The course "block" is required for all undergraduate 1st year medical students This block aims to introduce students to the human body’s internal environment, the potential hazards of external environment, protective mechanisms, and the body’s responses to keep Homeostasis. The students are expected to be armed with reasonable knowledge about environmental hazards, the potentialities of human adaptability on the cellular, tissue and organ levels to his environment, and the outstanding role of metabolism in homeostasis. The course components include the environmental interactions, both external environment and the internal environment, and the cellular response to the changing environmental stimuli. The role of nervous system in initiating the metabolism, the metabolic reactions and the pathways, and the changes that take place during environmental insults shall be dealt with. compensatory response will be discussed. The other component of the course is