Which of the following is not a function of astrocytes?
a) support and brace neurons
b) anchor neurons to blood vessels
c) guide the migration of young neurons, synapse formation, and to determine capillary permeability
d) control the chemical environment around neurons
e) provide the defense for the cns

The correct answer is: E) provide the defense for the CNS

Astrocytes are star-shaped cells found in central nervous system (brain and spinal cord) .Some of their functions include:

•Support of neurons by supporting endothelilal cell of blood–brain barrier,

•Provide nutrients to neurons

•Maintain ion balance and thus controlchemical environment around neurons

•Repair of injuries in the brain

•the secretion or absorption of neural transmitters…

The cells that provide the defense for the CNS are called microglia. Those cells are also glial cells, derived from macrophages and thus, part of active immune defense.

a fossil fuel is a fuel formed by natural processes, such as anaerobic decomposition of buried dead organisms, containing energy originating in ancient photosynthesis.[1] the age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years.[2] fossil fuels contain high percentages of carbon and include petroleum, coal, and natural gas.[3] other commonly used derivatives include kerosene and propane. fossil fuels range from volatile materials with low carbon to hydrogen ratios like methane, to liquids like petroleum, to nonvolatile materials composed of almost pure carbon, like anthracite coal. methane can be found in hydrocarbon fields either alone, associated with oil, or in the form of methane clathrates.

the theory that fossil fuels formed from the fossilized remains of dead plants by exposure to heat and pressure in the earth's crust over millions of years was first introduced by andreas libavius "in his 1597 alchemia [alchymia]" and later by mikhail lomonosov "as early as 1757 and certainly by 1763".[4] the first use of the term "fossil fuel" was by the german chemist caspar neumann, in english translation in 1759.[5]

in 2017 the world's primary energy sources consisted of petroleum (34%), coal (28%), natural gas (23%), amounting to an 85% share for fossil fuels in primary energy consumption in the world.[6] non-fossil sources in 2006 included nuclear (8.5%), hydroelectric (6.3%), and others (geothermal, solar, tidal, wind, wood, waste) amounting to 0.9%.[7] world energy consumption was growing at about 2.3% per year. in 2015 about 18% of worldwide consumption was from renewable sources.[8]