1. This case study focuses on detecting differences in the relative concentrations of sodium (Na+) in the hippocampus (a region associated with memory) using magnetic resonance imaging (MRI); MRI usually is based on the magnetic behavior of hydrogen ions (H+) from water in the tissues. Because sodium also ionizes in the body fluids, it can be subjected to the magnetic fields that allow imaging in MRI.
The main theme is autopoiesis (application of energy to regulate life functions) as illustrated by the concentration gradients required for proper neuronal function.
(a) What role does the concentration of sodium ions ( Na+) play in neuronal action?
(b) Why is this approach relevant or useful to understanding the loss of function in neurons?
2. Describe the physiologic basis of the changes reported in the case.
(a) What is the normal concentration gradient of sodium in the nervous system (should the sodium concentration be higher or lower within the cell compared to the extracellular fluid)?
(b) How does the change in the sodium ion concentration detected from MRI of the hippocampus suggest that the neurons in the hippocampus became diseased and were not functioning properly?
(c) What sort of a change in the Na+ concentration gradient would you expect when neurons are damaged or malfunctioning?