Question

When the neurotransmitter acetylcholine binds to the surface of a smooth muscle cell within the wall of the stomach, the muscle cell is stimulated to contract. When a foreign antigen binds to the surface of a mast cell, the cell is stimulated to secrete histamine, a substance that can trigger the symptoms of an allergy attack. Both of these responses, one leading to contraction and the other to secretion, are triggered by the same second messenger. Which second messenger is being discussed?

Answer 1

The second messenger likely involved in both muscle contraction in response to acetylcholine and histamine release from mast cells in response to antigens is either calcium ions or cyclic adenosine monophosphate (cAMP).

Step-by-step explanation:

The second messenger being discussed that can lead both to the contraction of smooth muscle in the stomach and the secretion of histamine from mast cells is likely calcium ions (Ca2+) or cyclic adenosine monophosphate (cAMP). When acetylcholine binds to the surface of a smooth muscle cell in the stomach's wall, it can trigger an increase in intracellular calcium levels, which results in muscle contraction.

On the other hand, when a foreign antigen binds to a mast cell, it causes the cell to release histamine, which can provoke allergy symptoms. This process is also mediated by an increase in intracellular calcium or changes in cAMP levels, which are second messengers generally involved in signaling pathways in cells.