Adrenal medulla secretes two hormones called adrenaline or epinephrine and noradrenaline or norepinephrine (also called emergency hormones). Both the hormones - - Cause pupillary dilation (not constriction) - Stimulate breakdown of glycogen resulting in increased concentration of glucose in blood i.e., cause hyperglycemia. - Cause piloerection (raising of hair). - Increase strength of heart contraction i.e. heartbeat.