The newest development of the brain is the
m.
7.
The autonomic nervous system (ANS) is that portion of the nervous system
concerned with commands for
th muscle tissue,
c muscle tissue, and
s.
For most of us, the control of the visceral organs is
c, that is, without
conscious control.
8.
The ANS is organized into two major subdivisions--the s
c and
p
c nervous systems. The first of these is also known as the
t
-l
outflow. The second is also known as the c
-s
outflow.
If one of these subdivisions stimulates an organ, the other will i
t it. The
interplay of the two subdivisions helps visceral organs to function within a stable
m. This tendency is called
s.
Under conditions of stress, the sympathetic nervous system mobilizes all of the
y-producing structures of the body. For example, it makes the heartbeat
(faster) (slower). Later, as equilibrium is restored, the parasympathetic nervous system
has the (same) (opposite) effect.
9.
The neurons are alined in sequences to form c
ts. The transmission of
information along a neuron is
cal in nature. Crossing the gap between
one neuron and the next is a chemical called a
r.
10.
Neurons are able to concentrate
tive ions inside and
tive ions
outside of the cell membrane. When the neuron is not actually transmitting, this
process produces the
g
l.
11.
When the polarity of ions is disrupted by a stimulus, that location on the cell
membrane is said to be
ized. The restoration of the original polarity is called
re
. At the same time, adjacent areas are depolarized. Thus, there is a
wave of d
/r
along the length of the neuron.
12.
The speed of an impulse is proportional to the
ness of the neuron process.
Transmission is fastest in the
est neurons.
MD0007
12-27
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