Nervous System
Chapter 14
Objectives:





Describe the nervous system
List the functions of the nervous system
Identify some clinical disorders
Review lab test and procedures
Identify some medical terms




Study of the Nervous System is:
Neurology
One who studies Neurology is a:
Neurologist
Nervous System:



Usually described as having two
interconnected divisions
The Central Nervous system (CNS)
The Peripheral nervous system (PNS)
Nervous system:



One of the most complex systems in the
human body
Sort of like your bodies built in computer
system but far more complex
There are over 10 billion nerve cells that
operate constantly all over the body
Contd:




Nerve cells are called neurons
Nerves are made of bunched together neurons
and their supporting tissue.
Collectively they are called neuroglia
Nerves either carry impulses to the brain and
spinal cord (sensory or afferent) or carry
messages from the brain and spinal cord (motor
or efferent).
Nervous system:


Control all involuntary (eyes dilating) and
voluntary movements (raising your
eyebrows)
Center for all mental activity such as
Thought process, learning and memory
Central Nervous system:



Includes the brain and spinal cord
Located in the skull and vertebral canal
It is the main control center of your body,
and the center of thought. Your Central
Nervous System controls most of the
actions within your body.
Contd:




2: Peripheral nervous system (PNS)
Which involve 12 pairs of cranial nerves
and 31 pairs of spinal nerves.
works in conjunction with the central
nervous system
Transmits sensory and motor information
between the CNS and rest of the body
PNS:

The peripheral nervous system (PNS) runs
from your spinal cord to your appendages
(arms, legs, hands and feet) and you DO
HAVE TO consciously and voluntarily make
this nervous system move or work.
Brain:






Weighs about 2.5 to 4 lbs
Consumes 25 % of its oxygen
Receives 15% of its cardiac output
Central control center for regulating and
controlling body functions
Lies in the cranial cavity
Size of skull does not dictate size of brain
Brain:




The brain and spinal cord are covered by 3
connective tissue layers
Dura mater, arachmoid and pia mater
collectively called the meninges
singular meninx
Contd:





The major structures of the brain are:
Cerebrum
Cerebellum
Diencephalon
brainstem
Brain contd: Cerebrum
Cerebrum is the main and largest portion
of the brain. Represents 7/8ths of total
weight
 It occupies the upper part of the cranial
cavity.
 It is the most superior portion of the brain's
anatomy.
 It is the part of the brain that controls
thought, memory and the senses.

Contd:


The cerebrum is divided into two parts - the right
hemisphere, which controls the left side of the
body; and the left hemisphere, which controls the
right side of the body.
The outer part of the cerebrum is called gray
matter and contains nerve cells. The inner part is
called white matter and contains connections of
nerves.
Contd:





Certain areas of the cerebrum perform
special activities:
Occipital Lobe
Interprets what you see
Frontal Lobe
The primary area for
thought, reason and speech
Temporal Lobe The hearing area
Parietal Lobe
The awareness of
sensation
Brain contd: Cerebellum:



Located behind the cerebrum at the back of
the head is the cerebellum.
contains more nerve cells than both
hemispheres combined.
When cut in half looks like a tree so
referred to as arbor vitae (tree of life)
Cerebellum contd:


The cerebellum is primarily a movement
control center, responsible for:
Voluntary muscle movements, Fine motor
skills, Maintaining balance, posture, and
equilibrium
Brain contd: Diencephalon


Means second portion of the brain
Thalamus and hypothalamus
Thalamus:



The largest of the two
The part of the brain that receives and
processes all sensory modalities, except
smell.
Sensations include vision, touch (including
pain, temperature, pressure), taste, and
hearing.
Hypothalamus:




Regulates body temperature, blood pressure,
heartbeat, metabolism of fats and carbohydrates,
and sugar levels in the blood.
It also plays a role in awareness of pleasure and
pain
It is involved in the expression of emotions, such
as fear and rage, and in sexual behaviors.
It is located below thalamus about the size of an
almond
Brain stem:


Is the lower part of the brain located in front
of the cerebellum and continuous with the
spinal cord
It is the main control panel for the body
that passes messages back and forth
between the brain and other parts of the
body
Brain stem contd:



The cerebrum, the cerebellum, and the spinal
cord are all connected to the brainstem.
It controls vital functions of the body:
Breathing ,Consciousness, Cardiac function,
Involuntary muscle movements, Swallowing,
Movement of the eyes and mouth, Relaying
sensory messages (pain, heat, noise, etc.) and
Hunger
Contd:



