Many systems work together to keep the body balanced, with the nervous and endocrine systems taking the lead. If the body becomes too hot, for example, part of the brain registers this and activates the sweat glands to help lower the temperature; when it’s too cold, the muscles are activated, shivering to help generate heat. If blood pressure falls, a specific neurotransmitter is released; this causes the blood vessels to constrict and increases the heart rate. This, in turn, causes blood pressure to rise. Other conditions in the body, like blood sugar levels and pH balance, are also monitored and adjusted when they fall outside the ideal range.