cause higher risk of cancer.

11. TREATMENTS  There are no pills nor drugs to cure this disease. The only way to solve/remove hyperparathyroidism is by having surgery.  The average operative time to remove the diseased parathyroid gland using this technique is about 25 minutes

12. PARATHYROID VIDEO  http://www.youtube.com/watch ?v=sD9st1ZPFrQ#t=302 http://www.youtube.com/watch ?v=sD9st1ZPFrQ#t=302

13. SOURCES  http://courses.washington.edu http://courses.washington.edu  www.parathyroid.com www.parathyroid.com  http://classes.biology.ucsd.edu http://classes.biology.ucsd.edu  http://faculty.clintoncc.suny.edu http://faculty.clintoncc.suny.edu