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They're often the first people you see at the doctor's office, and the first line of defense in any ER - but America's nursing population is shrinking fast.

The nursing shortage may not be caused just by lack of interest. In many ways, it's caused by lack of capacity. Each year, 80,000 applicants are turned away from nursing schools, often because there aren't enough teachers or resources to accommodate growing student interest.

"Suddenly, we turned around and realized we're not attracting enough nurses to go into teaching," said Dr. Kimberly S. Glassman, with patient care services and the chief nursing officer at NYU Langone Medical Center.

"The fear is we will have to shrink the number of nurses we can prepare for the future at a time when we need to prepare more."

Many of America's nurses are about to reach retirement age just as the baby boomer population is growing in its health care consumption - compounding the urgency of the situation.

"In addition to not having many student placements, and the retirement issue on the part of the faculty, the slowness at which we can prepare these nurses to serve as teachers has really come together at a time when we really want to increase the numbers, but we find that we are restrained," said American Nurses Association President Pam Cipriano.

But Glassman is quick to eschew a doomsday scenario, saying, "This is not something you're going to feel day to day. … This is something that we and other universities are paying attention to."

The ANA is taking note, as well, working to help fund scholarships and encouraging nursing students, as well as current registered nurses, to take advantage of doctoral and masters programs, providing them with a window to one day move into a faculty position.

"On the one hand, we think that the position is getting better," said Cipriano. "But on the other hand, we know it can take years before we can change the equation, before we have sufficient numbers of slots for those 80,000 candidates that are being turned away."

Glassman noted that larger institutions such as NYU Hospital and similar facilities in major cities are not the ones that are suffering the most. It's the institutions in smaller, more rural areas that will see a more rapid change in a shorter amount of time.

To that end, the ANA will be canvassing the halls of Congress this January in an effort to double down on funding efforts for schools and scholarship programs.

In the meantime, Cipriano said, she's focused on one basic question: "How can we redesign care? What are the care methods that will allow us to use the nurses we have in the most effective manner?"