Brain stem contd: The brainstem has three main
parts:
The midbrain = joins the lower parts of the brain
stem and spinal cord with the higher parts of the
brain. (mesencephalon)
The pons= is a rounded bulge on the inferior side
of the brain stem where it separates the midbrain
from the medulla oblongata.
Brain stem contd:



medulla oblongata
is an enlarged continuation of the spinal
cord at its superior end.
It extends from the foramen magnum to
the pons.
Spinal Cord:
Encircled by white matter
that consists of
nerve tracts and fibers
 Adult spine is
about 44 cm long
 Extends down the
vertebral canal

Cerebrospinal Fluid:


The subarachnoid space, located between
the arachnoid membrane and the pia
mater, contains the cerebrospinal fluid
(CSF)
Normal adult has 120 – 150 mL in
circulation
Brain contd:



The CSF fluid cushions and supports the
brain
It acts as a shock absorber for the brain, to
prevent injury from the brain hitting against
the bony inside of the skull.
The fluid also carries nutrients and waste
products.
Peripheral nervous system (PNS)


is that portion of the nervous system that is
outside the brain and spinal cord.
It connects with the CNS, serving as a
conduit for neural signals to be transmitted
to and from the CNS to the body.
PNS:
Has 12 pairs of cranial
nerves
 Has 31 pairs of spinal
nerves

Cranial Nerves:



Provide :sensory input and motor control
12 pairs
Named for the function they serve
PNS contd:


the PNS is not protected by bone or the
blood-brain barrier, leaving it exposed to
toxins and mechanical injuries.
Without the peripheral nervous system, one
could not sense the external environment
(smell, sight, touch, taste, hear), and would
neither recognize threats or pleasurable
experiences.
Spinal Nerves:







31 pairs
Named for the region of the vertebral column
they exit
8 pairs of cervical spine nerves
12 pairs of thoracic spinal nerves
5 pairs of lumbar spinal nerves
5 pairs of sacral spinal nerves
1 pair of coccygeal spinal nerve
The PNS is divided into two
subsystems:


The somatic nervous system, or voluntary
nervous system, that regulates body movement
through control of skeletal (voluntary) muscles
also is the reception of external stimuli, such as
vision, hearing, taste, and smell.
It also controls such voluntary actions as walking
and smiling.
Contd:



autonomic nervous system (ANS)
acts involuntarily and consists of nerves in
cardiac muscle, smooth muscle, and
exocrine and endocrine glands.
responsible for metabolism, cardiovascular
activity, temperature regulation, digestion.
Root words:







Algesi/o
Cerebell/o
Cerebr/o
Dur/o
Ech/o
Encepha/o
Esthesi/o
excessive sensitivity to pain
Cerebellum
Brain, cerebrum
Dura mater
Sound
Brain
Feeling, nervous, sensation
Root words contd:






Kinesi/o
Mening/o
Ment/o
Myel/o
My/o
Neur/o
Movement
Membrane
Mind
Spinal cord
Muscle
Nerve
Root words contd:




Phas/o
Psych/o
Thalam/o
Ventricul/o
Speech
Mind
Thalamus
Ventricle
Prefixes:





HemiParaPolioQuadriSub-
Half
Beyond, around, beside
Gray
Four
Below, under
Suffixes:








-algia
-itis
-malacia
-paresis
-plegia
-schisis
-thenia
-us
pain
inflammation
softening
slight paralysis
paralysis
cleft or splitting
lack of strength
condition
Terms:




Affect: refers to an emotion or symptom.
Aggression: refers to behavior that is
intended to cause pain or harm
Amnesia: is a condition in which memory is
disturbed. In simple terms it is the loss of
memory.
Delusion: is a fixed belief that is either
false, fanciful, or derived from deception.
Contd:



Echolalia: The immediate and involuntary
repetition of words or phrases just spoken by
others.
Hallucinations: involve sensing things that aren't
there while a person is awake and conscious.
Megalomania: is a historical term for behavior
characterized by an obsession or preoccupation
with wealth, power, and genius,
Contd:


Phobia: is an irrational, intense, persistent
fear of certain situations, activities, things,
or people.
Comatose: is a profound state of
unconsciousness. A comatose person
cannot be awakened, fails to respond
normally to pain or light, does not have
sleep-wake cycles, and does not take
voluntary actions.