PHRM 211 Lecture Notes - Lecture 1: Chemoreceptor Trigger Zone, Endothelium, Tight Junction
Document Summary
Anatomical basis located in specialized endothelial cells of brain capillaries. Endothelial cells have extensive contact with projections from astrocytes (aka glial end-feet) Brain endothelial cells are joined by tight junctions of astrocytes (left, right diagrams) Peripheral endothelial cells have large pores fenestra (middle diagram) Substances are moved across the brain endothelial cell membranes in various ways. Tight junctions ( a ) allow only water soluble molecules to pass through. Lipid bilayer ( b ) lipid soluble molecules and drugs can cross directly (the greater the lipophilicity, the faster they cross and enter into the brain) Transporter proteins ( c ) certain molecules (e. g. glucose, aa, nucleosides) cross. Special receptor-mediated transcytosis mechanisms ( d, e ) e. g. insulin. Not all areas of the brain have a bbb (chemoreceptor trigger zone). Substances entering the brain are generally referred to as crossing the bbb . Lipid solubility index more lipid soluble, crosses bbb quicker.
