Orgasm is a reflex of the autonomic nervous system.

And then the message cascades into the amygdala, and then goes down the autonomic nervous system.

So if the amygdala is excited, and this is something important, the messages then cascade into the autonomic nervous system.

Neuropathic pain, by contrast, arises after a lesion or disease affects the nervous system. Nerve damage resulting from diabetes (diabetic neuropathy) and persistent pain after shingles (postherpetic neuralgia) are among the most common causes.

For example, in two Northern Provinces, there have been serious food shortages crises, caused by tropical neuropathy (due to consumption of bitter cassava, improperly processed) by people with deficient nutritional state, specifically those with protein deficiency.

Many chemical mediators are involved, including cortisol and adrenalin from the adrenal glands, other hormones and neurotransmitters (such as serotonin and noradrenalin), and responses from the autonomic and immune systems. Depression thus leads to changes in the rest of the body, owing to long term chemical imbalances in the systems that control the heart, the immune system, and metabolism.