1: Mind Body Connection
3: The Brain and Nervous System
The Brain and Nervous System
The nervous system is broken down into two
major systems: Central Nervous System and Peripheral Nervous System. Well
discuss the Central Nervous System first.
Nervous System consists
of the brain and the spinal cord. The Cerebral
Cortex, which is involved in a variety of higher cognitive,
emotional, sensory, and motor functions is more developed in humans than any
other animal. It is what we see when we picture a human brain, the gray
matter with a multitude of folds covering the cerebrum.
The brain is divided into two symmetrical hemispheres: left
(language, the rational half of the brain, associated with
analytical thinking and logical abilities) and right
(more involved with musical and artistic abilities). The brain is also divided into four lobes:
Frontal (motor cortex) motor behavior,
expressive language, higher level cognitive processes, and orientation to
person, place, time, and situation
Parietal (somatosensory Cortex) involved in
the processing of touch, pressure, temperature, and pain
Occipital (visual cortex) interpretation of
Temporal (auditory cortex) receptive language
(understanding language), as well as memory and emotion
Typically the brain and spinal cord act
together, but there are some actions, such as those associated with pain,
where the spinal cord acts even before the information enters the brain for
processing. The spinal cord consists of the Brainstem which is involved in life sustaining functions. Damage to the
brainstem is very often fatal. Other parts of the brainstem include the
controls heartbeat, breathing, blood pressure, digestion; Reticular
System (Reticular Formation), involved in arousal and attention, sleep and wakefulness, and control
regulates states of arousal, including sleep and dreaming.
balance, smooth movement, and posture
"central switching station"
relays incoming sensory information (except olfactory) to the brain
controls the autonomic nervous
system, and therefore maintains the bodys homeostasis, which we will
discuss later (controls body temperature, metabolism, and appetite.
Translates extreme emotions into physical responses.
emotional expression, particularly the emotional component of behavior,
memory, and motivation
attaches emotional significance to
information and mediates both defensive and aggressive behavior
involved more in memory, and the
transfer of information from short-term to long-term memory
Nervous System is
divided into two sub-systems. The Somatic
Nervous System primary
function is to regulate the actions of the skeletal
muscles. Often thought of as mediating voluntary activity.
The other sub-system, called the Autonomic
Nervous System, regulates
primarily involuntary activity such as heart rate,
breathing, blood pressure, and digestion. Although
these activities are considered involuntary, they
can be altered either through specific events or through
changing our perceptions about a specific experience.
This system is further broken down into two complimentary
systems: Sympathetic and Parasympathetic Nervous
Nervous System controls
what has been called the "Fight or Flight" phenomenon because of
its control over the necessary bodily changes needed when we are faced with
a situation where we may need to defend ourselves or escape. Imagine
walking down a dark street at night by yourself. Suddenly you hear
what you suspect are footsteps approaching you rapidly. What happens?
Your Sympathetic Nervous System kicks in to
prepare your body: your heart rate quickens to get more blood to the
muscles, your breathing becomes faster and deeper to increase your oxygen,
blood flow is diverted from the organs so digestion is reduced and the skin
gets cold and clammy and rerouted so to speak to the muscles, and your
pupils dilate for better vision. In an instant, your body is prepared
to either defend or escape.
Now imagine that the footsteps belong to a
good friend who catches up to you and offers to walk you home. You
feel relief instantly, but your body takes longer to adjust. In order
to return everything to normal, the Parasympathetic
Nervous System kicks
in. This system is slow acting, unlike its counterpart, and may take
several minutes or even longer to get your body back to where it was before
These two subsystems are at work constantly
shifting your body to more prepared states and more relaxed states.
Every time a potentially threatening experience occurs (e.g., someone slams
on their breaks in front of you, you hear a noise in your house at night,
you hear a loud bang, a stranger taps you on the shoulder unexpectedly),
your body reacts. The constant shifting of control between these two
systems keeps your body ready for your current situation.
Here to Take the Chapter Quiz