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32 Cards in this Set
- Front
- Back
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Brain metabolism is based almost entirely on the oxidation of
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glucose
(^primary substance for energy metabolism in brain under normal circumstances) |
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The Major (50%) use of glucose metabolism is expended in?
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maintenance of membrane potentials
(primarily via the Na-K ATPase pump) |
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Minor use of glucose metabolism is for?
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Neurotransmitter synthesis (gluamate, GABA, Acetylcholine)
glycoprotein and glycolipid synthesis |
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Na+/K+ ATPase is particularly active in
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Astrocytes
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Na+/K+ ATPase is particularly active in Astrocytes and stimulated by
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glutamate
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Anoxia or metabolic poisons can result in?
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membrane depolarization
(often resulting in seizure activity) |
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The major interface for the transport of glucose from blood to neurons?
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Astrocytes
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Can act as a reservoir for glycogen
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Astrocytes
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Can also act as a carbohydrate source for brain metabolism but is not commonly available and is absorbed slower?
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Mannose
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_____can become an energy source for the brain under conditions of neonatal sucking, diabetes, starvation and low carb intake
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Ketone Bodies
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_____ appears to be an energy source released by Astrocytes at the synaptic level.
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Lactate
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Lactate is stimulated to be released by astrocytes via the release of?
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Glutamate
(synaptic activity) |
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2/3 of the vascular resistance is attributed to the ________ and the remaining 3rd controlled within the __________
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1. pial vessels
2. vascular tissue beds |
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under normal circumstances cerebral blood flow is TIGHTLY coupled to
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metabolism
*fxn for magnetic imaging |
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Increase in neuronal activity are rapidly accompanied by:
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vasodilation and increase blood flow
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The end regulators in metabolism being tightly coupled to cerebral blood flow are?
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1. Nitrous Oxide
2. Adenosine |
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Adenosine can be produced in association with ATP utilization and causes
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vasodilation
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What is the most potent regulator of the resistance of cerebral capillary beds?
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Carbon Dioxide
(vasodilator) |
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Carbon Dioxide produces changes in hydrogen ion concentration in perivascular fluid which in turn activates
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Mediators (NO and Adenosine)
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Hypercapnia
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increase in CO2 --> vessel dilate
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Hypocapnia
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decreased CO2 --> Vessel Constrict
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Cellular level:
Astrocytes play a role in the regulation of cerebral blood flow through mechanisms related to |
Calcium regulation and arachidonic acid metabolites
*Calcium is an important intermediate in cerebral blood flow regulation |
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Mechanical (myogenic) autoregulation of blood flow is related to
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Level of larger arteries:
intraluminal pressure (arterial blood pressure) *fast & slow mechanisms of regulation |
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_________ is the most abundant perivascular neurotransmiteer
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Acetylcholine
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The Primary anatomical substrates for the blood brain barrier include:
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1. Tight Junction **** (anatomical basis for BBB)
2. Perivascular cells 3. Basement membrane 4. Astrocytic endfeet that surround cerebral capillaries |
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Permeability of the blood-brain barrier is inversely proportional to
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molecular size
(large molecules cannot diffuse, no fenestrations) |
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permeability of the blood-brain barrier is directly proportional to
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lipid solubility
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the blood brain barrier generally does not allow the passage of
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plasma proteins or drugs that are bound to them
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3 major mechanisms regulate cerebral blood flow
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1. metabolic- metabolism & blood flow are directly related (linear relationship)
2. myogenic- control tone of arteries, etc 3. neurogenic- neural innervation of vessels |
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Under pathological conditions, cerebral perfusion (is/is not) regulated
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is not regulated
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Severe hypertension may lead to _____________
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edema
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Decreased perfusion may lead to _________
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ischemia & infart
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