BBB, CSF etc

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BBB, CSF etc
2012-12-05 12:21:49
NHB BBB CSF choroid

BBB, CSF lecture notes
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  1. Adult brain blood flow
    700-800ml/min = 50ml/100g/min
  2. Changes in blood flow
    • <20 ml/100g/min: ischaemia
    • <10: infarction
    • >60: hyperaemia - raised pressure/indicative of tumour
  3. 3 types of strokes
    • Thrombotic (50%): plaques
    • Embolic (30%): dislodged clots
    • Haemorrhagic (20%): bursts
  4. Define transient ischaemic attack
    Stroke lasting for <24 hours: can indicate risk of major stroke
  5. Blood supply of bits of brain
    • Ant. Cerebral: medial aspects of cortical hemispheres forward of parieto-occipital border
    • Mid. Cerebral: lateral aspects of cortical hemispheres, basal ganglia, internal capsule
    • pos. cerebral: occipital lobe, pos-inf surface of temporal lobe, diencephalon, midbrain
    • Sup. Cerebellar: and pons
    • ant. Inf. Cerebellar: and pons
    • pos. inf. cerebellar: and medulla
  6. Features of BBB
    Tight junctions, astrocytic foot processes
  7. Function of BBB
    • Prevent exogenous toxins reaching brain
    • Prevent harmful endogenous substances reaching brain
    • Allow essential substances to reach neurones and glia
  8. Things and how they are transported across BBB
    • Facilitated diffusion: amino acids, glucose, L-DOPA (via a system normally used by AAs)
    • Active transport: amino acids
    • Diffusion: lipophilic things (eg drugs)
    • Active ion exchange
  9. Where BBB is absent
    • Circumventricular organs eg pineal gland (sensory/receptive)
    • Choroid plexus
    • Neurological disorders
  10. CSF found in
    • ventricles
    • central canal of spinal cord
    • subarachnoid space
    • cisterns (Expansions of subarachnoid space)
  11. Function of CSF
    • cushion brain against trauma
    • removes harmful metabolites from ECF
  12. Volume of CSF
  13. Choroid plexus present in
    lateral, 3rd, 4th ventricles
  14. How much CSF secreted per day
  15. Choroid epithelium formed by
    • pia mater (surrounding blood vessels)
    • ependyma (lining ventricles)
  16. Transport across choroid epithelium
    • similar to BBB (tight junctions)
    • specialised transport mechanisms eg facilitated diffusion, ion exchange, active transport
    • 'Blood-CSF barrier'
  17. 4 differences between blood and CSF
    • 1. much less protein in CSF
    • 2. small numbers of lymphocytes in CSF
    • 3. no RBCs in CSF
    • 4. CSF has half the [glucose] found in blood
  18. Eg of when CSF content changes
    bacterial meningitis - becomes cloudy, contains more protein and RBCs
  19. How much CSF is removed per day? How?
    ~400ml via arachnoid villi in arachnoid mater in dural sinuses
  20. Blood drainage in brain
    • superficial cerebral veins in white matter and cortex ? sup/inf sagittal sinuses ? straight sinus
    • deep veins (basal ganglia and diencephalon) ? great cerebral vein ? straight sinus