Which system is primarily responsible for processing information and responding to internal and external changes?

The nervous system is primarily responsible for processing information and responding to both internal and external changes. This system consists of the brain, spinal cord, and a network of nerves that communicate signals throughout the body. It plays a crucial role in sensing external stimuli, such as light, sound, and touch, as well as internal conditions like temperature and pain.

Once the nervous system collects this information, it processes it and generates appropriate responses, often involving the activation of muscles or glands. This ability to interpret input and coordinate responses is vital for survival and adapting to various situations.

In contrast, other systems such as the muscular system focus on movement, the skeletal system provides structure and protection, and the cardiovascular system ensures the circulation of blood and nutrients. While these systems play supportive roles in the body's response to changes, they do not directly interpret sensory information or coordinate responses in the way that the nervous system does.