Notes Chapter 7 Nervous System
Purpose of the system
1. Monitor changes in the environment (Sensory)
2. Process and interpret information (central nervous system)
3. Effect a response by activating muscles or glands (Motor)
Overview of Nervous system
http://www.youtube.com/watch?v=xx--f9Y8wjg&feature=related
Two Primary Subdivisions of the Nervous system are:
 Central Nervous system---includes Brain and Spinal Cord
 Peripheral Nervous system--- Sensory and Motor nerves
Nerve Cells and Tissues- the primary cell of the nervous system is called a NEURONNeurons conduct information in electrical waves called Impulses. In addition to Neurons,
other cells that support neurons are called neuroglia (Nerve Glue). They include




Astrocytes- Star shaped cells that connect nerves to blood vessels
Microglia- Small cells that dispose of cellular waste
Ependymal- Lining cells of the brain and spinal cord that are ciliated and circulate
spinal fluids
Oligodendrocytes- cells that cover nerve fibers and provide insulation
Structure of a Typical Neuron
Anatomy and Physiology of a Neuron
DendriteAxonCell BodySchwann CellMyelin SheathNodes of RanvierAxon Terminal-
Receives information from a sense organ or other nerve
Sends information from the nerve to another nerve or muscle
Primary part of the nerve cell that contains the nucleus
support cell that surround the axon
series of schwann cells that surround the axon
spaces between the Schwann Cells
multiple endings of the axon
Nerve Impulse- A nerve impulse is the movement of an electrical wave the length of the
neuron from its dendrites towards its axon terminal. The change in cell membrane
polarity occurs when sodium and potassium ions move into and out of the cell. The
impulse travels quickly along the cell. Animation follows:
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter14/animation__the_nerve_impulse.html
Synapses and Neurotransmitters- The Axon terminals carry nerve impulses to one of
three locations…..another neuron, a muscle cell or a gland. The gaps between these cells
are celled Synapses.
Neurotransmitters are chemicals that continue impulses across the synapse to the next
cell. Key Neurotransmitters include Acetylcholine, Norepinephrine, Serotonin and
Dopamine.
Animation: http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter14/animation__transmission_across_a_synapse.html
Classification of Neurons
1. Function- Neurons are either Sensory, Motor or Interneuron’s
2. Structure-Neurons have differing numbers of Dendrites or Axons
3. Physiology- Impulse- conscious or Reflex- unconscious action
Central Nervous System- (Brain and Spinal Cord)
In the early stages of embryonic development, the brain and spinal cord form on the
outside of the body and within the first month becomes part of the neural tube. The brain
enlarges and forms four lobes while the spinal cord is covered. Spina Bifida can occur if
the spinal cord is left exposed.
The Human Brain has four distinct parts
Cerebrum
Diencephalon
Brain Stem
Cerebellum
1. Cerebrum (aka cerebral cortex or cerebral hemispheres)
a. The largest region of the brain, it covers the diencephalon and brain stem
b. Is divided into hemispheres by a deep fissure
c. Is grey in color
d. Has a wrinkled appearance that increases surface area
e. Lobes of the brain are named for the bones above them and they are
specialized
-Frontal Lobe- Motor and behavior area
-Occipital Lobe- Visual area
-Temporal Lobe-Auditory and olfactory area
-Parietal Lobe- Primary sensory area
The outer area of the brain is referred to as “Grey Matter”. This is the area where most
conscious thought processes originate.
Deeper in the brain the color is white as many nerves fibers run through the region. The
largest tract of these fibers is called the corpus callosum.
2. Diencephalon- (Interbrain) Sits atop the brain stem and is enclosed by the
cerebrum. An area of nerve and hormone activity. Its parts are:
a. Thalamus- sensory relay center
b. Hypothalamus- Controls the Autonomic nervous system and Pituitary
gland. Area of hormonal control
c. Epithalamus-the top of this region, it contains the pineal gland and the
choroid plexus (Brain capillaries) and Corpus Callosum.
3. Brain stem- the top 3 inches of the spinal cord found within the cerebrum. It
consists of the
a. Midbrain-the top of the stem
b. Pons- a primary bridge of fibers
c. Medulla Oblongata-a merged area of the spinal cord that controls heartrate, blood pressure, swallowing and vomiting
http://www.youtube.com/watch?v=UfC4u5GCy3I (medulla oblongata)
4. Cerebellum- A Large Cauliflower shaped structure below the occipital lobe.
It coordinates motor activity, balance and equilibrium. Injury to this area
produces uncoordinated and clumsy movement.
Brain Diagram:
Spinal Cord- The extension of the brain stem







