Mammals, like humans, are warm-blooded creatures that are able to maintain a relatively constant internal temperature regardless of the temperature of the surrounding environment. One example of homeostasis—an organism’s self-regulating process that tends to maintain internal stability while adjusting to conditions in ways that are best for survival—is the regulation of body temperature. Human body is a related subject. The human body’s ideal temperature is 37 °C (98.6 °F), but this can be affected by a number of things, such as exposure to the elements in the environment, hormones, a person’s metabolism, and disease, which can cause too high or too low body temperatures. Body temperature is regulated mainly by the hypothalamus in the brain. The nervous system and the circulatory system, whose pressure-sensitive receptors in the blood vessels collaborate with the nervous system to collect and communicate information on blood pressure, transmit temperature information to the brain. The brain adjusts the breathing rate, blood sugar levels, and metabolic rate to adjust for temperature changes. Perspiration, heat-exchange mechanisms that allow blood to circulate close to the surface of the skin, and a decrease in muscular activity all contribute to the promotion of heat loss. The body’s insulation mechanisms, such as reducing blood flow to the skin and the fat under the skin, as well as the use of clothing, shelter, and external heat sources, reduce heat loss. The hypothalamus controls the body’s shivering response, which can also generate heat. The range between high and low body temperatures constitutes the homeostatic plateau—the “normal” range that sustains life. The system returns to its normal range as either of the two extremes approaches through negative feedback.