Retired Army Major Michelle Dyarman holds the Purple Heart medal she was awarded after suffering a severe concussion from an IED in Baghdad in 2005. Robb Hill for NPR hide caption

itoggle caption Robb Hill for NPR

John Walker Lindh was captured in Afghanistan in 2002 after fighting with the Taliban. File Photo/AP hide caption

itoggle caption File Photo/AP

A training session for instructors who teach hand-to-hand combat, or combatives, at the Fort Benning military base in Georgia. Pouya Dianat for NPR hide caption

itoggle caption Pouya Dianat for NPR

Organ and tissue donation forms vary from state to state. Some are very general, while others allow people to choose or restrict what they want to donate. iStockphoto.com hide caption

itoggle caption iStockphoto.com

Unlike organs, tissue doesn't need to be transplanted immediately. Storage facilities like Tissue Banks International in San Rafael, Calif., process and store donated tissue for later use in medical products or as transplants. Noah Berger/AP hide caption

itoggle caption Noah Berger/AP

Chris Truitt holds a photo of his daughter, Alyssa, who died when she was 2, at his home in De Forest Wis. After donating her organs and tissues, he decided on a career change that made him rethink tissue donation. Narayan Mahon for NPR hide caption

itoggle caption Narayan Mahon for NPR

Coal miner Lee Hipshire in 1976, shortly after emerging from a mine in Logan County, W.Va., at the end of his shift. A few years later, Lee took early retirement because of pneumoconiosis, or black lung disease. He died at 57. Courtesy of Earl Dotter hide caption

itoggle caption Courtesy of Earl Dotter

Coal miners are tested for black lung. Recently, the deadly disease has been discovered in younger miners and at more advanced stages. David Deal for NPR hide caption

itoggle caption David Deal for NPR

Coal miners are tested for black lung at a clinic in West Virginia. David Deal for NPR hide caption

itoggle caption David Deal for NPR