Cerebrospinal fluid (CSF) is a clear, colorless fluid that surrounds the brain and spinal cord, produced by the choroid plexus at a rate of approximately 0.3 ml/min, with an average volume of 150 ml. CSF acts as a buffer, protects the brain from trauma, and facilitates the exchange of nutrients and waste products between blood and brain tissue, with a complex absorption process primarily occurring through arachnoid villi. Abnormalities in CSF accumulation can lead to conditions such as hydrocephalus, which presents with symptoms such as headache, vomiting, mental weakness, and gait instability.

1. Submitted by
Iqra Rubab

2.  CSF is clear, colorless and transparent
 Circulates through cavity of the:
 –Brain
 –Subarachnoid space
 –Central canal of spinal cord
 •Part of Extracellular fluid (ECF)

3. • Volume : approximately 150 mL
• Rate of formation: approximately 0.3 mL/min
• Specific gravity : 1.005
• Reaction : Alkaline

4.  Water =99.13%
 Solid =0.87%
Organic substance:
1. Protein
2. Amino acid
3. Sugar
4. Urea
5. Uric acid
6. Creatinine
7. Lactic acid
8. cholesterol
Inorganic substances
1. Sodium
2. Calcium
3. Potassium
4. Magnesium
5. Bicarbonate
6. Sulfhate
7. Chlorides
8. Phosphate

5.  As CSF is part of ECF therefore it contain more amount of Sodium than Potassium.
 Contains some lymphocytes.
 CSF secreted by ventricles does not contain any cell.
 The lymphocytes are added when it flows in the spinal co

6.  • Site of formation
 – Formed by the choroid plexus situated within the
 ventricles.
 – The choroid plexus are tuft of capillary projections present
 inside ventricles and covered by:
 • Pia mater
 • Ependymal covering

7.  Formed by process of secretion.
 Does not involve ultrafiltration or dialysis.
 Uses energy.
 Active transport mechanism is involved in secretion.

8.  Pilocarpine, ether and extracts of pituitary gland stimulates the secretion of CSF
by stimulating choroid plexus.
 Injection of isotonic saline also stimulates CSF formation.
 Injection of hypotonic saline
1. Causes greater rise in capillary pressure and intracranial pressure,
2. Fall in osmotic pressure leading to increase in CSF formation.
 Hypertonic saline
 Decreases CSF formation
 Decreases CSF pressure

9. Formation of CSF in lateral ventricles
Foramen of Monro
Third ventricle
Aqueducts Sylvius
Fourth ventricle
Foramen of magendie and foramen of Luschka
Cisterna magna and Cisterna lateralis
Subarachnoid spaces
To the spinal cord
To cerebral hemispheres

10.  Mostly absorbed by the Arachnoid villi into Dural sinuses and Spinal veins.
 Small amount is absorbed along the perineural spaces into cervical lymphatics and in to the perivascular spaces.
 Normally, 500 mL of CSF is formed everyday and equal amount is absorbed.
•By filtration due to pressure gradient between hydrostatic pressure in the subarachnoid space fluid
•And the pressure that exists in the Dural sinus blood.
•The colloidal substances pass slowly and crystalloids are absorbed rapidly.

11.  • Varies in different position:
 Lateral recumbent position = 10-18 cm of H2O
 Lying position = 13 cm of H2O
 Sitting position = 30 cm of H2O
 Coughing and crying increases the pressure by decreasing the absorption.
 Compression of internal jugular vein also raises the CSF pressure

12. 1. Acts as buffer
2. Protects the brain from shock
3. If brain receives severe blow , countercoup injury may take place.

 Is very essential because
 When substances are absorbed into the venous sinuses, intracranial pressure is raised,
 Intracranial pressure in turn interferes with the cerebral circulation causing Asphyxia.
 It is prevented by greater absorption of CSF to give space for increasing cranial contents.

13.  CSF is the medium through which substances like :
 Nutritive substances
 Waste materials are exchanged between blood and brain tissues.

 Collected by :
 – Cisternal puncture or
 – Lumbar puncture
 • In Cisternal puncture
 –CSF is collected by passing needle between Occipital bone and Atlas, so it enters the cisterna
magna.

14.  The Lumbar puncture needle is introduced into the subarachnoid space in the Lumbar region ,
between the third and fourth Lumbar spines.
 Uses of Lumbar puncture
 Collecting CSF for diagnostic purpose.
 Injecting drugs for spinal anesthesia, analgesia and chemotherapy.
 Measuring pressure exerted by CSF.

 Barrier between the blood and cerebrospinal fluid .
 Exists at the Choroid plexus.
 Similar to Blood-Brain Barrier(BBB)
 Allows the movement of only those substances, which are allowed by BBB

15.  Oxygen
 Carbon dioxide
 Water
 Glucose
 Amino acids
 Electrolytes
 Drugs such as L-dopa, 5-hydroxytryptamine sulfonamides, tetracycline and other lipid soluble
drugs
 Anesthetic gases such as ether, nitrous oxide which are lipid soluble
 Other lipid soluble substances.

16.  Injurious chemical agents.
 Pathogens such as bacteria.
 Drugs such as Penicillin and the Catecholamines.
 Dopamine also can’t pass therefore Parkinsonism is treated with L-dopa instead of
dopamine.
 Bile pigments
 However barrier is not well developed in infants.
 The bile pigments enter the brain tissues .
 During jaundice in infants, the bile pigments enter the brain and causes damage
of Basal ganglia leading to Kernicterus.

17.  Hydrocephalus
 Abnormal accumulation of CSF in the skull with enlargement of head.
 2 types of Hydrocephalus
1.non-communicating
2.communicating
 Non-communicating Hydrocephalus or Internal Hydrocephalus
 Due to the obstruction of any of the foramen through which CSF escapes results in
dilation of ventricular cavity.
 Communicating Hydrocephalus or External Hydrocephalus
 Due to blockage of Arachnoid villi.

18.  Symptoms of Hydrocephalus:
 Headache
 Vomiting
 Atrophy of brain
 Mental weakness
 Convulsions
 Normal pressure Hydrocephalus
 – Same as Communicating Hydrocephalus but it is due to decreased CSF absorption.
 • Symptoms :
 Gait instabiltiy
 Urinary incontinence
 Dementia