Neurology lecture 5 – Flashcards
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Describe the Blood-CSF barrier (1) and the Blood Brain Barrier (3)
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*movement from Ventricle to brain NOT tightly controlled --ependymal lining of ventricles is leaky, whenever brain enters ventricles, whatever is in ventricles enters brain *but movement of fluid from Ventricles to blood controlled by BBB --prevents exposure of neruons in brain to Drugs, waste products, and variations in levels of normal substances --strictly regulates what substances can enter ISF (see plasma proteins, important for avoiding osmotic edema)
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Describe the components of the BBB Endothelial cells and Astrocytes
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*endothelial cells - form tight junctions that prevent materials from diffusing across capillary wall *astrocytes: "gatekeepers" that permit materials to pass to neurons after leaving capillaries --interposed between neurons and capillaries
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Where is BBB markedly reduced? Why?
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*choroid plexus, hypothalamus, and pineal gland *circumventricular organs have no BBB --capillaries in CVO are permeable to circ. macromolecules --sense danger and send signals to monitor and reg.
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What happens in the even of a tumor in Pineal Gland Pituitary gland
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*Pituitary - visual disturbance / hormonal changes *pineal - hydrocephalus
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Describe the blood supply to the brain (in general)
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*17% of total CO and 20% of total oxygen *dependent on continuous supply of oxygenated blood
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Describe the 2 branches of the internal carotid artery
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*Note, common carotid receives 80% of BF to brain *Anterior choroidal --optic tact --posterior limb of internal capsule --branches of midbrain --lateral geniculate nucleus *opthalmic artery --eyeball and ocular muscles *major sources of blood to brain --after joinign CoW becomes anterior and middle cerebral arteries
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Describe the supply from the two main systems of brain arterial blood Carotid (4) Vertebral (3) Common (1)
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*carotid --middle --anterior --cerebral arteries --opthalmic artery *verterbral basillar system (via numerous vessels) --brainstem --spinal cord --cerebellum *both supply hemispheres)
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What does the internal carotid supply? What are its 4 branches?
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*supply each hemisphere *branches --ACA --MCA --Anterior choroidal artery (prone to thrombosis) --Opthalmic (rise to central artery of retina)
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Describe the branches of the basillar artery (4)
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*Anterior inferior cerebellar (AICA) --anterior surface and underlying white matter of cerebellum --upper medulla --lower pontine areas *Pontine arteries -pons --middle cerebellar peduncle --floor of 4V *Superior cerebellar arteries --close toPons-midbrain junction --runs along dorsal surface of cerebellum *Posterior cerebral arteries (PCA) --term. branches of Bas. Art. --Curves around midbrain and reaches out to post. cerebral hemispheres
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What are the branches of the vertebral artries? where do they join?
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*branches --anterior spinal arties (ASA) --Posterior inferior cerebellar arteries (PICA) *join at junction of Pons and medullar = basillar artery
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Describe the branches of the PCA in more detail
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*Surface branches --cortex and white matter of occipital lobes --inf temporal lobes --post. corpus callosum *penetrating --parts of thalamus --parts of midbrain
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What supplies blood to the brain stem?
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Vertebrobasilar system
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Describe blood flow the the medulla and pons
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*medulla --mainly through Post. Inf. cerebelar art. thorugh vertebral arteries --also through Anterior spinal artery *Pons --mainly through SCA via BA
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Note the locations of the following, what doe they supply? superior cerebellar Pontine labyrinthine anterior inf. cerebellar post. inf. cerebellar
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Supply cerebellum
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Describe the branches from the circle of willis
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*ant. communicating *ant. cerebral *post. communicating *post. cerebral *all referred to as cerebral arterial circle
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Describe the central penetrating arteries and what they supply (5)
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*arise from CoW *penetrate inf. surfaceof brain *form channels to facilitate blood supply *Supply --thalamus --hypothalamus --Basal ganglia --internal capsule --choroid plexus
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Contrast cortical and central arteries
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*cortical (circumferential) --supply external brain structures *central --small --penetrate surface to supply internal brain structures
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What do the surface and penetrating branches of the MCA supply?
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*surface --cortex / white matter of hemispheric convexity --all 4 lobes and inusla *penetrating --deep white matter --some diencephalic structurs --lateral straite branches (Basal ganglia, internal capsule)
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Explain the significance of collateral circulation
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*redundant arteries provide alternative supply when primary supply lost *small, normally closed arteries open up after occlusion *connect two larger arteries or different parts of same artery
