This electronic textbook has been written especially for students of undergraduate courses Physical Education and Sport. The material used to extend the knowledge of physiology in the English laguage and thus to increase language skills. The following material contains up-to-date findings predominantly from the area of the physiology of exercise. It aims to gradually introduce its readers to individual functions of the organ systems playing a part in the movement activity. The material looks at various ways the organ systems in question, i.e. basic physiological parametres respond to the physical exercise. Given by the long-term perspective of physical training the publication also deals with emerging ways of workload adaptation. As movement activities may be carried out in extreme conditions, it also looks at an organism's response to heat, cold and the high altitude environment.