Final answer:
Possible explanations for excessive epinephrine signaling symptoms include elevated numbers of epinephrine receptors, elevated acetylcholine secretion, or a tumor in the adrenal medulla.
Step-by-step explanation:
Excessive epinephrine signaling can lead to a high heart rate, high blood glucose, high blood fatty acids, and anxiety. However, if circulating levels of epinephrine seem normal, there can be other reasonable explanations for this pattern.
One possible explanation is that the person has elevated numbers of epinephrine receptors. This means that even normal levels of epinephrine can have a stronger effect on the body due to the increased number of receptors.
Another possible explanation is that the person has elevated acetylcholine secretion. Acetylcholine is a neurotransmitter that counteracts the effects of epinephrine. If there is an increase in acetylcholine secretion, it can suppress the symptoms caused by excessive epinephrine signaling.
Lastly, the person having a tumor in the adrenal medulla can also explain the symptoms. A tumor in the adrenal medulla can lead to the overproduction of epinephrine, even if circulating levels appear normal.