Which of the following has the slowest rate of movement across the blood-brain barrier? D-glucose ethanol glutamate carbon dioxide oxygen
Question
Which of the following has the slowest rate of movement across the blood-brain barrier? D-glucose ethanol glutamate carbon dioxide oxygen
Solution
The blood-brain barrier (BBB) is a highly selective semipermeable border of endothelial cells that prevents solutes in the circulating blood from non-selectively crossing into the extracellular fluid of the central nervous system where neurons reside.
The rate of movement across the blood-brain barrier depends on several factors, including the solubility of the substance in lipids (fat-soluble substances cross more easily), the size of the molecule, and whether or not there are specific transport mechanisms in place for that substance.
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D-glucose: Glucose is a primary source of energy for the brain. It crosses the BBB via facilitated diffusion through a specific glucose transporter.
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Ethanol: Ethanol is a small, lipid-soluble molecule, so it can easily cross the BBB.
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Glutamate: Glutamate is an amino acid neurotransmitter. It does not cross the BBB well because it is a large, charged molecule. However, there are specific transport systems in place for it.
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Carbon dioxide: Carbon dioxide is a small, lipid-soluble molecule, so it can easily cross the BBB.
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Oxygen: Oxygen is a small, lipid-soluble molecule, so it
Similar Questions
After a meal, when blood glucose spikes to over 10 mM, which glucose transporter is working furthest from its Vmax?Group of answer choicesGLUT3, because it has a very low Kt, which protects glucose supply to the brain.GLUT2, because it has a very high Kt, which helps regulate insulin production and removal of glucose from the blood.GLUT1, because it has a moderately low Kt, which provides a constant flow of glucose into most cells of the body to maintain their basal cellular functions.GLUT4, because its Kt is most similar to normal blood glucose levels.
After a carbohydrate-rich meal, when the blood glucose concentration more than doubles, which of the following glucose transporters would be operating closest to its Vmax? A. GLUT4, because its Kt is most similar to normal blood glucose levels. B. GLUT3, because it has a very low Kt, which protects the brain under starvation conditions. C. GLUT2, because it has a very high Kt, which helps regulate insulin production and removal of glucose from the blood. D. GLUT1, because it has a moderately low Kt, which provides a constant flow of glucose into most cells of the body to maintain their basal cellular functions.
From the list below, select three types of molecules that are permeable to the blood-brain barrier without requiring a transport protein.Check All That ApplyGlucoseGlucoseLarge proteinsLarge proteinsOxygenOxygenNicotineNicotineEthanolEthanolPolar moleculesPolar molecules
Which of the following is a factor in the velocity of nerve impulse conduction?
Which one of the following movements will be severely and immediately disrupted if the oxygen concentration in the blood becomes extremely low? A) Glucose from the lumen of the intestine into the villi B) Oxygen from the alveoli into the blood C) Urea from the blood plasma into the nephron D) Water from the blood plasma into muscle cells E) Water from the blood plasma into the nephron
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