MENINGES, CEREBROSPINAL FLUID AND BLOOD BRAIN BARRIER

1. DR NILESH KATE
MBBS,MD
ASSOCIATE PROF
ESIC MEDICAL COLLEGE, GULBARGA.
DEPT. OF PHYSIOLOGY
MENINGES,
CEREBREOSPINAL
FLUID AND BLOOD
BRAIN BARRIER.

2. OBJECTIVES.
 Meninges.
 Cerebrospinal fluid.
 Blood brain barrier
 Blood –CSF barrier
 Cerebral blood flow.

3. MENINGES.
 Pia Mater – Covering
External Surface Of
Brain, Thin, Vascular.
 Encloses tuft of
capillaries choroid
plexuses to form Tela
choroidea
Wednesday, April 25, 2018

4. MENINGES.
 Arachnoid Mater –
connected to Pia
mater by filamentous
fibers.
 Subarachnoid space is
filled with CSF.
Wednesday, April 25, 2018

5. MENINGES.
 Dura Mater
 Composed of 2 layers: outer
Endosteal & inner
Meningeal.
 Folds of this forms Falx
cerebri & venous sinuses
between them.
 Arachnoid villi pass through
Dura mater & project into
venous sinuses to escape
CSF.
Wednesday, April 25, 2018

6. CEREBROSPINAL FLUID.
 Cushions the brain
 With BBB buffer
function of neuroglia &
regulate CNS
circulation.
Wednesday, April 25, 2018

7. COMPOSITION OF CSF
Constituents Lumbar CSF BLOOD
Na (mEq/L) 148 136-145
K (mEq/L) 2.9 3.5-5
Ca (mEq/L) 2.3 4.7
Cl-(mEq/L) 120-130 100-106
HCO3 (mEq/L) 25.1 24.8
Glucose (mEq/L) 50-75 70-100
protein(mEq/L) 15-45 6.8 × 103
pH 7.3 7.4
Osmolality 289 289
Wednesday, April 25, 2018

8. CSF VOLUME AND PRESSURE
 Cranial cavity contains
 140 ml CSF (100 ml in subarachnoid
space & 40 ml in ventricles)
 100 ml blood
 200 ml ECF.
 Wt – 1350 gm.
 ECF space – 440 ml
 Pressure – 120-180 mm of H2O
 Rate of CSF formation – 0.35
ml/min.
Wednesday, April 25, 2018

9. FORMATION OF CSF
 Mainly from Choroidal
plexus covered by
ependymal cells.
 Site – cerebral
ventricles
 Rate – 500 ml/day.
Wednesday, April 25, 2018

10. CIRCULATION OF CSF.
 Lateral ventricle
Foramina of
Monro
 Third ventricle
 Cerebral aqueduct of sylvius.
 Fourth ventricle
 Central canal of spinal cord
& subarachnoid space.
Wednesday, April 25, 2018

11. ABSORPTION OF CSF.
 80% removed by
valvular Arachnoid
villi into Dural venous
sinuses.
 20% pass along sheath
of cranial nerves into
cervical Lymphatics &
perivascular spaces.
Wednesday, April 25, 2018

12. FUNCTIONS OF CSF.
 Water Jacket – as absorbs shock.
 Removal of waste products of brain metabolism
 Regulates EC environments for neurons
 Transport hormones & hormones releasing factors.
Wednesday, April 25, 2018

13. CLINICAL APLLICATION.
 Hydrocephalus – abnormal
accumulation of CSF in
cranium.
 Causes
 Obstruction of CSF
circulation.
 Excessive production of CSF.
 Interference with absorption
of CSF.
Wednesday, April 25, 2018

14. TYPES OF HYDROCEPHALUS.
 Internal or non-
communicating – When
obstruction is within the
ventricular system or in
the roof of fourth ventricle
 External or
communicating –
obstruction is in
subarachnoid space or
arachnoid villi
Wednesday, April 25, 2018

15. LUMBAR AND CYSTERNAL
PUNCTURE
 Lumbar puncture.
 Tapping of CSF from lumbar cistern.
 For CSF examination
 Between L2-L3 or L3-L4
 Cisternal puncture.
 Tapping of CSF from Cisterna
Magna.
 Through posterior atlanto-occipital
membrane forward & upward.
Wednesday, April 25, 2018

16. MEASUREMENT OF CSF
PRESSURE.
 During lumbar
puncture
 Needle connected to
glass tube & CSF
allowed to rise
 Level of fluid above
spinal needle gives
pressure in cm of H2O
Wednesday, April 25, 2018

17. BLOOD BRAIN BARRIER
 Restrict movements of
large molecules &
highly charged ions
from blood into brain
& spinal cord.
 Formed by CNS
capillary endothelial
cells, intercellular
junctions
Wednesday, April 25, 2018

18. AREAS WITHOUT BBB
 Posterior Pituitary
gland.
 Circumventricular
organs.
Wednesday, April 25, 2018

19. DISRUPTION OF BBB
 In Brain tumors
 Bacterial meningitis.
Wednesday, April 25, 2018

20. BLOOD –CSF BARRIER
 It exists at the level of
epithelial cells that
make up the choroid
plexus.
 Responsible for
carrier mediated
active transport.
Wednesday, April 25, 2018

21. CEREBRAL BLOOD FLOW.
 Functioning of brain
– total function of
brain ceases after
complete stoppage of
blood supply within 5-
10 sec.
 Due to decrease in
oxygen delivery &
cessation of metabolic
activity.
Wednesday, April 25, 2018

22. NORMAL CEREBRAL BLOOD
FLOW
 50-65 ML/100 gm i.e. 750-900 ml/min
 15 % Of Cardiac output.
Wednesday, April 25, 2018