Executive Team

Gar Atchison, MBA

Chief Executive Officer, Market President

Gar is the Chief Executive Officer for UP Health System – Marquette and the Market President for UP Health System - Bell, Marquette, and Portage. Gar has been with UP Health System since December 2019. He is a seasoned leader who is deeply committed to UP Health System’s mission of Making Communities Healthier.

A veteran healthcare executive with more than 30 years of experience, Atchison joined UP Health System from Frye Regional Medical Center, another Duke LifePoint facility in Hickory, North Carolina. During his tenure there, he served in several leadership positions, including as chief operating officer (COO), vice president of business development, and market operations director for the hospital’s physician network, before assuming the role of CEO in 2016.

Prior to his time at Frye Medical Center, Atchison served as CEO of Hickory Orthopedic Center, PA, a multi-location orthopedic practice in Hickory, North Carolina. Before that, he was a practice administrator for Bay Street Orthopedics in Petoskey, Michigan, and financial operations manager for Northern Michigan Hospital, also in Petoskey.


Tonya Darner, MBA

Chief Operating Officer

Tonya is the Chief Operating Officer for UP Health System – Marquette. Tonya previously served in progressive leadership roles at UP Health System – Marquette before returning as COO in October 2021. Tonya is a proven leader with 25 years of experience in medical practice management and healthcare administration, successfully overseeing operations of complex clinical teams, budgets, and overall care for large volumes of patients.

Tonya served as an officer in the U.S. Air Force for 20 years, eventually becoming the 4th Medical Operations Squadron Superintendent in 2007. After retiring from the military, Tonya managed operations for several busy medical practices in the Marquette area through progressive leadership roles at UP Health System – Marquette; including Senior Director of neurosciences, imaging and on-call specialists service lines, and Director of Regional Operations for neurosciences, occupational medicine, behavioral health, pediatric specialty clinics, and radiology service lines. Most recently, Tonya served as the COO for Aspirus Wausau Hospital in Wausau, WI.


Sherry Henderson, MBA

Chief Financial Officer

Sherry is the Chief Financial Officer for UP Health System – Marquette. Sherry has been with UP Health System since April 2017. She is a seasoned finance executive with more than 25 years of experience in corporate and operational healthcare finance. Sherry previously held various roles in Tenet Healthcare and Piedmont Healthcare.

Sherry obtained her BBA in Accounting from Sam Houston State University and her MBA in Healthcare Management from the University of Phoenix. She attended Mercer University, Stetson School of Business and Economics receiving a black belt in Quality and Process improvement and also participating in the Studer quality training.

Sherry is an active participant in the community, serving on various boards in each area she lives in and most recently on the boards of Trillium House and Economic Club in Marquette.


Christine Stryker, MBA, MSN, RN

Chief Nursing Officer

Christine is the Chief Nursing Officer for UP Health System – Marquette. Christine joined UP Health System in May 2021, bringing to the organization over 25 years of progressive leadership and management experience in nursing, patient services, and business operations in hospital settings large and small, urban and rural.

Christine has served as Chief Nursing Officer in both New York and Pennsylvania as well as Assistant Vice President of Nursing at Montefiore University Hospital in the Bronx, and Associate Nursing Officer at Upstate University Hospital Community Campus in Syracuse New York. Christine has also worked as a Heart Center Director and a Practice Administrator for a group of Cardiac surgeons.

Christine earned her bachelor’s degree in Nursing from Vermont College of Norwich University. She then earned her Master’s in Nursing from the University of Vermont and her Master’s in Business Administration from DeSales University in Pennsylvania.


Board of Trustees

Jerry Napier, MD, Chair
Gar Atchison, CEO, Secretary
Lisa Long, MD, Chief of Staff
John Bartlett, MD, Trustee
Dan Greenlee, Trustee
Christine Greer, Trustee
Gary LaPlant, Trustee
Dave Manson, Trustee
Tami Seavoy, Trustee
MaryAnne Shannon, PhD, RN, Trustee
William Short, MD, Trustee
Linda Sutton, MD, Trustee
Judy Watson-Olson, EdD, Trustee