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Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
Y2 s1 csf
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Y2 s1 csf

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  • 1. cerebrospinal fluid (CSF) Prof. Vajira Weerasinghe Dept of Physiology
  • 2. cerebral blood flow
    • 750 ml/min (15% of cardiac output)
  • 3. cerebrospinal fluid
    • The cavity enclosing the brain & spinal cord, and the central canal: filled with CSF
    • This fluid is in
      • ventricles
      • cisterns
      • subarachnoid space
      • central canal
  • 4.  
  • 5. cushioning function
    • brain is floating in the fluid
    • this provides a protective function
  • 6. contrecoup injury
    • when there is a severe blow on the head
    • brain is lushed so that the opposite side is struk on the skull to cause an injury
  • 7.
    • volume of CSF
      • 150 ml
    • rate of production
      • 500 ml/day
    • formed
      • mainly in the choroid plexuses of the ventricles
      • small amounts in the ventricles, arachnoid membranes & perivascular spaces
  • 8.  
  • 9. formation
    • choroid plexus projects into
      • horn of lateral ventricle
      • posterior portion of 3rd ventricle
      • roof of the 4th ventricle
    • Mechanism:
      • active transport of Na through the epithelial cells, Cl follows passively
      • osmotic outflow of water
      • glucose moves in to CSF
      • K and HCO3 moved out of CSF
  • 10. absorption
    • arachnoid villi in the walls of venous sinuses
  • 11. circulation
    • fluid secreted in the lateral ventricles into the 3rd ventricle (secretes here)
    • pass along the aqueduct of Sylvius into the 4th ventricle
    • through foramina of Luschka & Magendie into the cisterna magna (behind the medulla)
    • subarachnoid spaces around the brain & spinal cord
    • arachnoid villi in the venous sinuses
  • 12.  
  • 13.  
  • 14.  
  • 15. composition
    • similar to plasma
          • CSF Plasma
          • Na 147 (similar) 150 mmol/l
          • K 2.9 (less) 4.6 mmol/l
          • HCO3 25 24.8 mmol/l
          • Cl 113 (more) 99 mmol/l
          • Pco2 50 40 mmHg
          • pH 7.33 7.4
          • osmolality 289 (similar) 289 mosm
          • protein 20 (less) 6000 mg/dl
          • glucose 64 (less) 100 mg/dl
          • urea 12 (less) 15 mg/dl
    • some substances do not pass into CSF
  • 16. blood brain barrier
    • tight junctions between capillary endothelial cells & epithelial cells in the choroid prevent some substances entering CSF
    • small molecules & lipid soluble substances pass through easily
    • blood-brain barrier exists between blood & brain tissue
    • blood-CSF barrier is present in choroid
    • these barriers are
      • highly permeable to water, CO 2 , O 2 , lipid soluble substances (such as alcohol), most anaesthetics,
      • slightly permeable to electrolytes
      • impermeable to proteins, large organic molecules
      • drugs (variable)
  • 17. Blood brain barrier
  • 18. blood brain barrier
        • CO 2 & O 2 crosses easily
        • H+ & HCO3- slow penetration
        • glucose
          • passive: slow penetration
          • active transport system by glucose transporter GLUT
        • Na-K-Cl transporter
        • transporters for other substances
  • 19. blood brain barrier
      • No blood brain barrier in the hypothalamus & posterior pituitary
        • substances diffuses easily
        • these areas contain chemoreceptors for various substances to detect changes in conc
  • 20. CSF pressure
    • lumbar CSF pressure: 70-180 mmH 2 O
    • this is regulated by absorption through arachnoid villi
    • rate of CSF formation is constant
  • 21. CSF pressure rises
      • if the arachnoid villi are blocked by a disease process
      • brain tumour may compresses the brain and blocks the absorption
      • haemorrhage into the brain tissue can block small channels in the arachnoid villi
      • babies are born with high CSF (as in hydrocephalus) due to a defect before birth
        • blocking the aqueduct of Sylvius
        • blocking of arachnoid villi
  • 22.  
  • 23.  
  • 24.  
  • 25. cerebral oedema
      • because brain is enclosed in a solid cranial vault, accumulation of fluid compresses brain tissue and have serious effects
      • happens due to increased capillary pressure or damage to the capillaries
      • causes
        • compresses vasculature, decreases blood flow, brain ischaemia, arteriolar dilatation, increased capillary pressure, oedema worsens
        • decreases blood flow, deceases oxygen supply, increases capillary permeability, more fluid leakage
  • 26. Cerebral oedema
    • A 45-year-old man was brought to the emergency department by his friends
    • because of a 1-day history of a severe headache and "bizarre behavior.“
    • CT scan of his brain revealed
      • acute intracranial hemorrhage
      • with cerebral edema
      • evidence of midline shift
      • increased intracranial pressure
    • The patient was admitted to the intensive care unit (ICU)
    • young patient
    • was found belatedly after a collapse
    • secondary to drug overdose
    • Note the extensive cerebral oedema
    • with loss of normal grey-white matter differentiation.
    • The patient never regained consciousness
    • eventually died with increased intracranial pressure.
  • 27. brain metabolism
    • brain metabolism is 15% of total metabolism of the body (although brain mass is 2% of total body mass)
    • therefore brain has an increased metabolic rate
    • this is due to increased activity of neurons (AP)
    • requires oxygen
    • brain is not capable of anaerobic metabolism
    • energy supply is by glucose
    • glucose entry is not controlled by insulin
  • 28. Lumbar puncture
    • This is the method of obtaining access to the subarachnoid space This is done for the following purposes
      • To obtain CSF for examination
      • To estimate CSF pressure
    • Patient lying on one side
    • LP needle is inserted between 3 rd and 4 th or 4 th and 5 th lumbar spinous processes
    • Fluid is withdrawn
    • Manometer is connected and pressure measured
  • 29. Lumbar puncture

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