The characteristics & composition of CSF Appearance Clear & colorless Volume 130ml ...
The characteristics & composition of CSF
| Appearance | Clear & colorless |
| Volume | 130ml |
| Rate of production | 0.5ml/ min (Production of CSF is not pressure regulated, keep on producing even the reabsorption is obstructed) |
| Pressure (Spinal tap with patient in lateral recumbent position) | 60 – 150 mmH2O Constant, but can increase in: Straining Laughing Coughing Sneezing Compressing IJV of the neck) |
| Composition | |
| Protein | 15 – 45mg/ 100ml |
| Glucose | 50 – 85mg/ 100ml (CSF Glucose </ = 2/3 of blood glucose) |
| Cl– | 720 – 750mg/ 100ml |
| Number of cells | 0 – 3 Lymphocytes/ mm3 |
| Formation | Mainly in the choroid plexus & little amount from ependymal cells |
| Circulation | Circulation is aided within the skull by: Arterial pulsation of the choroid Cilia on the ependymal cells In the spinal canal, it’s aided by: Pulsation of spinal arteries Movements of the vertebral column Respiration Coughing Changing of the body position |
| Absorption | The main site is arachnoid granulations (They increase in size & number and tend to become calcified with advancing age) Absorption : CSF pressure > Venous pressure Prevents reflux of blood when Venous pressure > CSF pressure (Arachnoid villi serves as valves) Rate of absorption controls the CSF pressure |
The functions of CSF
1) Cushions & protects CNS from trauma
2) Provides mechanical floating (Buoyancy) & support to brain
3) Serves as a reservoir & assists in the regulation of the content of the skull
4) Nourishes the CNS
5) Removes metabolites from the CNS
6) Serves as a pathway for pineal secretions to reach the pituitary gland
Blood brain barrier
1) It’s formed by tight junctions between the endothelial cells of the blood capillaries
2) Non lipid soluble or water soluble substances cannot cross the BBB
Drugs which cannot cross the BBB
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Drugs which can cross the BBB
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