Practice Passage Test - 1 | Practice Passages for MCAT PDF Download

Culturing neurons in vitro involves cultivating immature neural cells from rodent fetal brains in a controlled laboratory environment. By providing appropriate nutrients and periodically altering the culture medium, these cells develop into fully functional neurons with similar characteristics to neurons in living organisms. This allows researchers to investigate various aspects of neuronal behavior and function under controlled conditions.

In a particular study, a scientist is examining cultured neurons to explore the behavior of a recently discovered ion channel. By manipulating the opening and closing of these channels, the scientist can observe changes in the neurons' membrane potential. The initial membrane potential is -60 mV, but when a large number of the ion channels are opened, the potential shifts to -50 mV. Additionally, the scientist investigates the effects of altering the extracellular concentrations of different ions on the membrane potential. Decreasing the extracellular concentration of sodium ions does not significantly affect the membrane potential, which remains at -60 mV. However, reducing the extracellular concentration of chloride ions or calcium ions leads to a membrane potential of -50 mV. These findings provide insights into the behavior of neurons and the role of ion channels in regulating their electrical activity.