Interrelationship of Body Systems

Why is the interdependence of body systems essential?

Homeostasis, or controlled internal conditions, is essential to an organism's survival. Wildebeest brain cells, like those of humans, must be kept at a stable temperature and supplied with a steady stream of glucose for energy—even when the animal is under stress. The brain cells must be bathed in fluid with a constant concentration of water and be cleansed of metabolic waste products. These conditions must not dramatically change during droughts, floods, famines, heat, or cold. Failure of homeostasis, even for a few minutes, would lead to permanent brain injury or death.

You've learned about digestive, respiratory, circulatory, excretory, nervous, muscular, and skeletal systems separately. Yet all of these systems are interconnected. All body systems work together to maintain homeostasis. In most animals, respiratory and digestive systems would be useless without circulatory systems to distribute oxygen and nutrients. Similarly, the excretory system needs a circulatory system to collect carbon dioxide and nitrogenous wastes from body tissues and deliver them to the lungs and excretory organs. Muscles wouldn't work without a nervous system to direct them and a skeletal system to support them.

In addition to the organ systems that you have already learned about, you will now learn about other body systems, those that fight disease, produce and release chemical controls, and manage body temperature—all to help ensure homeostasis.

FIGURE 28–26 Interrelationship of Body Systems All body systems must work together to keep stressed animals, such as these migrating wildebeests, alive.