This course is the online version of BIOL 2501. BIOL 2509 is available to students prior to enrolment in Nursing, and current Nursing and BMLS students with permission of the instructor. This course is also available to other students (e.g., from Science) as an elective. The course introduces students to the study of the disruption of the normal balance of selected systems of the human body by disease and other perturbations.