CNS diseases Flashcards
what are meninges?
membranes between the inner side of the skull and the neurons of the brain
where is the CSF formed?
in the ventricle’s choroid plexus
where does CSF flow? how does it get absorbed?
through the ventricles into the subarachnoid space via the median and lateral apertures. Some CSF flows through the central canal of the spinal cord.
Gets absorbed in the dural venous sinuses via the arachnoid villi.
what are the 3 types of glial cells? describe
- oligodendrocytes: analogs of the Schwann cells in periphery (production of myelin sheath on axons)
- astrocytes: control neuron’s microenvironment. caretaker cells of the neurons.
- microglia: variant macrophages (immune cells in the brain)
what’s an abscess?
local area of tissue destruction due to infection.
liquefaction inside the brain.
what brain bacterial infections are neonatal and young children most prone to?
E. coli and haemophilus influenzae
does tha brain have good immune response?
it is very resistant, but has weak defense if a bacteria establishes itself.
where in the brain does inflammation happen?
meninges
where do microorganisms often grow?
subarachnoid space
layers of meninges from inner to outer
pia mater, arachnoid, dura mater
what is meningitis and name the symptoms
inflammation of the meninges, usually confined to subarachnoid space.
fever, headache, stiff neck, mental alterations, photophobia
what fills the subarachnoid space in meningitis?
purulent exudate (neutrophils and bacteria)
what 3 bacterias can cause meningitis in adults?
E. coli, streptococcus pneumoniae, Neisseria meningitis
where is Neisseria meningitis most present?
Africa
how does Neisseria meningitis infect people?
it colonizes the nasopharynx and secretes proteases that inactivate IgA so they can cross the epithelium and enter the bloodstream which gives them access to the brain where they invade non-ciliated cells
pathogenesis of meningitis caused by Neisseria meningitis (like the steps)
- Adhesion to non-ciliated epithelium
- Production of an IgA protease.
- Has a polysaccharide capsule that inhibits phagocytosis. The capsule can mimic
neural cell adhesion molecules. - They can vary the surface expression antigen.
- Immune system is triggered by endotoxin.
- Neutrophil proteolytic enzymes damage the endothelium.
- Shock, intravascular thrombosis, and system failure
what does the inflammatory reaction following meningitis cause?
- vasculitis and cerebral ischemia
- BBB disruption, hydrocephalus, cellular swelling causing cerebral edema
what bacteria can pass through the endothelium of the cerebral vasculature
without any disruption of the endothelium?
E. coli with a K1 capsule
what are the 2 forms of neural injury in meningitis?
necrotic cortical injury and apoptotic hippocampal injury
how can we cure meningitis?
no therapy found, only antimicrobial treatment
meningitis can arise from complication of what disease?
tuberculosis