3. CSF
C.S.F LOCATION
Ventricles of brain
Cisterns around outside of brain
Subarachnoid around
Brain
Spinal cord
All these chambers are connected with one
another
Constant pressure
3
9. CSF
COMPOSITION OF CSF
1. GLUCOSE is 30% less (64mg%)
2. Protein. Only 20-25mg% as compared to
7500mg% in plasma
3. Cells. Very few lymphocytes (1-5 cell/mm3)
4. osmotic pressure equal to plasma;
5. sodium ion equal to plasma;
6. chloride ion 15 percent greater than
plasma;
7. potassium ion 40 per cent less;
9
10. CSF
FUNCTIONS OF C.S.F
1. Acts as fluid buffer (cushioning the CNS
against injury)
2. Acts as reservoir to regulate the
contents of the cranium
3. May act as a medium of nutrient
exchange in the CNS; However brain
carries out its metabolic exchanges
directly with blood.
4. Clinical - DIAGNOSTIC
Therapeutic 10
11. CSF
FORMATION OF CSF
Sites:
>2/3 by Choroid plexus
<1/3 by Ependymal surfaces
arachnoidal membrane
perivascular spaces
(A small amount also comes from brain
itself)
Choroid plexus: Cauliflower like growth
of blood vessels covered by thin
epithelium, projecting into all
ventricles
11
19. CSF
ABSORPTION
To the venous system by bulk fluid through
arachnoid granulations, located in the
superior sagital sinus by pressure
gradient.
(Arachnoid villi function like Valves and allow
one-way flow)
Arachnoid granulations :
Projections of arachnoidal membrane in
venous sinuses:- Arachnoid villi (Microscopic)
Collection of Arachnoid villi:- Arachnoidal
Granulations (Macroscopic)
Endothelial cells cover the villi
19
20. CSF
DRAINAGE OF A PERIVASCULAR SPACE
INTO THE SUBARACHNOID SPACE
20
Lymphatic system
24. CSF
AUTOREGULATION OF CBF
Definition of Autoregulation:
The process by which blood flow to the tissues is
maintained at relatively constant level despite
changes in perfusion pressure
Extremely well autoregulated between arterial
pressure limits of 60 and 140 mmHg
In hypertensives, upto 160-180 mmHg
Roll of Sympathetic Nervous System in exercise
Very high mean arterial pressure
Sympathetic stimulation causes vasoconstriction of brain
arteries to prevent vascular hemorrhage
24
26. CSF
CEREBRAL MICROCIRCULATION
Capillaries are much less “leaky”
No fenestrations (few exceptions)
Mechanism: Glial feet by the surrounding
Glial cells surround the capillaries
26
27. CSF
PROTECTIVE MECHANISMS OF
BRAIN
1. Trauma
Skull bones
CSF
2. Blood flow in case of high arterial
pressure
Autoregulation
Sympathetic nervous system e.g. in
exercise
Walls of small arterioles become
thickened to prevent transmission of
high blood pressure to capillaries
27
Contd…..
28. CSF
PROTECTIVE MECHANISMS OF
BRAIN
3. Blood flow in case of low blood
pressure and metabolic disorders
Autoregulation
Roll of CO2, H+ and O2
4. Edema
Tight capillary junctions
5. Protection of brain from endogenous
and exogenous toxins
Blood-CSF and Blood- Brain Barriers
28
29. CSF
DISEASES RELATED TO CSF AND
CEREBRAL BLOOD FLOW
Cerebral stroke
Brain injury
Brain edema
↑CSF Pressure
29
30. CSF
DISEASES RELATED TO CSF AND
CEREBRAL BLOOD FLOW
(CEREBRAL STROKE)
Blockage of cerebral arteries
Rupture of cerebral arteries
30
Contd……..
31. CSF
DISEASES RELATED TO CSF AND
CEREBRAL BLOOD FLOW
(CEREBRAL STROKE)
BLOCKAGE OF CEREBRAL ARTERIES
Old age
Arteriosclerotic plaques
Activation of clotting mechanism
31
Contd……..
