Lateral hypothalamus an OX1-induced CB1 pressor response in the rostral ventrolateral medulla. Narcolepsy is associated with a marked reduction in the number of orexinergic projection neurons from the lateral hypothalamus and very low orexin peptides in cerebrospinal fluid. This has been identified as the mechanism responsible for narcoleptic symptoms. Evidence suggest that OX1 neurons that synapse onto the dorsal nucleus of the vagus nerve and parts of the brain stem may play a role in the pathophysiology of chronic pain and visceral hypersensitivity in functional gastrointestinal disorders. Lateral hypothalamus The lateral hypothalamus, also called the lateral hypothalamic area, contains the primary orexinergic
Medulla (hair) Medulla (hair) The medulla is the innermost layer of the hair shaft. This nearly invisible layer is the most soft and fragile, and serves as the pith or marrow of the hair. Scientists are still uncertain about the exact role of the medulla, but they speculate that it is primarily an extension that is more prominent in depigmented (grey or white) hair Human hair is unique in that its medullary index (the fraction of the hair shaft's diameter that the medulla occupies) is very small: generally less than 1/3. Other species will have much larger ratios, usually at least 1/2.