The human body is made up of several complex systems that work together to maintain balance and function. The nervous system processes information and controls responses to internal and external stimuli. The digestive system breaks down food and absorbs nutrients that fuel all bodily functions. The circulatory system moves blood, oxygen, and nutrients throughout the body, supporting every organ and tissue. The endocrine system is responsible for producing and regulating hormones, but each of these systems interacts closely to maintain health. Hormones act as messengers that influence growth, metabolism, mood, and many other processes. The body’s systems communicate constantly to adjust to changes in environment, activity level, and internal needs. Understanding how these systems work—independently and together—can help you appreciate the interconnected nature of your health and recognize how imbalances in one area may affect another.