CSF Flashcards
where is CSF formed?
formed by certain brain capillaries and their associated membranes - formation inovlves active transport AND passive diffusion across capillary walls
*Choroid plexus and lateral ventricles*
Where is CSF found in the meninges?
It fills the sub-arachnoid space a- it also fills the ventricles
what is the function of CSF?
it provides support/cushion for the brain
- strictly regulates the external environment for the nuerons/ganglia
- distributes hormones in the CNS
- major route for removing harmful brain metabolites
?what is a contrecoup injury?
When brain is driven against skull following severe blow to opposite side of skull.
what are choroid plexi? What are the responsible for?
they are formed by tufts of capillaries and their associated membranes which invaginate into the lateral, third and fourth ventricles= forms 70% of CSF
what are the two layers of the choroid plexus?
Endothelial cells of capilary wall
ependymal cells surroudning the capillary called the ependyma- which act as a continual sheath of tissue covering and sealing the capillary wall - restricting movement of things from blood to CSF
what sort of junction is between the choroid plexus epithelial cells?
they are connected by tight junctions- ependyma therefore acts as a continous sheath of tissue covering and sealing the capillary wall - this restricts free movment of substances from blood into CSF
what sort of molecules cnanot pass the choroid plexus?
they have very low permeability to lipid-insoluble solutes like ions, glucose, amino acids setc -
movement across the choroid plexus depends on what?
presence of transporters in the
walls of the ependyma (e.g. Glucose Transporter GLUT1)
how does the CSF differ from plasma?
it is mainly different in proteins, plasma has MUCH more protein than CSF - so if they take a sample of CSF and there are lots of proteins present then it’s indicative that somethings wrong
Slightly more acidic than blood
where do you insert a needle for a lumbar puncture?
a hollow needle is inserted between 3rd anf 4th or 4th and 5th vertebrae b/c the spinal cord ends at L1-2
what should you see in a normal CSF sample?
clear colorless fluid, no WBCs, no RBCs (injury), little protein, and 70% glucose
How much CSF do we have?
140 ml - not much but it’s always constant (absorbed/produced balanced- flows thorugh CNS)
23 mls are in the ventricles and 117 ml are in the subarachnoid space
where does the majority of the CSF get reabsorbed?
in the arachnoid Villi
what might lead to increased CSF pressure?
an obstruction to the circulation of the CSF, too much production, not enough reabsorption
Is the blood CSF barrier the same as the blood brain barrier?
They are differnet, but they have the same function - to keep things out of the CSF
