Biochem- Metabolic profile of the Brain Flashcards
What are the two major cell types of the CNS?
Neurons and Glia
What are the two major kinds of Glial cells?
Oligodendrocytes
Astrocytes
What is the fucntion of the oligodendrocyte?
Produce the myelin sheath in the CNS
What is the major function of the Astrocyte?
-provide metabolic support and protection for the neurons
What is the function of the microglia?
resemble macrophages, and appear to protect against infection and clear cellular debris
The function of the _______ cell is to line the venticles and profuce, circulate and monitor the CSF.
Epindymal cell
Tight junction between the BBB endothilial cells provide protection from most molecules, but what are some notable exceptions?
Caffeine
Nicotine
Alcohol
Cocaine
How does the BBB transport molecules of which it needs large amounts?
-Facilitated diffusion (glucose) and active transport (ion concentraion)
What are the two chief glucose transporters found in the brain?
GLUT1 and GLUT3
What is special about the kinetics of the GLUT1 and GLUT3 transporters that make them well adapted for the BBB?
Low Km which permits constant and efficient glucose uptake.
What is the main purpose of amino acid transporters?
-Promote the efflux of potentially harmful NT (gltamate) and the influx of essential amino acids (tyr and try)
What is the theory behind sports drinks that contain branched chain amino acids?
-the BCAA compete with trytophan fo transport into the brain which reduces the trytophan uptake. Tryptophan is a precursor of 5-HT and melatonin which are involved in tiredness, relaxation and sleep.
What enzyme is defficient in phenylketonuria?
-phenylalanine hydroxylase
What is the action of phenylalanine hydroxylase?
-converts Phenylalanine to tyrosine
What is the result of high levels of phenylalanine in PKU?
-mental retardation in infants and reduced uptake of tyrosine–> less melanin and therfore less pigementation
How long does the BBB remain defective, even after a reversible inury?
2-3 weeks
How high is the rate of blood supply to the brain?
Very high: 10x that of resting muscle or adipose tissue
What is the brain’s main supply of energy? Can it absorb fatty acids?
- Glucose
- No it can not absorb fatty acids
What does the brain use for energy during periods of starvation?
-Ketone bodies
What are the principle uses of the energy that is required by the brain?
- Transport processes (ion gradients)
- Synthesis of NT and neuromodulators (peptide synthesis)
How is NADPH provided through glucose metabolism?
-through the pentose phosphate pathway
What are the main requirements of NADPH by cells in the CNS?
- Fatty acid synthesis (myelogenesis)
- Glutathione reductase (antioxidant)
