The Aging Human Brain

The human brain weighs on average about three pounds, consists of 200 billion cells. Surprisingly, there are only two categories of brain cells, neurons and glia, but more than 50 different cellular subtypes. Nerve cells or neurons are specialized cells that are electrically
excitable,
and
processes
 and
 transmit
 information
 to
 other
 neurons
 and
 cells
 through
electrochemical
signaling
via
membrane‐to‐membrane
junctions.
Neurons
are
the
 basic
 structural
 and
 functional
 units
 of
 the
 human
 nervous
 system.
 There are about 100 billion neurons, and these make an additional 100 trillion connections to other cells at a velocity up to 250 miles per hour.