Key Terms
Central nervous system (CNS)
Brain and spinal cord. Peripheral nervous system (PNS): network of nerves connecting CNS to muscles and sensory structur
Layers from outside in
1. Scalp (outer skin) 2.
Cerebrospinal fluid (CSF)
Watery fluid produced by choroid plexus (cuboidal epithelial cells surrounding capillary beds in brain ventricles); deli
Spinal cord has same protective structures
Dura mater (dural sheath), arachnoid mater, pia mater, plus blood-spinal cord barrier.
Function
Limits transfer of blood components (including pathogens and most drugs) into CNS.
Clinical problem
Most drugs (including antiretroviral therapies and anti-cancer drugs) cannot cross the BBB. Brain becomes a reservoir fo
Glial cells (neuroglial cells)
Support neurons, provide scaffolding, aid in recovery from injury.
Neurons
Transmit signals via electrochemical processes.
Meningitis
Inflammation of the meninges. Encephalitis: inflammation of brain tissue.
Symptoms of meningitis
Severe headache, fever, photophobia, stiff neck, convulsions, confusion. Additional symptoms in encephalitis: lethargy,
Skull creates a problem
Swelling has nowhere to go; increased intracranial pressure damages brain tissue.
Diagnosis
MRI and CT scans (primary method — detect cysts); elevated blood eosinophils (parasitic infection indicator); EIA and EL
Entry routes
Bloodstream (after trauma or from bacteria crossing mucosal barriers); spread from upper respiratory structures (orophar
Most common non-neonatal causes
Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae. All three spread by respiratory secretions.
Organism
Larval form of pork tapeworm. Leading cause of ADULT ONSET EPILEPSY in the developing world.