adrenaline is released from the adrenal medulla

answer of plasticity is on the mark, although I think a term that more readily describes the system's ability react over a greater time scale would be impedence matching. Chromaffin cells are dervived from neurons, but the presence of a regulated secretory pathway is a hallmark of endocrine tissues. You've already highlighted the physiological effects of those hormones, and I would ad dopamine as the other major secretory hormone/neurotransmitter.

First and foremost, it fits the definition of an endocrine tissue, which is to produce and secrete hormones in a regulated manner. I would argue that the adrenal medulla is a real endocrine tissue for the following reasons. Posts with unsourced content may be edited or deleted. Want to improve this post? Add citations from reputable sources by editing the post. So what is the purpose of the adrenal medulla, if all of the effects which the endocrine adrenalin produces are essentially the same as those produced by the sympathetic mass response? In fact, its chromaffin cells are modified neurons by descent and secrete adrenalin and some noradrenalin upon stimulation by sympathetic preganglionic fibres, effectively turning the medulla into a sort of 'endocrine ganglion' with the whole cardiovascular system as its 'postganglionic fibres'.Īdrenalin in the circulation seems to have pretty much the same effect as all the adrenergic neurons of the sympathetic nervous system (which innervates all blood vessels, organs etc.): arteriole constriction, cardiac output increase, breath rate increase, pupil dilation, glucagon secretion and insulin inhibition, stimulation of glycolysis and glycogenolysis etc. The adrenal medulla is less of a 'real' endocrine organ like the others in the endocrine system and much more an extension of the sympathetic nervous system.

Adrenaline is released from the adrenal medulla