Positive and Negative Feedback Mechanisms - Essay Example

            In the study of endocrinology, negative feedback occurs each time a person experiences a sudden increase or decrease in the level of hormones. For example, given that there is a sudden decrease in the calcium homeostasis in the blood (<9-11mg/100ml), the parathyroid gland will secrete parathyroid hormone (PTH) to regulate the calcium ion (CA2+) in the blood. Basically, the PTH is responsible for the development of osteoclasts (a.k.a. the process of destructing the bone cells to release more calcium in the blood). On the other hand, given that there is excessive calcium in the blood (>9-11mg/100ml), the parathyroid gland will secrete calcitonin hormone to stimulate the calcium salt deposit in the bone (Marieb, 2004, p. 290). Thus, maintaining the balance of calcium levels in the blood.

            The process of accelerating blood clots is considered a positive feedback mechanism (Martini, 2007, p. 10; Marieb, 2004, p. 10). Based on scientific explanation, the process of blood clotting evolves in three major phases known as platelet plug formation, vascular spasms, and coagulation. As soon as the platelet plug forms, the platelet releases some chemicals to attract more platelets to pile up in the wounded area. Before a vascular spasm takes place, the platelet will release serotonin to make the vessels constrict. Eventually, coagulation takes place when the injured tissue releases thromboplastin (responsible for blood clotting) and PF3 (interacts with thromboplastin and other blood protein clotting factors to form clotting cascade) (Marieb, 2004, p. 316).