Gordon is walking down his street, sees an angry dog running toward him, and begins to run in the opposite direction. In addition to an increase in heart rate and blood pressure, he would also display an increase in which glucocorticoid hormone?

A) serotonin
B) estrogen
C) progesterone
D) cortisol

Cortisol is the primary glucocorticoid hormone that increases in response to stress, such as the fear induced by an angry dog chasing someone. It plays a key role in the body's stress response by increasing glucose in the bloodstream, enhancing the brain's use of glucose, and increasing the availability of substances that repair tissues.