Khan Academy
Khan Academy: Infographic: Chemical Abundances: Human Body
Almost 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. View this downloadable infographic on the human body.
Other
Inside the Human Body: The Respiratory System
Information, activities, and games pertaining to the respiratory system, including more specific topics like lung health and wellness, air pollution, and tobacco.
OpenStax
Open Stax: Requirements for Human Life
Earth and its atmosphere have provided us with air to breathe, water to drink, and food to eat, but these are not the only requirements for survival. Although you may rarely think about it, you also cannot live outside of a certain range...
TED Talks
Ted: Ted Ed: How Breathing Works
This video describes how the process of breathing in the human body works. [5:19] Includes a brief quiz and a list of additional resources to explore.
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.