This course explores the fundamental principles of how the human body functions, from the cellular level to complex organ systems. Students will study mechanisms of homeostasis, energy balance, and communication through chemical, hormonal, and neural pathways. Emphasis is placed on the integration of major systems—circulatory, respiratory, digestive, nervous, endocrine, and others—to understand how they work together to sustain life. The course provides a foundation for medicine, health sciences, and comparative biology.