Info

Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.

FIGURE 12-1 Schematic view of the drug-sensitive sites in prototypical synaptic complexes. In the center, a postsynaptic neuron receives a somatic synapse (shown greatly oversized) from an axonic terminal; an axoaxonic terminal is shown in contact with this presynaptic nerve terminal. Drug-sensitive sites include: (1) microtubules and molecular motors responsible for bidirectional transport of macromolecules between the neuronal cell body and distal processes; (2) electrically conductive membranes; (3) sites for the synthesis and storage of transmitters; (4) sites for the active uptake of transmitters by nerve terminals or glia; (5) sites for the release of transmitter; (6) postsynaptic receptors, cyto-plasmic organelles, and postsynaptic proteins for expression of synaptic activity and for long-term mediation of altered physiological states; (7) presynaptic receptors on adjacent presynaptic processes; and (8) on nerve terminals (autoreceptors). Around the central neuron are schematic illustrations of the more common synaptic relationships in the CNS.

FIGURE 12-1 Schematic view of the drug-sensitive sites in prototypical synaptic complexes. In the center, a postsynaptic neuron receives a somatic synapse (shown greatly oversized) from an axonic terminal; an axoaxonic terminal is shown in contact with this presynaptic nerve terminal. Drug-sensitive sites include: (1) microtubules and molecular motors responsible for bidirectional transport of macromolecules between the neuronal cell body and distal processes; (2) electrically conductive membranes; (3) sites for the synthesis and storage of transmitters; (4) sites for the active uptake of transmitters by nerve terminals or glia; (5) sites for the release of transmitter; (6) postsynaptic receptors, cyto-plasmic organelles, and postsynaptic proteins for expression of synaptic activity and for long-term mediation of altered physiological states; (7) presynaptic receptors on adjacent presynaptic processes; and (8) on nerve terminals (autoreceptors). Around the central neuron are schematic illustrations of the more common synaptic relationships in the CNS.

The brain clears metabolites of transmitters into the CSF by excretion via the acid transport system of the choroid plexus. Substances that rarely gain access to the brain from the bloodstream often can reach the brain when injected directly into the CSF. Under certain conditions, it may be possible to open the BBB, at least transiently, to permit the entry of chemotherapeutic agents. Cerebral ischemia and inflammation also modify the BBB, increasing access to substances that ordinarily would not affect the brain.

Was this article helpful?

0 0
Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

Get My Free Ebook


Post a comment