All the body systems work together to insure the body has what it needs to conduct its life processes. Some of the systems work in a singular fashion, for example, the digestive systems job is to break food down into a form where the glucose and other nutrients may be absorbed for energy usage in the body. Other body systems serve multi-purpose roles, such as the endocrine system providing hormones promoting body growth, emergency energy production (adrenaline), and sex characteristics. All these systems work together to promote a process known as homeostasis, which is a fancy word that basically means "in balance". The nervous system works both directly and indirectly to promote this process of homeostasis. If the body overheats, due to illness or physical exercise, the sweat glands in the integumentary system release sweat, which evaporates, causing a cooling effect to cool the body down. The circulatory system serves as a body system "superhighway", getting nutrients and oxygen to all the cells and removing carbon dioxide and waste products. All in all, the human body is a complex system composed of organ systems that all work together to promote the bodys general welfare.