More early signs of pregnancy include an aching head, a result of changes in hormones. Just in case you are indeed pregnant, take pg-safe acetaminophen instead of ibuprofen to deal with the pain.
Organs Without Dual Innervation. Although most organs are innervated by both sympathetic and parasympathetic nerves, some-including the adrenal medulla, arrector pili muscles, sweat glands, and most blood vessels-receive only sympathetic innervation.
Sympathetic nervous system. The sympathetic nervous system (SNS) is part of the autonomic nervous system (ANS), which also includes the parasympathetic nervous system (PNS). The sympathetic nervous system activates what is often termed the fight or flight response. Like other parts of the nervous system, the sympathetic nervous system operates through a series of interconnected neurons. Sympathetic neurons are frequently considered part of the peripheral nervous system (PNS), although there are many that lie within the central nervous system (CNS).