Negative Feedback Mechanism vs. Positive Feedback Mechanism - Med-Surg - Endocrine | @LevelUpRN

The video introduces the primary control mechanism for most hormones in the endocrine system: negative feedback. It also briefly touches on positive feedback, which controls a few specific hormones. A thermostat analogy is used to explain how negative feedback maintains set levels.

An endocrine gland senses if there's too much or too little of a circulating hormone. It then initiates changes to either decrease or increase hormone production to maintain homeostasis. This keeps hormone levels balanced, similar to how a thermostat regulates room temperature.

The production of thyroid hormones T3 and T4 is a specific example of negative feedback. The hypothalamus releases TRH, which stimulates the anterior pituitary to release TSH, which in turn causes the thyroid gland to produce T3 and T4. If T3/T4 levels are too high, the hypothalamus and anterior pituitary decrease their respective hormone production to reduce T3/T4. Conversely, if levels are too low, production increases to restore balance. Issues in any of these glands can disrupt this balance, leading to conditions like hypothyroidism or hyperthyroidism.

Unlike negative feedback where increased hormone levels lead to decreased production, positive feedback causes additional release of the same hormone. This mechanism controls only a few hormones.

Oxytocin is a hormone regulated by positive feedback. During childbirth, uterine contractions cause more oxytocin to be released, leading to stronger contractions. Similarly, during breastfeeding, the act of suckling causes oxytocin release, which triggers milk ejection, and this action further stimulates more oxytocin release. Oxytocin production ceases once the event (childbirth or breastfeeding) is over.