This course is an introduction to the human body systems and their physiology. Human body functions at the cellular, tissue, organ system, and organismal levels are included in the course. Topics include the scientific method, basic chemistry, cell structure and biochemistry, tissues, nervous integration and senses, the endocrine system, the cardiovascular system and blood, the lymphatic system and immunity, the respiratory system, the digestive system, the urinary system, and the reproductive systems and sexually transmitted infections. Students cannot receive credit for BIOL 2303 if BIOL 1404 or BIOL 1114 is concurrently or has been previously taken.