Vertebrates have two major communication and control systems: the endocrine system and the nervous system. Choose the correct statement describing the coordination of these systems.
A. Epinephrine functions as a hormone in the endocrine system and as a neurotransmitter in the nervous system.
B. The parathryroid gland is a fused endocrine and neuroendocrine gland.
C. The adrenal cortex secretes hormones in response to nervous stimulation.

A. Epinephrine functions as a hormone in the endocrine system and as a neurotransmitter in the nervous system.

Explanation: Epinephrine can act as a hormone and also as a neurotransmitter. Epinephrine can also be referred to as adrenaline.

The adrenaline is a hormone that is secreted mainly by the medulla of the adrenal glands and the Epinephrine primary function is to increase cardiac activities and also to increase the level of glucose in the blood. Its actions vary by tissue type and tissue expression of adrenergic receptors. Epinephrine acts on nearly all body tissues.