 Dear students, in this topic we shall discuss the feedback mechanisms and feedback loops. A feedback mechanism connects the response to the initial stimulus through a feedback loop or circuit. Feedback loops are characteristic of controlled pathways of hormones. Through these loops, secretion of hormone is regulated. The feedback loops may follow positive or negative pathways. The negative feedback loops are shown by the secretory activities of many hormones mostly involved in homeostasis. In negative feedback, the secretory activity is modulated by the negative feedback of the hormone itself or its byproducts. The hormone or any of its product tends to suppress its further release. This mechanism of negative feedback ensures a proper level of hormonal activity at the target tissue and prevents its overactivity. Dear students, the negative feedback may cause regulation of hormone at any level. For example, the synthesis of hormone may be stopped by controlling the gene transcription and translation steps. As a result, hormone synthesis will not occur. It may also be regulated at the level of activation of hormone, which may be blocked. The third level is that the hormone is active but its release is stopped or inhibited. So negative feedbacks can occur at all or any of these levels. Dear students, the negative feedback involves either a short loop or a long loop. In the short loop, hormone or its byproduct acts back directly on the secreting endocrine tissue, thereby inhibiting its own release. The long loop feedbacks also follow the same principle of negative feedback but here more than one endocrine gland and more than one hormone are involved. Dear students, now we shall discuss the positive feedback. In positive feedback, the secretion of hormone is directly or indirectly involved in increasing its own secretion. This positive feedback happens when an extremely rapid or strong action is required. Moreover, most hormonal pathways follow positive feedback during the initial stages of response. Dear students, let us take an example of positive feedback which is shown by the increased level of leutinizing hormone before ovulation. The level of leutinizing hormone increases due to the stimulatory effect of increased levels of astrogens on anterior pituitary. The positive feedback is ultimately countered by a negative feedback that ends with a negative feedback that ends the rapid increase. For example, when leutinizing hormone reaches a certain level, typical negative feedback control is exerted which lowers the leutinizing hormone and astrogen concentrations.