32. CSF
DISEASES RELATED TO CSF AND CEREBRAL BLOOD
FLOW
(CEREBRAL STROKE)
RUPTURE OF CEREBRAL ARTERIES
Rupture of cerebral arteries
High blood pressure
Middle cerebral artery
Loss of function in Wernich’s speech comprehension area
Dementia
Loss of function in Broca’s area
Unable to speak
Posterior cerebral artery
Infarction in occipital lobe
Loss of vision on both sides in the half of retina on the same side of
stroke lesion
Damage to blood supply of midbrain
Blockage of nerve conduction in major pathways between brain
and spinal cord
Sensory and motor abnormalities
32
33. CSF
DISEASES RELATED TO CSF AND
CEREBRAL BLOOD FLOW
(BRAIN EDEMA)
When systems for protecting against
transudation of fluid into the brain break down
e.g.
Brain concussion
Blow to head
High blood pressure
Mechanism
↑Capillary Pressure
↑ Damage to capillary walls
Coma and death 33
35. CSF
DISEASES RELATED TO CSF AND
CEREBRAL BLOOD FLOW
(BRAIN INJURY)
Coupe
Damage/injury to the brain on the same side of
trauma
Countercoup
Damage/injury to the brain on the opposite side
of trauma
37
36. CSF
DISEASES RELATED TO CSF AND CEREBRAL BLOOD
FLOW
(↑CSF PRESSURE)
Causes
↑ formation (rare)
↑ number of blood cells or plasma proteins
Hemorrhage
Infection
Blockage of reabsorption
↓reabsorption (Obstruction to outflow)
Fibrosis of villi
Brain tumors
Congenital
Hydrocephalus 38
38. CSF
FECTS OF ↑CSF PRESSURE
Papilledema : Edema of the Optic Disc
(& Retinal edema)
Significance of Papilledema
Clinical diagnosis of ↑CSF Pressure by
ophthalmoscope
Effects of Papilledema
Blindness/ blurred vision
40
39. CSF
EFFECTS OF ↑CSF PRESSURE
Hydrocephalus
Excess water in cranial vault
Types
Communicating
Non-Communicating
Swelling of head in children
Brain damage
41
40. CSF
MEASUREMENT OF CSF PRESSURE
Person lying horizontally on his/ her side so
that pressure in spinal canal = pressure in
cranial vault
Spinal needle is inserted in lumber spinal
canal
Same procedure for composition of CSF
42
41. CSF
BLOOD-CSF AND
BLOOD- BRAIN BARRIERS
Blood- Brain Barrier
Tight junctions between adjacent Endothelial cells
Blood-CSF Barrier
Tight junctions between adjacent Choroid Epithelial
cells
Many large molecular weight substances hardly
pass into CSF or interstitial fluids of brain
These barriers are similar, therefore
Blood-CSF and Blood- Brain
Barriers= Blood- Brain Barrier
43
42. CSF
FUNCTIONS OF BLOOD- BRAIN
BARRIER
1. Maintain constant environment of neurons
• Brain neurons highly sensitive to changes in
ionic concentration
2. Protection of brain from endogenous and
exogenous toxins
3. Prevention of escape of neurotransmitters
into general circulation
44
43. CSF
CLINICAL IMPLICATIONS OF
BLOOD- BRAIN BARRIER
1. Immature at birth → Kernicterus (Entry of free
bilirubin in brain)
2. Some amines (e.g. dopamine and serotonin do not
penetrate brain tissue, so their precursors are
given, i.e. L-Dopa and 5-Hydroxytryptophane)
3. Breakdown of Blood- Brain Barrier in infection or
injury
45
44. CSF
BRAIN METABOLISM
Brain weight= 2% of body weight
Brain metabolism= 15% of body metabolism
(resting, awake)
46
45. CSF
SPECIAL REQUIREMENTS OF BRAIN FOR
OXYGEN
LACK OF SIGNIFICANT ANAEROBIC
METABOLISM
Most tissues of body can live without
Oxygen for many minutes
Anaerobic metabolism
Excessive amounts of glucose and glycogen are
used
Brain is not capable of significant
anaerobic metabolism
Reason:-
High metabolic rate of neurons
Sudden cessation of brain blood flow/ or
total lack of oxygen:-
Unconsciousness within 5-10 minutes 47
46. CSF
BRAIN UTILIZES GLUCOSE AS ENERGY
Brain needs continuous supply of Glucose
Only about 2 minute supply of glucose
normally stored in brain as Glycogen
Almost all energy is derived from glucose
derived from blood
Glucose delivery to brain not dependent
on insulin
Advantage: preventing loss of function in
Diabetes (↓Insulin)
Disadvantage: over-treatment with insulin→
unconsciousness 48