CSF and BBB Flashcards
What cells make the outer and inner layer of the arachnoid mater?
Outer= barrier Inner= trabecular
Name the 3 forms of cerebral haemorrhage?
Outside dura= epidural
Between dura and arachnoid= subdural haemorrhage
Inside arachnoid space= subarachnoid
Signs/ symptoms of epidural haemorrhage?
Arterial usually
No initial symptoms, but then severe headache as haematoma compresses brain
Signs/ symptoms of subdural haemorrhage?
Occurs in bridging veins, so onset symptoms slow.
Imaging shows blood spread diffusely across brain surface
Signs/ symptoms of subarachnoid haemorrhage?
Ruptured aneurysm
Sudden, sevvere headache
How does epidural bleed occur in MRI?
Lens shaped
What is meant by lucid interval?
In epidural bleed, patients may regain consciousness briefly only to descend into unconciousness again
What is the falx?
Where the dura descends down between hemispheres, dividing them and forming a sheet (falx)
Where does the falx make a T junction with occipital dura?
At occipital pole
What are the tentoria?
Pair of transvere sheets of dura extending laterally below base of occipital cerebelum
What do you call the gap between the two tentorii?
Tentorial incisure
What passes through the tentorial incisure?
Brainstem
What are the four ventricles of the brain
Lateral ventricles (1&2)
Third ventricle
Fourth ventricle
What forms CSF?
Choroid process
What is the choroid process?
Meshwork of capillaries covered by ependymal cells protruding into the ventricles of the brain
Which ventricle contains majority of choroid process
Lateral ventricles
Why do small changes in blood pCO2 cause large changes into csf pH?
Healthy CSF contains little protein and no cells so is not pH buffered in the same way as blood
At what rate is CSF produced?
500ml/day
How much CSF is held in the brain?
135-150ml/day
How is CSF drained from the lateral ventricles into the blood?
From lateral to 3rd and 4th to cisterna magna to subarachnoid space
Absorbed into arachnoid granulations and joins venous blood in superior sagittal sinus
What is hydrocephalus?
Accumulation of CSF in the ventricular system
What causes hydrocephalus?
obstruction of normal CSF circulation with consequent dilation of ventricles
usually due to blockage in cerebral aqueduct
3 main functions of astrocytes
maintain local pH and glucose
remove excess NT, metabolites
secrete growth factors/ cytokines
How do astrocytes respond to CNS injury?
Proliferate to form astrocytic site
Proper names of grey matter and white matter astrocytes
Grey: protoplasmic astrocytes
White: Fibrous astrocytes
What are end feet?
The processes of astrocytes end in expansions called end feet
Function of tight junctions in brain capillaries
Prevent exit of proteins
What makes up the blood brain barrier?
Astrocyte end feet and tight junction system
Where do arachnoid granulations penetrate the dura?
At the top of the brain
What is the superior sagittal sinus
Vein running sagitally along midline
What veins run into the skull
Diploid
What is a common cause of epilepsy?
Malfunction of the glial cells in region where an infract or other neuronal insult has occured
What molecules can pass the blood brain barrier unaided?
Lipid-soluble molecules such as opiates
