Jack's primary care doctor retired recently. It was a life-changing experience — for Jack.

He'd been seeing the guy for more than 20 years and had come to respect his skills and even his gruff, no-nonsense manner. "Many times when he'd walk into the room," Jack recalled, "he'd take one glance at me and growl, ‘Let's find out why you look like crap.' "

Jack liked that in his doctor.

One day a few months ago, Jack, who turned 60 last year, woke up feeling lousy: shortness of breath, hacking cough, chills. He called the number he'd always called, made an appointment and showed up at the same medical office adjacent to his hospital, forgetting about the letter he'd received announcing that Dr. Goodman was retiring but that his practice would continue with other clinicians.

This time when the door to the exam room opened, a lanky young man with long blond hair and trendily cropped whiskers strode in. He was wearing a white coat over jeans. "He was smiling from ear to ear," Jack told me. "Beaming." In the two and a half decades Jack had been going to Dr. Goodman, the physician never once beamed. As far as Jack can recall, Dr. Goodman never so much as cracked a smile in his presence.

"He was stern," Jack said. He liked that in his doctor.

"I'm Chace," the blond man cheerfully announced, and instead of shaking Jack's hand, patted him warmly on his upper arm. Jack tensed, fearing he was about to be pulled into one of those guy hugs he saw so many young men giving each other nowadays.

"Nice to meet you, Dr. Chace," Jack said.

The young man laughed. "No, no, not Dr. Chace. Just Chace. I'll be your nurse practitioner."

Jack took a minute to absorb that information. He'd heard of nurse practitioners. He had nothing against nurse practitioners. But he'd come to see an M.D.

Chace must have noticed his unease. "Don't worry, I actually went to school for this," he said with another laugh. "I'll be examining you to find out just what's up and, if you need it, I'll call in your prescription."

"You can do that?" Jack asked. "Legally?"

"Sure can," Chace guffawed, "believe it or not."

Jack's instinct was toward the not.

"This kid was half the age of any doctor I'd ever been to," Jack said. "He was half my age." Plus, he was male. Jack, of course, knew men could be nurses, but up to that very moment, he had never actually met a male nurse.

It also occurred to him that after all those years of going to Dr. Goodman, he had no idea what his first name was. "But," Jack told me, "I'd be willing to bet money it isn't Chace."

As it turned out, the examination was just like any other routine medical exam Jack had ever received, except that Chace talked more, laughed more and clicked away at the computer more than Jack was used to. In the end, he made a diagnosis and prescribed a medication, and within a day or two, Jack felt good as new. What surprised Jack was that Chace sent him an email immediately after the appointment with his personal medical record attached. Jack isn't certain what he's supposed to do with it, but he suspects it's a good thing to have. What surprised him even more was that Chace called him on the phone a couple of days later to make sure he'd filled his prescription, was taking it properly and that it was having the desired impact, with no side effects.

Jack is well-read and keeps up on current events. For somebody not in the medical profession or actively involved in politics or policymaking, he understands to a surprising degree how health care is changing in significant ways.

"I know that these changes are needed and that in the end it'll be good for patients and for the whole system," he said. "And I guess I'll even get used to seeing a nurse practitioner more often than a doctor. A really young nurse practitioner." He shook his head. "But then everybody in health care seems so young to me now."

The bottom line? "I'm set in my ways," Jack said with a sigh. "It'll take me awhile to adjust."

As the baby boom generation ages, veteran health care professionals will retire at an evermore rapid pace to be replaced by a younger generation with some new ways of doing things, sometimes by personal choice and sometimes because the evolving system mandates it. At the same time, the proportion of senior patients will grow by leaps and bounds. No doubt it'll take many of us awhile to adjust to the changes coming our way, whether we're physicians, nurses, hospital executives, hospital staff or — and let's face it, sooner or later this means all of us — patients.