in humans glucose is kept in balance in the bloodstream by insulin which concept does this best illustrate

Homeostasis

Explanation:

Homeostasis is the maintenance of a steady-state/condition in the body to ensure the optimal workings of the cells. Blood sugar level is one of the variables in the body that also has to be maintained through positive and negative feedback loops to maintain the desired level. Insulin is the hormone used for negative feedback (to reduce the blood sugar level when it goes higher than the normal level) and Glucagon is the hormone for positive feedback (to raise the blood sugar level when it goes below the normal levels).