Dilated pupils, inhibited digestive activity, increased respiratory rate, and release of glucose from the liver are all signs of activity of

The answer would be: the sympathetic division of the autonomic system.

Sympathetic division of the autonomic system causes the person to enter fight or flight mechanism. All of the changes above will prepare the person for it. Increased breathing will increase oxygen delivery for muscle, sugar release will increases energy produced, inhibition of digestive system conserve the energy,