Engineers, particularly biomedical engineers, need to understand how our body systems work in order to help take care of our bodies on Earth and in space. The human body has many examples of joints, which engineers can mimic when designing machines. Specifically, in thinking about our skeleton while not on Earth, biomedical engineers who work at NASA are especially interested in how outer space affects astronauts' bones. And, aerospace engineers need to understand the immune system and how it is affected in space in order to prepare for longer missions (while astronauts are further away from the medical resources on Earth).
Furthermore, engineers continue to help protect the human heart by developing technological devices to repair it, such as artificial heart valves to replace faulty valves. Artificial hearts were developed by engineers to keep hospitalized patients alive while they are waiting for a heart transplant. What about our brains? Engineers develop better ways to save the brain from trauma and disease. They develop surgical and imaging equipment, as well as brain-saving devices, such as bicycle and motorcycle helmets. And for the visually impaired, engineers create sight devices from glasses to advanced sight tools (including a light sensor imbedded into the back of the eye) for people who cannot see at all or have difficulty seeing. Biomedical engineers create devices to aid people who have lost or are lacking full hearing capabilities. Engineers are also working on a drug that can keep astronauts from getting space-motion sickness, which is caused by conflicting sensory inputs.
Other life-saving measures are undertaken by chemical engineers, who study the immune system in order to develop treatments for people with compromised immunity, and vaccinations, antibiotics, disinfectants, and sterilizers are designed by engineers in order to help keep people healthy. Additionally, environmental engineers work on keeping the air we breathe and the water we drink free of toxins via air purifiers and water filters.
Clearly, engineers play a huge part in keeping the human body safe and healthy, both on Earth and in space.