四川大学期末考试试题I. Explain the following terms (24 points, 3 for each) 1. action potential ： A rapid, reversible and conductible fluctuation of the membrane potential of cell when stimulated.2. gastrointestinal hormones: Biologically active polypeptides secreted by the endocrine cells in gastrointestinal tract which influence the motility and secretion of gastrointestinal tract. 3. cardiac cycle: The period from the beginning of heart contraction to the beginning of next is called a cardiac
