There are approximately ten times as many glial cells in the nervous system as there are neurons. Collectively, the different types of glial cells perform very important functions in the nervous system. Test your basic knowledge of glial cells by taking this simple quiz.
(1) These glial cells play a critical role in the formation of the blood-brain barrier.
(2) During high-frequency neuronal activity, increases in the extracellular potassium (K+) concentration may be observed around axons. The excess extracellular K+ is generally removed by glial cells via a process called K+ buffering. Which of the following processes may play a role in K+ buffering?
(3) In general, astrocytes have very negative resting membrane potentials of approximately −90 mV.
(4) These glial cells are responsible for the secretion of the cerebrospinal fluid (CSF).
(5) These glial cells are thought to be derived from bone marrow, enter the central nervous system early in development, and reside within the central nervous system throughout the lifespan.