University of Utah
University of Utah: Cardiovascular Pathology Index
This site features a detailed index of photographs for cardiovascular pathology. You can see what a normal human heart looks like and what a sick one looks like too. Come and check it out.
Khan Academy
Khan Academy: Your Heart Does Work: A Relationship of Pressure and Volume
Read this passage and study the graph to complete the five-question quiz related to how the heart works including the relationship of pressure and volume.