BMB 1 - Strokes Flashcards
Under normal conditions, ______% of cardiac output is directed to the brain.
Under pathologic conditions such as generalized seizures, ______% of cardiac output is directed to the brain.
Under normal conditions, 15% of cardiac output is directed to the brain.
Under pathologic conditions such as generalized seizures, 50% of cardiac output is directed to the brain.
Hypoxia is when O2 saturation falls below _____%.
Hypoxia is when O2 saturation falls below 90%.
Ischemic thresholds for impaired function and injury are dependent on (1) the level of ____________ relative to metabolic demand and (2) on the _____ that cerebral blood flow is low.
Ischemic thresholds for impaired function and injury are dependent on (1) the level of cerebral blood flow relative to metabolic demand and (2) on the time that cerebral blood flow is low.
What types of factor can change the way an individual reacts to the length of time brain tissue is without oxygen under ischemic conditions?
Time scale will fluctuate with age, temperature, and other variables.
Remember, time is brain!
What cellular changes in [electrolyte] is seen within a few minutes of infarction of CNS tissue?
Efflux of intracellular K+
Influx of extracellular Na+ and Ca2+
True/False.
Upon thrombosis of CNS tissue, there is an immediate mass firing / increased activity of ischemic neurons and a subsequent mass hyperpolarization after a few minutes.
False.
Upon thrombosis of CNS tissue, there is a mass blockade / decreased activity of ischemic neurons and a subsequent mass depolarization after a few minutes.
True/False.
The most vulnerable regions of the brain can be irreversibly damaged if without perfusion for as little as one minute.
True.
Time is brain!
The spreading depression (seen in a focal stroke or other trauma) is a propagating wave of profound depolarization, characterized by __________ changes and __________ of the EEG.
The spreading depression (seen in a focal stroke or other trauma) is a propagating wave of profound depolarization, characterized by vascular changes and flattening of the EEG.
True/False.
The profound depolarization seen in ischemic CNS tissue sends the patient’s cells into an absolute refractory state.
True.
What are some of the mechanisms common to all schemes of neuronal death?
Energy failure, depolarization, swelling, and influx of calcium ions
What term refers to the fact that neurons in different brain regions are more or less susceptible to ischemia?
Selective vulnerability
What term refers to the fact that the major consequences of hypoxic/ischemic CNS injury (loss of neurons) are delayed for a minimum of one to several days following an insult?
Delayed neuronal death
The _____________ is the area of cerebral infarction, while the _____________ is the surrounding region in which blood flow is below normal but is sufficient to meet the metabolic demands of normal neuronal activity.
The ischemic core is the area of cerebral infarction, while the penumbra is the surrounding region in which blood flow is below normal but is sufficient to meet the metabolic demands of normal neuronal activity.
Under what condition is the penumbra of a stroke an area that is also irreversibly damaged (usually, only the ischemic core is irreversibly damaged.)?
If suffering repeated episodes of spreading depression
(i.e. peri-infarct depolarizations)
What is significant about peri-infarct depolarizations (spreading depolarizations surrounding the ischemic core)?
The peri-infarct depolarizations have a much higher metabolic demand than normal neuronal activity.
As a result, there are repeated episodes during which metabolic demand exceeds supply of oxygen and glucose from the circulation.
This constitutes a relative ischemia, which leads to gradual recruitment of the penumbra into a progressively enlarging ischemic core.
