Block 1 Brain Metabolism Flashcards
How much of the body’s glucose does the brain use?
22%
Energy is coupled to blood flow
How much blood is in your brain at any point?
800ml
What tells a brain capillary to dilate?
Astrocytes
The do this by communicating with neuron synapses, when they see energy increase they increase blood flow
What is the energy used for in the brain?
44% is synaptic transmission
25% is housekeeping
15/16% for both resting potential and action potential
What are the four main pathways in the brain?
Glycolysis - hexokinase for phosphorylation, phosphofructokinase and pyruvate kinase are also important
Pentose phosphate pathway - transketolase and transaldolase for making NADPH
Gylcogen metabolism - important for memory
TCA and oxidative phosphorylation - isocitrate and alphaketogluterate dehydrogenase a
What does glycogen metabolism?
Astrocytes
What is wernicke-korsakoff syndrome?
Vitamin B1 def., thiamine. Because of transketolase
How do you measure arterial venous difference?
Cerebral Metabolic Rate
CMR = (a-v)(F/W)
A- arterial concentration
V- venous concentration
F- blood flow
W- weight
What is the CMR-02 and CMR-glucose ratio?
6/1
If it is not 6/1 then you are making lactate
How do you measure brain activity?
PET scan which uses 2-deoxyglucose
How is sight related to the occipital lobe?
Sight is coordinated in the occipital lobe and integrated throughout it. Both hemispheres control each eye
What is a PET scan normalized to?
The pons
Why, when you stimulate the visual cortex does oxygen consumption not increase?
Because the need for energy is so immediate the brain uses glycolysis rather than the TCA and oxidative phosphorylation.
How does the astorcyte coordinate vessel constriction and dilation?
glu released from the neuron is received by mGluR which breaks lipids (PLA2?) into AA.
Constriction: AA is converted into 20-HETE which signals constriction (adenosine prevents this)
Dilation: AA is converted into EETs and PGE2 which signal dilation, PGE2 is prevented form doing this by lactate because the presence of lactate means there is no need for more energy
What happens when there is too much pyruvate for oxidative phosphorylation?
Lactate is made. Aerobic glycolysis
