Module Exam 6: Cerebral Circulation Flashcards
Posterior Circulation is from the
Basilar Artery
Anterior Circulation is from the
Internal Carotid Artery
Joins the two Anterior Cerebral Arteries
Anterior Communicating Artery
Joins the Internal Carotid Artery with the Basilar circulation
Posterior Communicating Artery
Normally communicating arteries have little _____ unless occlusion in one artery occurs.
Blood flow
Circle of Willis variants: the complete circle is seen in only ______ of individuals.
20-25%
Circle of Willis variants: one or both _______ are hypoplastic in ____.
Posterior Communicating Artery. 34%.
Circle of Willis variants: The _____________ may be absent or hypoplastic in _____.
Precommunicating segment of ACA (A1). 25%.
Circle of Willis variants: bilateral hypoplastic ___ segments in ___.
P1. 11%.
________ drain into dural venous sinuses which eventually empty into the _____.
Cerebral veins. IJV.
Dural venous sinuses
Superio sagittal sinus, Inferior sagittal sinus, Transverse sinus, Sigmoid sinus, Cavernous sinus & Straight sinus “SITS CS”
Major cerebral veins
Basal vein of Rosenthal, Internal cerebral vein & Great cerebral vein of Galen “BIG”
In 1981, Lumbar puncture was introduced by
Quincke
In 1912, he made the first correlations between disease processes and the cellular and chemical changes in the CSF.
Mestrezat
In 1937, they published their classic monograph on the CSF changes in all types of disease.
Merritt & Fremont-Smith
In 1950s, this technique were introduced
Membrane filtration
Their studies provide the basis of our knowledge of CSF formation, circulation and absorption. Pappenheimer, Ames, Fishman & Davson.
Dandy & Weed
Total CSF volume in the adult is
150mL
Total CSF volume in the subarachnoid space is
30mL
About how many volume of CSF fluid is produce per day
500 mL
Helps to preserve a stable chemical environment for neurons and their myelinated fibers. Act as a mechanical support and it removes the wast products of cerebral metabolism.
CSF
CSF provides ______ for the brain and SC. Provides ______ to the brain.
Water jacket. Buoyancy.
Waste products removed by CSF
CO2, Lactase & Hydrogen ion
Average rate of CSF formation is
21-22mL/h (0.35mL/min)
The CSF is therefore renewed _______ daily.
4x or 5x
Main sites of CSF formation
Choroid plexuses
Choroid plexuses are located in the
Floor of lateral, third and fourth ventricles
In CSF formation, The thin walled vessels of the plexuses allow _______ of substances from the blood plasma into the extracellular space surrounding choroid cells.
Passive diffusion
In CSF formation, Electrolytes equilibrate with the CSF at all points in the _______ and _________. The same is true of ______. The transport of sodium is accomplished by the action of a _________ exchange pump at the apical surface of the choroid plexus cells.
Ventricular & Subarachnoid spaces. Glucose. Sodium potassium ion exchange.
In CSF formation, it is also known that the penetration of certain drugs and metabolites is in direct relation to their ________. Ionized compound such as _______ & ___, being relatively insoluble in lipids, enter the CSF slowly unless facilitated by a membrane transport system.
Lipid solubility. Hexoses & AAs.
Is a collective term for all barriers lying between the plasma and the neuropil.
Blood Brain Barrier
BBB is formed by the tight junction, _________, of capillary endothelial cells.
Zonula occludens
Physiologically, the system of barriers enables the regulation of the ______ of brain tissue and CSF and the ____ & _______.
Osmolarity. ICP & volume.
Is permeable to water soluble substances but not to lipo-soluble substances such as anesthetics, psycho active drugs and analgesics.
Blood CSF barrier
Is generally permeable to liposoluble substances (of molecular weight less than ______) but not to water soluble substances.
Blood Brain Barrier. 500 daltons.
Specialized areas without BBB
Vascular organ of the lamina terminalis, Median eminence, Area postrema, Pineal body, Posterior pituitary & Subfornicial organ “VMAPPS”
The fluid filled cerebral ventricles constitute the
Inner CSF space