Overview Snapshot A 56-year-old female is brought to the emergency department by her daughter due to new-onset abnormal movements suggestive of a seizure. While the patient is being managed, the physician learns that the patient is being treated for lung cancer. Head CT was obtained after the patient was stabilized. Introduction Structure tight junctions between nonfenestrated capillary endothelial cells also consists of astrocytic foot processes, pericytes, basement membrane irradiation, malignancy, infection can disrupt the blood-brain barrier (BBB) infarction destroys tight junctions → vasogenic edema fluid is extravasated into the interstitial space Function control entry of substances into the brain substances cross via diffusion, ion channels, and selective transport proteins diffusion: nonpolar/lipid-soluble substances readily cross the BBB O2, CO2, heroin, nicotine ion channels: movement of Na+ and K+ selective transport proteins: nutrients glucose, amino acids, peptides removes metabolites certain areas of the CNS lack a BBB posterior pituitary (neurohypophysis) allows ADH release from brain into systemic circulation area postrema chemotherapeutic drugs → vomiting organum vasculosum lamina terminalis (OVLT) senses blood osmolality