Glial cells are non-excitable cells in the nervous system. Their functions are supportive to the neurons. One type of glial cell is the astrocyte. One of its functions is to .

Explanation:

Glial cells are the cells present in both the type of nervous system in which they neither conduct electrical impulse nor generate them but they perform some other functions like support.

Astrocytes are one of the type of glial cells which are present in the central system of neurons that is in the spinal cord and the brain.

These astrocytes perform various other functions like  

1. Form the blood-brain barrier as they enclose the blood capillaries in the brain preventing leakage.

2. They regulate ionic concentration around the neurons.

3. They can store and produce glucose from the non-carbohydrate source.

4. They control the flow of the blood in the brain

5. They can also play a role in the formation of synapses in the neurons.

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.