Which of the following hormones is linked to the depolarization of the GI tract?

The hormone linked to the depolarization of the gastrointestinal (GI) tract is acetylcholine. Acetylcholine is a neurotransmitter that plays a significant role in the autonomic nervous system, particularly in stimulating smooth muscle contraction in the GI tract. When acetylcholine binds to its receptors on the smooth muscle cells of the GI tract, it causes depolarization, leading to the propagation of action potentials. This process facilitates peristalsis and other contractions necessary for digestion and movement of food through the gastrointestinal system.

While hormones such as insulin and gastrin do influence digestive processes, they do not directly trigger the depolarization of smooth muscle cells in the same manner as acetylcholine does. Cortisol, a steroid hormone, is primarily involved in the regulation of metabolism and stress responses and does not play a direct role in the depolarization of the GI tract. Understanding the roles of these substances clarifies the essential conducting role of acetylcholine in the digestive physiology.