Homeostasis AQA level with 100% correct answers

Homeostasis - relatively constant internal physical and chemical conditions that organisms maintain Negative feedback - A primary mechanism of homeostasis, whereby a change in a physiological variable that is being monitored triggers a response that counteracts the initial fluctuation. Positive feedback - Feedback that tends to magnify a process or increase its output. Normal blood glucose - 70-99mg/dl Glycogenesis - formation of glycogen from glucose Glycongenolysis - glycogen--> glucose (released into bloodstream) 1. controlled by glucagon Gluconeogenesis - formation of glucose from noncarbohydrate sources High blood glucose - Detected by beta cells. Insulin is secreted. Insulin travels in the blood to target cells. Causing adenyl cyclase to convert ATP into cAMP. cAMP activates enzyme controlled reactions to stimulate the opening of glucose channels in the cell surface membrane. Low blood glucose - Alpha cells detect a fall in blood glucose and secrete the hormone glucagon.