Welcome back! In this module we consider how the circulatory system works to deliver oxygen and nutrients to the specific organs. We start with a discussion of the electrical and mechanical functions of the heart which enable it to generate a pressure gradient. This pressure gradient propels the blood through the blood vessels, in a unidirectional manner. The following session considers the factors that govern delivery of gases and nutrients at the tissue level. The last session considers the entire reflex loop, its control, and its response to daily demands (rest and exercise) and how pathology affects these responses. This is a busy week! The things to do this week are to watch the 5 videos, to answer the in-video questions, to read the notes, and to complete the CV problem set. It will be most effective if you follow the sequence of videos. The notes provide a more detailed summary of each topic. We encourage you to find which resource (videos and/or notes) works best for you and to try the problems sets. The problem sets are not graded. Both your understanding and retention will increase with application of the new learned information.