CARRBORO - Anna McCullough was only three or four weeks into her master's program at the UNC School of Social Work when she volunteered at a Carrboro free clinic run by students from the School of Medicine and other medicine-related disciplines taught at UNC.

But she remembers helping a patient in mental crisis feel more stable that first night and linking him to resources that could assist him.

"I thought, 'This is what it's all about,' " McCullough said.

On Sunday, McCullough invited current and former student volunteers and the faculty who support them to a celebration at the Carrboro ArtsCenter, marking 40 years of the Student Health Action Coalition, known as SHAC.

The organization runs a free medical clinic every Wednesday night in the Piedmont Health Services clinic in Carrboro and a twice-weekly dental clinic in Carr Mill Mall.

SHAC has made its place in history by being the longest existing student-run free clinic in the United States, said Jim Emory, who researched the history for his master's degree in public health.

SHAC is unique in its interdisciplinary approach and its community-service focus, Emory said. Students who volunteer are challenged to learn from the community they serve.

When Hallam Gugelmann volunteered as a student leader at the clinic two years ago, he learned that there was a need for free dermatological services. A new relationship was formed with UNC's dermatology department, and a woman who had recently arrived from Mexico was able to get a large skin cancer removed from her nose as a result, Gugelmann said. Now, a dermatology clinic is offered twice a month.

Seven disciplines at UNC work together to run the clinic -- medicine, nursing, dental, pharmacy, physical therapy, social work and public health. Faculty members in UNC's Department of Family Medicine take turns overseeing the students running the clinic.

Tom Wroth, a UNC faculty member in the Department of Family Medicine, has been doing just that, and is now stepping up his involvement by becoming a faculty adviser to SHAC.

Wroth said providing medical care to underserved patients feels good.

"If you have a patient who hasn't had medical care in 15 years and you diagnose that patient with hypertension or diabetes, that can be a lot more satisfying than fine-tuning someone who has a lot of monetary resources," Wroth said.