Presentation on theme: "Blood supply to the brain The cerebrospinal fluid (CSF)"— Presentation transcript:
1Blood supply to the brain The cerebrospinal fluid (CSF) Mark Kozsurek, M.D., Ph.D.19/09/2011, EM II.
2Extremly high demand for oxygen and nutrients: human brain represents 2% of the body weight, but receives 15% of the cardiac output, 20% of total body oxygen consumption and 25% of total body glucose utilization.Cerebrovascular deseases and stroke are among the major causes of death.
12Circle of Willis pituitary stalk optic chiasm oculomotor n. abducens n.pituitary stalkoptic chiasmmamillary bodies
13Circle of Willis encloses the optic chiasm, pituitary stalk and mamillary bodies. 2. Oculomotor nerve exits between the post. cerebral and sup. cerebellar arteries.3. Vertebral arteries of the two sides unite to form the basilar artery at the ponto-medullary junction. The root of the abducens nerve and initial segment of the ant. inf. cerebellar artery can also be found here.
29superficial middle cerebral vein superior cerebral veinsSUPERFICIAL VEINSsuperficial middle cerebral veininferior cerebral veinsSimilarly, there are superior and inferior celebellar veins for the cerebellum.
30Superior cerebral veins open into the superior sagittal sinus or into the adjacent lateral lacunae.
311.Inferior cerebral veins drain mainly into the sphenoparietal (1), cavernous (2), superior petrous (3), and transverse (4) sinuses.2.3.4.
37Almost the total volume of veinous blood collected from the brain leaves the skull through the jugular foramen and the internal jugular vein.If the jugular foramen and/or the internal jugular vein is getting occluded, blodd may escape through the diploic and emissary veins connecting the dural sinuses with the veins of the scalp skin.
38Diploic veins (frontal, anterior and posterior temporal, occipital): form a network between the external and internal compact bony layers of the skull and connect dural sinuses with the external veins.
39emissarydiploicEmissary veins (occipital, parietal, condylar, mastoid): pearce the skull directly and connect dural sinuses with external veins.
40Blood-brain barrier (BBB) The extracellular fluid of the CNS is separated from the blood by the BBB ensuring strictly controlled and mainly carrier protein assisted transport of macromolecules.Is formed by endothelial cells attached to one other by tight junctions, basement membrane, astrocytic endfeet.Protects the CNS from possibly toxic agents but makes development of medicines acting on the CNS difficult (e.g. antibiotics in infections).
41the circumventricular organs Life outside the BBB:the circumventricular organs„Circumventricular” = around the ventriclesIncomplet or missing BBBHighly capillarized structureSecretion of neurohormons or detection of hormons, glucose, ions, etc.
43Subfornical organsensoryfluid regulationOrganum vasculosumsensory, secretorydetects peptides, fluid regulationMedian eminencesecretoryregulates the anterior pituitary through the release of neurohormonesNeurohypophysisstore and secretes the hormones oxytocin and ADH into the blood, but does not synthesize either hormoneSubcommissural organsecretes certain proteins into the cerebrospinal fluid, its specific function is as yet unknown.Pineal glandstimulated by darkness to secrete melatonin and is associated with circadian rhythmsArea postremathe vomiting centre of the brain (can detect noxious substances in the blood and stimulate vomiting in order to rid the body of these toxic chemicals)
44The cerebrospinal fluid (CSF) Provides mechanical protection for the brain and the spinal cord.When floating in the CSF brain weights only 50g (!) according to the Archimedes’ principle.
45internal and external CSF spaces internal = ventricles external = subarachnoidal space