in this lecture we're going to talk about homeostasis and all of the mechanisms that help the body maintain homeostasis homeostasis is the process of maintaining a stable internal environment there are three parts within the human body that help maintain homeostasis the first part is a receptor the second is the control center and the third is an effector using the illustration let's take a look at how homeostasis is maintained a variable is a condition that can be changed or regulated such as temperature if you notice the variable is on a level board this level board represents ideal normal values called a set point any changes away from the set point is called a deviation or an imbalance so when a deviation occurs and a variable is no longer in homeostasis the body will activate mechanisms that will oppose the deviation to to return the body back to homeostasis so let's take a closer look at homeostasis in action first a stimulus produces change in the variable causing an imbalance second a receptor detects the change third the receptor sends information to the control center fourth the control center sends signals to activate an affector and finally the response by the effector counters the imbalance produced by the initial stimulus to return the variable back to homeostasis there are two mechanisms which help maintain homeostasis the first mechanism is a negative feedback mechanism the second is a positive feedback mechanism a negative feedback mechanism is a mechanism that opposes a deviation from the set point it is the most common regulation mechanism to help maintain homeostasis below is the negative feedback mechanism for body temperature in this illustration 98.6 represents the set point a deviation occurs when the body temperature rises temperature receptors in the skin detect the rise in the temperature these temperature receptors then send the information to the hypothalamus in the brain next the brain sends signals to activate sweat glands which causes them to Bruce sweat which cools the body and lowers the body's temperature sweating opposes the initial rise in body temperature let's take a look what happen happens when the body gets cold so when body temperature decreases again temperature receptors in the skin detect the decrease in temperature these receptors send information to the hypothalamus in the brain the brain then sends signals to activate skeletal muscles the actions of the skeletal muscles will produce shivering which warms the body and raises the body's temperature shivering warms the body which opposes the initial decrease in body temperature and the last feedback mechanism that helps maintain homeostasis bis is positive feedback positive feedback mechanism is a mechanism that responds to the deviation by making the deviation greater positive feedback mechanisms are rare regulatory mechanisms child birth is an example of a positive feedback mechanism during childbirth the head of the baby pushes against the cervix nerve impulses from the cervix are transmitted to the brain then the brain stimulates the pituitary gland to secrete the hormone oxytocin oxytocin is carried by the bloodstream to the uterus oxytocin stimulates the uterus to contract which pushes the baby towards the cervix in essence the baby's head pushing against the cervix results in the uterus Contracting even harder