Flashcards in 10. CSF, BBB, ICP Deck (28)
How much CSF is found in the sub-arachnoid space?
How much CSF is found in the ventricles?
What are the functions of CSF?
Allows brain to exist in neutral buoyancy
Where is CSF produced?
Around blood vessels and along ventricular walls
What is the structure of the choroid plexus?
2 cells thick: endothelial cells of capillary wall and ependema
Tight junctions in ependyma
What are the functions of the tight junctions in the ependyma?
Seals capillary walls to prevent unwanted substances entering CSF
Impermeable to water-soluble solutes, permeable to lipid soluble (these can dissolve in the cell membranes)
Dependable on transporters for water soluble
What is the difference in composition between the CSF and plasma?
more Na+ and Cl-
Less K+ and glucose
What forms the blood-CSF barrier?
Other brain capillaries
What vertebral level is a lumbar puncture needle inserted into?
L3/4 or L4/5
What colour is CSF normally?
What colour is CSF in a sub-arachnoid haemorrhage?
What is the difference in a CSF sample from a patient with meningitis?
What is the difference in a CSF sample from a patient with multiple sclerosis?
Associated antibodies present
What is normal CSF/intercranial pressure?
What is hydrocephalus?
Abnormal accumulation of CSF due to excessive production, obstruction in circulation or faulty reabsorption
Ventricles enlarge and brain is flattened against the skull
What conditions are associated with hydrocephalus?
What are common causes of infantile hydrocephalus?
Stenosis or inflammation of aqueduct of sylvius
What are common causes of adult hydrocephalus?
Obstruction of aqueduct
Obstruction of outflow from 4th ventricle
What is a contracoup injury?
Brain is driven against the opposite side of the skull to where a blow hits
What is a depressed skull fracture?
Bone is driven into brain tissue
What is the blood brain barrier made up of?
Walls of cerebral capillaries
How do brain capillaries differ to peripheral capillaries?
Lower permeability to water and impermeable to solutes due to BBB
In what case is the BBB often absent?
In blood vessels associated with tumours
Plasma proteins will enter ICF of brain tumours
What is the Monroe-Kellie doctrine?
Brain, brain fluid, blood and CSF are all incompressible
ICP is directly related to the volume of these contents
What are the symptoms of increased intercranial pressure?
Headache, nausea, restlessness
What is papilloedema?
Swelling of the optic disc
What triggers Cushing's reflex?
Brain is severely hypercapnic and hypoxic
Triggers vasomotor centre in medulla