Case 5 - Extra Flashcards
what does the anterior cerebral artery supply
medial portions of the frontal lobes
superior medial parietal lobes
anterior four fifths of the corpus callosum
anterior portions of the basal ganglia an internal capsule
olfactory bulb and tract
where does the anterior cerebral artery pass
passes forward to travel in the inter hemispheric tissue as it sweeps back and over the Corpus callosum
what are the two main branches of the ACA
pericallosal artery - this forms an anastomosis with the PCA
callosmomarginal artery
where does the middle cerebral artery travel
turns laterally to enter the depths of the Sylvian tissue. within the Sylvia tissue, it usually bifurcates into the superior and inferior divisions
the branches of the MCA form loops as they pass over the insula and then around and over the operculum to exit the Sylvia fissue onto the lateral convexity
what does the superior division supply
the cortex above the Sylvian fissure, including the lateral frontal lobe and usually the peri-rolandic cortex
what does the inferior division supply
the cortex below the Sylvian fissue, including the lateral temporal lobe and a variable portion of the parietal lobe
where does the posterior cerebral artery travel
curves back after arising from the top of the basilar and sends branches over the inferior and medial temporal lobes and over the medial occipital cortex
what does the PCA territory therefore include
the inferior and medial temporal and occipital cortex
what are the three things that cause ischaemic damage:
neurotransmitters - glutamate
ions - sodium and calcium
free radicals - abnormal oxygen molecules egg superoxide
excitotoxicity explanation
- hypoxia leads to inadequate supply of ATP which in turn leads to failure of membrane pumps
- this causes an increased release of the excitatory neurotransmitter glutamate into the extracellular fluid
- this causes a rapid influx of calcium and sodium ions into the cells in the immediate area
- the calcium overload in the cells triggers a wide range of processes including, eventually leading leading to the formation of free radicals.
- the processes that occur inside the cell, leading to free radical formation ate:
mitochondrial injury
increased production of nitric oxide
protease activation
phospholipase activation
what is free radical formation
this is induced in the brain
there is formation of superoxide and nitric oxide, which combine together to form superoxynitrate
what does the formation of these radicals result in
lipid periodisation
protein oxidation
DNA damage
what is apoptosis
excitotoxicity results in necrosis at the onset of injury
apoptosis is programmed cell death that occurs much later than the onset of the injury
how does apoptosis occur
oxidative stress causes mitochondria injury
this causes release of cytochrome C from the mitochondria
cytochrome C activates the paracaspases into caspases
this leads to DNA damafe and cell death
what is central inflammation
occurs in the brain and involves the microglia
what does central inflammation cause
the degradation of the extracellular matrix in the brain, leakage of the BBB and the activation of the endothelial cells in the brain
what is peri inflammation
the liver becomes activated due to the release of chemokine from the brain
it causes the liver to expresses acute phase proteins and other chemokine and cytokines
these cause an increased production of neutrophils which contain IL-1
due to the leakage of the BBB the neutrophils infiltrate the brain
when is the outcome of a stroke pore
if you already have an inflammatory condition like obesity and arthritis
what are watershed infarcts
the term watershed refers to those areas of the brain that receive dual blood supply from the branching ends of two very large arteries
the. the blood supply to two adjacent cerebral arteries is compromised, the regions between the two vessels are the most susceptible to ischaemia and infarction
where are the bilateral watershed infarcts usually
in both the ACA-MCA and MCA-PCA watershed zones and can occur with severe drops in systemic BP
what can watershed infarcts cause
in the dominant hemisphere, they can cause transcortical aphasia syndromes
MCA-PCA watershed infarcts can cause dsturbances of higher order visual processing
what is transient global amnesia sully due to
posterior circulation ishcameia
what is memory
the mental capacity to store and later recall or recognise events that were previously experienced
what does learning emphasise
what is retained
what does memory emphasise
what is forgotten
what are the three stages of memory
perception
storage
retrieval
facts about the short term memory
lasts seconds to minutes
capacity is limited to 7+/- 2 pieces of information: rule of 7
which part of the brain is essential for consolidation learning
the hippocampus
what is the mutlistore model of memory
information is detected by the sense organs and enters the sensory memory
this information is attended to, enters the short term memory, around 20 seconds
information from the STM is transferred to the long term only if that information is rehearsed
if rehearsal does not occur, then information is forgotten, lost form STM through the processes of displacement or decay
where does conscious processing take place
the STM
what is the model of working memory
in this model instead of all the information going into one single store, there are different systems for different types of information
what does the working memory consist of
a central executive which controls and co ordinates the operation of two subsystems; the phonological loop and the visuospatial sketchpad
what is the central executive
drives the whole system and allocates data to the sub systems
it also deals with cognitive tasks such as mental arithmetic and problem solving
what is the visuo-spatial sketchpad
stores and processes information in a visual or spatial form
the VSS is used for navigation
what is the phonological lop
it deals with spoken and written material.
what are the two parts the phonological loop consists of
phonological store - linked to speech perception. hold information or speech based form for 1-2 seconds
articulatory control process - linked to speech production. used to rehearse and store verbal information from the phonological store
what is the phonological loop responsible for
the manipulation of speech based information whereas the visuospatial sketchpad is assumed to be responsible for manipulating visual images
what does this model propose
that every component of working memory has a limited capacity and also that the components are relatively independent of each other
what is the episodic buffer
this is dedicated to linking information across domains to form integrated units of visual , special and verbal information and chronological ordering
what is the difference between stroke and bells palsy
you get forehand spearing in a stroke unlike bells as It is a low motor neurone lesion
