BBB and CSF

special characteristics of brain capillaries

interendothelial tight junctions and astrocyte end feet ensure less leaks out

how do things pass through the blood brain barrier

interendothelial tight junction active gates, transport mechanisms

things that are transported across the BBB

ions, peptides, glucose

regions without a BBB

pituitary gland, periventricular organs, pineal gland (for endocrine functioning)

functions of the BBB

maintain intracerebral environment free of chemical factors, maintain homeostasis, protect from rapid fluctuation in ion concentrations

cause of disruption of the BBB

tumors, inflammatory disorders, bacterial meningitis

consequence of a disruption of the BBB

perivascular edema

location of dural venous sinuses

between the outer and inner layers of the dura mater

function of dural venous sinuses

drains blood from cerebral veins, CSF from subarachnoid space

where do the dural venous sinuses dump into

internal jugular vein

how the dural venous sinuses differ from veins

no valves or muscular coat

function of arachnoid villi

allow CSF to leave the subarachnoid space and enter the blood stream via the sinuses

names of dural venous sinuses

superior sagittal, inferior sagittal, straight, transverse, cavernous, sigmoid

dural sinus thrombosis

clot in a sinus or cerebral veins

effects of a dural sinus thrombosis

decreased venous flow, increased pressure, dilation of cerebral veins, decreased perfusion, hypoxic tissue damage

signs of dural sinus thrombosis

thunderclap headache, nausea/vomiting, seizure, altered mental status

ventricles of the brain

lateral, third, fourth

interventricular foramen

communication between the lateral ventricles

cerebral aqueduct (of sylvius)

communication between the third and fourth ventricles

lateral and median apertures

foramina in the fourth ventricle that communicate with the subarachnoid space

function of the ventricles

contain the CSF created by the choroid plexus

mechanism of CSF movement through the ventricular system

ependymal cells line the ventricles and fluctuation in volume causes the cilia to beat and move the CSF

path of flow of CSF

lateral ventricles → third ventricle → fourth ventricle → median/lateral apertures → subarachnoid space → rostral: arachnoid villi, caudal: spinal subarachnoid space

functions of the CSF

cushion during rapid head movements, removal of brain metabolites, protects from fluctuations in blood

normal intracranial pressure

5-15 mmHg

hydrocephalus

increased intracranial pressure

potential causes of hydrocephalus

increased CSF secretion, reduced resorption, obstruction (tumor, infection, hemorrhage)