This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2017, Subject name: Physiology
[{'content': 'Which of the following ion plays role in exocytosis? \nSelect and explain. \nA. Sodium, B. Potassium, C. Calcium, D. Magnesium', 'role': 'user'}, {'content': "Answer: C \nExplanation: Exocytosis For exocytosis to occur, the vesicle containing neurotransmitter must fuse with pre-synaptic membrane - Vesicle membrane is negatively changed & also the cell is negatively charged. Therefore for this fusion to occur a bridge should be formed & a cation can form this bridges. that cation is Ca2+ - Exocytosis, in most cases, is stimulated by the entry of calcium ions into the cell: Calcium ions interact with vesicular membrane in some way that is not understood and its fusion with the cell membrane followed by exocytosis - That is opening of the membrane's outer surface and extrusion of its contents outside the cell.", 'role': 'assistant'}]