1. Cerebrospinal fluid & the blood-brain barrier
Fluids of the CNS
Cerebrospinal fluid & the blood-brain barrier

2. Meninges Membranous coverings of the CNS Layer of 3 tissues
Protects nervous tissue and provides support and cushion

3. Meningitis
Bacterial meningitis results when a bacterial infection of the meninges
Produces increased cranial pressure
May produce seizures & unconsciousness

4. Cerebrospinal fluid (CSF)
In the space between the middle meninge & that closest to the CNS tissue
Circulates through the ventricles & to the brainstem
CSF allows the CNS to float in a cushion of fluid
Provides shock absorption

5. Nutrients for the CNS
The CSF provides nutrients & energy and acts to eliminate waste.
Glucose is the brain’s only energy source..
O2 is required cellular respiration
Brain receives 12-15% of the total blood supply.
Brain injury - most commonly results from depleted O2 supply.

6. Blood-brain barrier
Group of mechanisms that regulate the flow of chemicals between CSF & the blood.
blocks/decreases entry of toxins.
few chemicals/molecules are allowed to pass through.
Immune system molecules have limited access
Mostly Lipid molecules

7. Ease of passage Lipid soluble substances pass through more easily.
Water soluble substances pass through slowly & can linger in the fluid.

8. Membrane transport proteins
Allows substances that are NOT lipid soluble to pass in & out of the barrier.
Move required substances in, like glucose.
Move waste out.