Homeostasi

Notes

Homeostasis Homeostasis, from homoios meaning "same" and stasis meaning "state" or "standing," refers to maintaining a stable internal environment. It is the process by which the body keeps conditions such as temperature, water, ions, CO2, and glucose constant, even when external conditions change. •Negative feedback This is the primary mechanism that maintains stability. It involves three components: - Receptor: detects a change (e.g., temperature rises). - Coordinator (hypothalamus): processes the information. - Effector: produces a response to reverse the change (e.g., sweating to cool down). This process keeps the internal environment at a normal level. Example: body temperature regulation When it's cold: hairs stand up to trap air (goosebumps), little or no sweat is produced, and blood vessels constrict (vasoconstriction). When it's hot: sweating occurs, and evaporation cools the body; blood vessels widen (vasodilation) to release heat. •Positive feedback Unlike negative feedback, positive feedback amplifies the response rather than maintaining balance. Examples: - Childbirth: oxytocin causes contractions; the cervix dilates, releasing more oxy...