Homeostasis is most often accomplished thought

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Homeostasis is most often accomplished thought negative feedback Most common method the body has for maintaining homeostasis is the negative feedback Negative feedback is when the input and the output are opposites Ex: cold in the classroom >> input to the body is cold = shiver > which shivering produces heat; output is heat = return the body to normal temp by heating it More common than positive feedbacks in the human body o Homeostasis is anything but constant; if you are healthy, these internal conditions can only change so much with the external environment - Negative feedback o Involves returning internal conditions to a “set point” Ex: normal body temp is 98.6 o A negative feedback loops helps return internal conditions to a set point when they deviate too far outside of an acceptable range. The input and they output are opposites o EX: shivering when you get cold o Involves Sensors in the body to detect change and send information to the integrating center (usually the brain but not always) Integrating center assesses change around a set point. The integrating center than sends instructions to an effector Effector makes the appropriate adjustments o Ex: blood sugar >> high blood sugar (glucose) Regulated variable: any internal condition that must be monitored and maintained within the system Set point = “normal” blood glucose level Beta cells in pancreas release insulin which lowers blood sugar when blood sugar is too high o EX: fever is caused by immune system; normally shiver when you have fever; brain changes set point from 98.6 to 102 to be “normal” but doesn’t inform tissues; sensors in skin think “normal” is 98.6 instead of 102 so your tissues think that you are cold and this is why you get the chills when having a fever; fever is your body fighting infection; don’t take Tylenol to lower fever…just go to sleep - “Normal” glucose levels? o Set points aren’t set in stone o Can change depending on physiological state/activity, for example, right after eating vd. Right before eating o “normal” is a relative term and indicates an acceptable range; when you eat or don’t eat, this means that your level shouldn’t be below or above a certain number o When you eat, glucose levels are high; when you don’t eat, glucose levels are low o Average levels or normal levels are an indicator on how healthy one is; it is just a good starting point
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3 - Antagonistic Effectors o Homeostasis is often maintained by opposing effectors that move conditions in opposite directions This maintains conditions within a certain normal range or dynamic constancy When you are hot, you sweat; when you are cold, you shiver. These are antagonistic reactions - Feedback Control o Your body always needs energy but you aren’t always initiating it - Why do people often shiver when they have a fever?
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