28 STROKE Flashcards
Main types of stroke
Ischemic- blockage of blood vessels
Haemorrhagic- rupture of blood vessel (burst aneurysm)
Describe the differences in focal and global strokes
Focal loss of blood to one area of brain (most common).
Global e.g. caused by cardiac arrest
Risk factors for stroke
Diabetes
Hypertension
Atherosclerosis
Genetic polymorphisms
Name the two forms of cells death and areas they occur in following focal stroke
Core or infarct zone- cells die by necrotic mechanism
Penumbra- area surrounding the central area, cells die by apoptosis mechanisms
Describe the excitotoxicity theory
Following stroke there is a massive release of Glutamate in the brain. Leads to pathological activation of glutamate receptors, causes increases in intracellular Ca2+, Na+, Cl and H2O. Ca2+ causes cell death through activation of Ca2+ sensitive enzymes that are apoptotic.
What are the three ionotropic glutamate receptors
NMDA- Ligand and voltage gated.
AMPA- Ligand gated
Kainate- Ligand gated
What channel allows the influx of Ca2+, describe how
With binding of glutamate AMPA channels allow depolarisation of post synaptic cells. Both binding of glutamate and the depolarisation allows the NMDA channels to open and Ca2+ influx occurs.
Describe Ca2+ influx through metabotropic channels
Binding of glutamate causes metabotropic channels to open and G-protein activation leading to cascades that allows for release of Ca2+ from intracellular stores.
Describe the causes of delayed cell death in the penumbra
Excessive glutamate causes increased Ca2+, apoptosis initiated.
Free radicals
Activation of brain macrophages, release of NO, superoxide, cytokines
Treatments of stroke
Tissue Plasminogen Activator (when ischaemic not hemorrhagic!)
Hypothermia
Free radical scavengers
Not really any treatment that works.
