You must first complete Pre-Course Welcome – ECC before viewing this Lesson
Please sign up for the course before starting the lesson.
Respiratory System The respiratory system is a sequence of organs which allow you to breathe. It consists of three main parts which are the airway, lungs and diaphragm. The room air (fresh air) we breathe in contains about 21% oxygen which is used by the lungs by removing the oxygen and passing it through our […]