Circumventricular organs

Circumventricular organs are sites in the neuroendocrine system that allow factors to 'circumvent' the Brain Blood Barrier. These organs secrete or are sites of action of different hormones, neurotransmitters and cytokines.

Examples
Circumventricular organs include the following:
 * Pineal gland - secretes melatonin and is associated with circadian rhythms
 * Subfornical organ- regulates body fluids
 * Organum vasculosum of the lamina terminalis- detects peptides
 * Choroid plexus
 * Area Postrema- the vomiting centre of the brain (makes sense that the brain can detect noxious substances in the blood and stimulate vomiting in order to rid the body of the substances)
 * Median eminence- regulates the anterior pituitary through the release of neurohormones
 * Subcommissural organ
 * Posterior pituitary (neurohypophysis)- to detect levels of oxytocin and ADH in the blood