Last year, there were more than 100,000 Americans on the waitlist for a lifesaving organ transplant. Less than half received one.

"It's why checking the box to become organ donor is so important," says Dr. Constance Mobley, a transplant surgeon at Houston Methodist. "When you register as a donor, you're providing an opportunity to give life."

There are two ways organs are donated — through living donors and deceased donors.

The living donor program gives people the chance to give a kidney or portions of certain other organs — usually to a family member, loved one or friend; or by joining a transplant chain if the organ isn't a perfect match for the intended recipient.

"This happens very commonly for kidney transplants, where a person donates to someone they know," explains Dr. Mobley. "But living donations are much less common for other organs, like the liver. And a living donor can't donate certain vital organs, like their heart, of course."

Most crucial for such organs, notes Dr. Mobley, is the deceased donor program, which relies on people registering to donate in the event of their death.

What is an organ donor?

By registering as an organ donor, you're granting permission for your organs to be given to people in need should you pass away.

The major organs that can be donated after your death include your:

• Heart
• Kidneys
• Liver
• Lungs
• Pancreas
• Intestines

Organs or tissues you might not initially think about — like skin, corneas, bone, blood vessels and more — are also donated.

But Dr. Mobley notes that the decision to check the organ donor box is about much more than just the organs and tissues that get donated.

What does it mean to be an organ donor?

"You're doing more than giving an organ," says Dr. Mobley. "You're giving experiences back to people. Another birthday, another anniversary, another holiday, another hug — another moment they otherwise wouldn't have had. That's really what you're giving. That's what it means when you check that box."

As someone who sees the process firsthand, Dr. Mobley knows the powerful impact an organ donation brings. It's why she says being a transplant surgeon is the best job in the world.

"You meet these transplant patients when they are at their sickest — sometimes so critically ill you don't even get to speak to them, you only hear about them from their family members," says Dr. Mobley. "And with one gift from another family — in what is the darkest moment in their life — that gift is transformed into a miracle for that person and their family. The start of a new life."

How many lives can an organ donor save?

One organ donor can save eight lives, as well as enhance the lives of 75 other people through donated tissues, according to the Health Resources & Services Administration (HRSA), which is part of the U.S. Department of Health and Human Services.

"It's really more than this, though," adds Dr. Mobley. "You're touching people very directly by organ donation, but the ripple effect spreads through their entire family and network of loved ones and friends. It touches their spouses, their parents, their kids, their best friends. It's daughters getting to walk down the aisle with their dads, grandkids having their grandparents around."

Depending on the circumstances of a person's death, some organs or tissues typically procured for donation may not be fit for use.

"If the cause of death is a massive heart attack, you wouldn't be a candidate to donate a heart, for instance," says Dr. Mobley. "But you may still be a candidate to donate your kidneys."

And for those wondering whether their overall health or age might preclude their organs from being eligible for donation altogether, Dr. Mobley says you should still register.

"If your goal is to give life, register to be a donor," says Dr. Mobley. "The organ procurement team will figure the rest out should the time come. Even if your major organs can't be used, things like your corneas, skin, bone and other tissues can greatly improve someone's life."

Should you be an organ donor?

Despite the lives organ donation saves, some people may still feel hesitant about checking that box.

"One of the biggest myths we hear is that a person might not receive the lifesaving care they require if they're registered as a donor," says Dr. Mobley. "This just isn't true. Everyone on your care team went into medicine for one reason: to help people. No one is thinking about organs that may or may not be eligible for donation. We're trying to save your life."

In addition, very strict rules are in place to prevent emergency and ICU care from overlapping with transplant patient care. This means the team caring for a critically ill patient who's registered to donate is completely separate from the team caring for a patient who's waiting for a transplant. And there's no communication between them.

Just bringing up the possibility of donation to a registered person who is very sick is coordinated by a separate team, facilitated by the organ procurement organization.

"It's not going to be the doctor or the nurse at the bedside caring for you who'll be talking to you about potentially donating," says Dr. Mobley. "It's all kept very separate so that the team caring for you is 100% focused on saving your life."

Another reason some people can be uncertain about organ donation involves conflicts with religious beliefs.

"We know some religions have concerns about organ donation, and we respect everyone's religious views," says Dr. Mobley. "But I would encourage anyone concerned to speak to their religious leaders about donation and whether the opportunity to provide new life is something that's possible for them to consider."

How to become an organ donor

If you'd like to register to become an organ donor, sign up through your state's motor vehicle department — online or at one of their local offices. You can use the HRSA's portal to help you determine where to start. Many states, including Texas, designate organ donor status by your license.

As a reminder, registering through your state to be an organ donor is different than signing up to be a living donor. Learn more at our Living Donor Center if you're interested in donating while you're alive. Additionally, the HRSA provides more information about the process for living donations.