What are neural stimuli?

This is where hormones are released directly due to stimulation of the endocrine gland by nerves. An important example of this is the release of adrenaline and noradrenaline (the catecholamines) from the adrenal gland in response to stimulation by the sympathetic nervous system. This part of the nervous system is not under voluntary control and is activated in situations of sudden stress, such as conflict or fear (the so-called 'fight or flight' response). It is also activated in times of physiological stress (such as severe dehydration or very low blood pressure). In such situations the sympathetic nerves are activated, some of which stimulate the adrenal gland to secrete large amounts of adrenaline and noradrenaline, producing a wide range of physiological effects.