Which of the following statements regarding neurons is true?

How many electrons need to be held in the valence shell for an atom to achieve chemical stability (with the exception of helium and hydrogen)?

The central nervous system is composed of primarily which category of neurons?

Which of the following belongs to the cellular level of organization?

Which of the following substances is vital to the stability of the plasma membrane and regulates its fluidity?

Which of the following topics would be of interest to a physiologist, but not to an anatomist?

John is drifting off to sleep in a quiet room. He is unaware of the repetitive hum of his air conditioner. A sudden flash of lighting and peal of thunder suddenly occurs. John is now wide awake, and has trouble getting back to sleep. Which region of his brain is responsible for these behaviors? 

When a cell becomes more negative than at rest, either due to the loss of cations or entry of anions, this is known as a [answer1]. When a cell becomes less negative than at rest, through the entry of cations or loss of anions, this is known as a [answer2].

All of the following are functions of astrocytes except:

Which of the following is not one of the functions of the nervous system?