Cross section of heart indicating heart valves
The four valves determine the pathway of blood flow (indicated by arrows) through the heart
This cross-section of the heart indicates the aorta, pulmonary artery, left and right pulmonary arteries, left and right pulmonary veins, left and right atria, mitral valve, left and right ventricle, septum, direction of blood flow, pulmonary valve, inferior vena cava, tricuspid valve, aortic valve, and superior vena cava.
Source
Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:
"Pediatric Cardiothoracic Surgery - Heart Valve Disease."
http://pediatricct.surgery.ucsf.edu/conditions--procedures/heart-valve-disease.aspx
University of California San Francisco
Public domain.