Desiree Ramos was watching a science film in her ninth-grade homeroom at New Foundations Charter School when she began to feel shaky - a sign she knew meant low blood sugar.

Ramos, a type 1 diabetic since age 5, whispered an explanation to her teacher and headed to the nurse's office. She deftly pricked her finger and watched as a test strip swallowed the tiny bead of blood. Within seconds, her glucose meter registered 42 (normal blood glucose is between 80 and 180). "I was a little scared," she recalls. "But I know how to manage it." She grabbed a juice container from the mini-fridge and sat down to rest.

It was just another day in the office of nurse Cheryl Cantwell, who teaches students like Ramos how to practice such calm and skilled self-care. At first glance, the place looks familiar, almost retro: glass jars for bandages and cotton puffs; eye chart with its all-caps K-H-O-R-Z.

But yank open Cantwell's closet, and the 21st century of school nursing appears: A vinyl shoe caddy holds 20 boxes of prescription drugs, mostly Ventolin, a rescue inhaler for asthma, and a chart lists students with allergies to red dye, coconut, strawberries, peanuts, shellfish, and eggs. A cabinet holds medical records for each of the school's 725 students, including some with obsessive-compulsive disorder, anxiety, attention deficit hyperactivity disorder (ADHD), cerebral palsy, Tourette's syndrome, autism, and seizure disorders.

The school nurse - once the person who doled out antiseptic for playground scrapes and Motrin for menstrual cramps - has morphed into a multi-tasking, holistic health-care provider who cares for students with chronic illnesses and meets stepped-up screening requirements (annual weight, height, body-mass index, and vision checks for all students, along with hearing and scoliosis screens for some). And in an era when many families are pinched for health insurance and time, the nurse often becomes the go-to medical resource, even for injuries or illnesses that happen at home.

"My role has expanded so much in the last few years," says Cantwell, who was a pediatric nurse for 10 years before joining the school system. "The first aid and the boo-boos are this much" - she holds her thumb and index finger a syringe-width apart - "of what a nurse does," she said.

Cantwell, 40, remembers watching her aunt pull on a crisp white cap and uniform to go to work at Frankford Hospital (now Aria Health's Frankford campus). "From the time I was 6, I wanted to be a nurse." She endured two years of trial-by-avalanche at a Philadelphia elementary school before coming to New Foundations, a K-to-ninth-grade charter school in the Northeast, in 2003. "The kids were so needy. It was just triage all day long."

At New Foundations, just 10 minutes from her Torresdale home, Cantwell considers herself lucky. She has a full-time assistant, Mary Witalec, a licensed practical nurse, and she has time to teach: lessons on sun safety to younger kids, the "puberty talk" for fifth graders, instruction on new CPR techniques to faculty.

Pennsylvania ranks 17th among states in the ratio of students to school nurses, with an average of 789 (the National Association of School Nurses, NASN, recommends a ratio of 750 well students to one nurse, with lower ratios if special-education students or those with chronic illnesses are included). New Jersey fares even better, ranked 7th with an average of 512 students per nurse.

There is no shortage of certified school nurses, only a dearth of funded positions, especially in these budget-slashing times. The Philadelphia School District budget, adopted last month, would eliminate 50 full-time nurses, whose salaries average $74,300 (district teachers get $63,300 on average). "When superintendents are . . . trying to balance the budget, school nurses are often the ones to be cut, which is frustrating to us. Kids need to be healthy to learn," says Sandi Delack, president of the NASN.

The association offers a big-picture view of today's students: 33 percent are obese or overweight; 13 percent take long-term medication; 10 percent have asthma; 5 percent have food allergies; 5 percent have been diagnosed with ADHD.

"We're seeing a lot more medically fragile children," says Karen Flad, president of the Pennsylvania Association of School Nurses and Practitioners. "And poor children who don't have the same access to health care. School nurses become the eyes and ears, knowing the subtle things to look for before they become emergencies."

