PSL301H1 Lecture Notes - Negative Feedback, Positive Feedback, Autocrine Signalling
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PSL301H1 Full Course Notes
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11:49 pm: physiology is the science of how the body functions, how systems work together - as one integrative system of the body, homeostasis is maintaining a constant and stable internal environment despite dynamic conditions. Negative feedback stabilize regulatory variables, while positive feedback o reinforces a positive stimuluse it needs something else to turn it off. Positive feedback [reinforcing: a good example of a negative feedback is the regulation of cortisol secretion. Hormone released from hypothalamus (crh) --> anterior pituitary reeleases o (acth) --> adrenal cortex releases (cortisol) o o. Elevatedcortisol shunts off the signal to cortisol secretion. Negative feedback action of cortisol suppresses crh & acth: a good example of positive feedback is the control of oxytocin and control of uterine contractions. Baby is ready to come, so it drops down lower in the uterus initiating labor --> o. Things can change, so not necessarily one set point: maintaining a homoeostasis and other body functions requires intercellular communication.
