Tutoring biology, the concept of negative feedback is important to explain.\u00a0 Negative feedback is used by all\u00a0organisms to maintain their living state.\u00a0 You also use it while driving your car.<\/p>\n
More or less, the body needs all its processes to proceed at a constant, continuous rate.\u00a0 Change is the enemy for biological entities.\u00a0\u00a0However, as you interact with your surroundings – eating, exercising, and so on – change is imposed on your internal environment.\u00a0 Negative feedback<\/em> means that when a change happens, your body responds to negate that change – i.e., to bring\u00a0itself back to normal.\u00a0 Once\u00a0back to normal, your body stops its negative\u00a0response.\u00a0 It won’t respond again until another change brings it out of normal range.<\/p>\n Consider driving a car – specifically, steering.\u00a0 Imagine the road is straight, but your car starts drifting to the right.\u00a0 You correct by steering left, to bring the car back on course.\u00a0 In so doing, you are applying negative feedback.\u00a0 The car is going too far right, so you oppose that change of course by steering left.\u00a0 Once the car is back on course, you stop correcting:\u00a0 you let the wheel slide back to center.\u00a0 You won’t steer again until the car begins to drift off course once more.\u00a0 That process of opposite, corrective response is negative feedback<\/strong>.\u00a0 You can also call it a feedback loop<\/em>, since you base your reaction on what is already happening.<\/p>\n Biology has many examples of negative feedback, but we’ll look at the one involving the hormone thyroxin:<\/p>\n The hypothalamus – in the brain – monitors the body’s metabolism.\u00a0 If the metabolism gets too low, the hypothalamus stimulates the anterior pituitary.\u00a0 In response, the anterior pituitary\u00a0releases a hormone that causes the thyroid to release thyroxin.\u00a0 Thyroxin increases the body’s metabolism.<\/p>\n Once the metabolism\u00a0reaches an acceptable level, the hypothalamus stops stimulating the anterior pituitary.\u00a0 In turn, the anterior pituitary ceases to release the thyroid-stimulating-hormone.\u00a0 Therefore, the thyroid stops releasing thyroxin.\u00a0\u00a0The body’s metabolism remains constant – until another external change depresses it again.<\/p>\n Therefore, the connection among the hypothalamus, anterior pituitary, and thyroid gland constitutes a negative feedback system that maintains the body’s metabolism at a constant rate.\u00a0 This negative feedback system promotes homeostasis.\u00a0 Homeostasis<\/strong> means the maintenance of a constant internal environment.<\/p>\n