Physiology: CSF Production and Circulation Flashcards
describe what cerebrospinal fluid(CSF) is and what is it produced by
clear, colourless liquid composed mostly of water
produced by secretory epithelium of the choroid plexus
what volume of CSF circulates and how often is it replaced
around 150ml, replaced 3-4 times a day
what are the 3 major functions of CSF
mechanical protection, homeostatic function, circulation
describe the mechanical protection function of the CSF
shock-absorbing medium that protects brain tissue, brain “floats” inside cranial cavity
describe the homeostatic function of of the CSF
pH of CSF affects pulmonary ventilation and cerebral blood flow, also transports hormones
describe the circulatory function of the CSF
medium for minor exchange of nutrients(eg water, ions, amino acids) and waste(eg metabolites) products between blood and brain barrier
where is the choroid plexus found, in the adult brain
in the 3rd, 4th and lateral ventricles
describe the involvement of ions in the secretion of CSF
CSF secretion involves transport of ions(Na, Cl and HCO3) across the epithelium from blood to CSF
where does CSF formed by choroid plexus in the lateral ventricles flow
flows to 3rd ventricle through 2 narrow openings called the interventricular foramina
what happens to CSF in the 3rd ventricle and where does it flow to from there
more CSF added by choroid plexus in roof of 3rd ventricle, then flow through aqueduct of midbrain(cerebral aqueduct) and into the 4th ventricle
what happens to CSF in the 4th ventricle and where does it flow to from there
more CSF added, then enters the subarachnoid space through 3 openings in 4th ventricle roof, then circulates in canal of spinal cord
how does CSF return to venous blood
through arachnoid granulations into the superior sagittal sinus(SSS)
what is the function of the blood-CSF and blood-brain barriers
to stop free exchange of ions/bacteria etc between them
