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Kurs: MCAT > Rozdział 2

Lekcja 1: Biological sciences practice passage questions

Effects of stroke on the brain


The disorder ischemic stroke involves focal dysfunction of tissue of the central nervous system caused by decreased blood flow to that area. Neurological functions of the affected area suddenly cease if the neurons are not continuously supplied by oxygen and glucose from the blood, due to their high metabolic demand and low intracellular energy stores. Energy failure kills many neurons, but many are also lost subsequently due to secondary cellular and molecular events that are harmful to tenuous neurons.
A researcher is studying the effects of ischemic stroke on the interstitial fluid composition of the brain in an animal model. The researcher is able to induce focal ischemia (tissue dysfunction from reduced blood flow) in the brain and sample the interstitial fluid at various time points after ischemia to analyze it for the concentrations of ions and other constituents. The researcher hypothesizes that the extracellular concentration of potassium ions will rise following ischemia, followed by an eventual return to normal. The researcher further hypothesizes that the concentration of the protein albumin, which is normally found in much lower concentration in the brain than in the blood, will follow a similar pattern as potassium ions. After this analysis, the researcher also plans to examine brain tissue sections to quantify the various cell types close to the area of tissue injury.
If the researcher in the passage is correct about increased albumin concentration in the interstitial fluid of the brain following focal ischemia, which of the following interactions would most likely be affected?
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