In the case of one elementary-age student, Cantwell and the girl's teacher were the first to see the signs: The girl called out, rocked her chair, and jumped from her seat in constant, agitated motion. Cantwell thought she should be tested for ADHD. But the girl's mother, Kathleen Henes, didn't want to hear that.

"I didn't want to believe she had ADHD. I felt like I had failed as a parent." Henes and her ex-husband finally had their daughter tested by the school's psychologist and her own pediatrician; both diagnosed her with the attention disorder, and both recommended medication.

The last week of May, Cantwell met with the parents, the girl's teacher, the principal, and the psychologist. She tried to reassure both parents that their daughter's ADHD was neither their fault nor her own. "I said, 'Don't feel bad. Don't feel like the Lone Ranger. There's plenty of kids we're trying to help.' "

Henes said later that she was impressed by Cantwell's expertise and by the school's pledges to help her daughter by seating her near a teacher and giving her step-by-step directions for tests and activities.

"[Cantwell's] opinion really matters to me because she is the school nurse," Henes said. "She went above and beyond to calm me down."

It helps, Cantwell says, that she is a parent - her kids are 11, 8, and 5. That experience helps her discern which stomachache is due to too much pizza and which one is due to an algebra test; it reminds her that sometimes a moment of kind attention is the most potent medicine.

Her manner - no-nonsense, good-humored, seemingly unflappable - stays consistent even during a hot late-May week that includes a brief power outage (while she was checking an asthmatic student), a wheezing teacher, a second grader with a chalk-pale face ("I throwed up in the bathroom"), another teacher in search of a tampon ("second drawer," Cantwell directs, using the code she devised for embarrassed middle-school girls), and an eighth-grade boy who eagerly lifts his khaki shorts to reveal a large, oval scar - "the worst injury I've ever had here," Cantwell said. The boy, then in fourth grade, ripped his knee on an outdoor spigot while playing freeze-tag. "You could see the muscle, the fat, the tendons. It was like a picture in a textbook."

Amidst the unpredictable parade, Cantwell is packing up and planning for fall: All those shoe-pocket medications must go home by the last day of school; if not, she'll stand over a toilet and flush them. She'll put in a $500 supply order that includes 1,500 Band-Aids and 500 ibuprofen capsules. She'll compile her stats for the state: Just in May, students visited her office 304 times for illness and 56 times for injuries; she gave 77 doses of Tylenol or Motrin, 54 doses of ADHD meds, and 14 Tums.

"I used to think people who had this schedule had it made. But you need that three-month break. All I want to do is plant myself in a beach chair."

First, though, there's an eighth-grade sex education class on sexually transmitted infections. Cantwell considers this preventive medicine; the Philadelphia Department of Public Health recently declared that STIs (formerly called STDs, or sexually transmitted diseases) have reached "epidemic proportions" among city teens, with one in eight girls aged 15 to 19 diagnosed with chlamydia or gonorrhea in 2010.

In the school's spacious lecture hall, Cantwell peppers the 23 students with questions: "What symptoms would you have if you had an STI?" The kids squirm and look away. Finally, someone ventures, "Pain."

"Where?" Cantwell presses. "In your wrist? In your ankle?" Giggles. Silence. "In your private area," one boy says.

The students watch a video that advises abstinence but also notes that "if you choose to have sex, the best way to prevent STDs is with a condom and spermicide."

Afterward, Cantwell wants to know what they've learned.

"Birth control pills don't prevent you from getting STDs," says a girl.

"I learned what PID was. Um, periodic . . . inflammable . . . " Cantwell corrects the student: "Pelvic inflammatory disease."

The class ends, and students rise to leave. One boy lingers in the aisle. "Mrs. Cantwell, what's a dental dam?"

For the first time all week, Cantwell seems a little thrown off her game. Is this really the moment to explain that a dental dam is a latex barrier held over a woman's genitals during oral sex, to protect both partners from disease?

She gives the boy a level gaze. "We'll talk about that tomorrow."

Contact Anndee Hochman at aehoch@aol.com.