11 TED-Ed Videos on How the Human Body Works. Those videos are good introductions to a lot of topics in anatomy and physiology. For a more detailed look at topics in anatomy and physiology take a look at Crash Course A&P. The latest installment in the series is about the lymphatic system.
This Crash Course series is appropriate as review material for high school students who already have a fairly good understanding of anatomy and physiology.
These apps and sites are appropriate for younger students to learn about anatomy and physiology.