Runs from the magnum foramen to the L2 vertebrae
Is approximately 17 inches in length
Is about 1 cm in diameter
Is protected by 3 layers of meninges
Has 31 pair of spinal nerves that branch away from it
Below the L2 vertebrae, a bundle of nerves called the cauda equina (horses tail)
branch to the lower extremities.
Responsible for reflex arc which does not involve the brain
Four Protections of the Brain and Spinal Cord
1. Skull and Vertebrae.-bone protection from physical injury
2. Meninges- Three layers of Connective tissue that protects the brain from viral and
bacterial infection
 Dura Mater- tough membrane on the outside
 Arachnoid mater- web-like network of blood vessels
 Pia mater- delicate membrane that clings to the brain.
3. Cerebrospinal Fluid (C.S.F.) produced from blood plasma, it circulates around
and within the brain. Supplies the region with immune system cells
4. Blood Brain Barrier- (B.B.B.) a fine network of blood vessels that protect the
brain from virus and bacteria infection. Supplies oxygen to the cerebral cortex
Peripheral Nervous System (PNS) consists of all nerves and ganglia outside of
the Central Nervous system.
Nerve- a bundle of neurons fibers that may either be sensory or motor in function.
Each nerve contains neurons bound together in specific groups. Nerves also have
individual blood vessels within them to supply the neurons with oxygen and
nutrition. Since nerves contain both sensory and motor neurons, a nerve can
supply each area of the body with the Reflex Arc
Types of Peripheral Nerves
 Cranial Nerves- There are 12 pair of nerves that leave the brain other than
by way of the spinal cord. Most control some aspect of the head and neck.
Six examples of Cranial nerves
1. Optic- sensory- for vision
2. Occulomotor- motor- controls movement of the eyes
3. Olfactory- sensory- sense of smell
4. Facial- sensory and motor- affects neck and face
5. Vestibulocochlear- sensory- for hearing and balance
6. Vagus- motor- affects heart rate respiration, digestion and reproduction

Spinal Nerves- There are 31 pairs of spinal nerves that branch laterally
from each vertebrae and within the sacrum. Important ones like Brachial
and Femoral control arms and legs. The Sciatic nerve (largest nerve)
emerges from the sacrum. The Ulnar nerve controls wrist and hand
movements.
o Somatic Nervous System- All motor nerves that directly affect the actions
of muscles. This system is under complete voluntary control.
o Autonomic Nervous System- Division of the motor nerves that affect the
body without conscious thought. Included are nerves that control the heart,
smooth muscles, pupil movement and endocrine glands.
Common Diseases and Disorders of the Nervous System
Huntington’s Diseasehttp://video.search.yahoo.com/video/play;_ylt=A2KLqIAAT4VQyzUAd4j7w8QF;_ylu=X3oDMTBrc3VyamVwBHNlYwNzcgRzbGsDdmlkBHZ0aWQD?p=huntington+s+disease&vid=F215BC575CA0892AFB17F215BC575CA0892AFB17&l=4%3A30&turl=http%3A%2F%2Fts1.mm.bing.net%2Fth%3Fid%3DV.4897255619166212%26pid%3D15.1&r
b
url=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DMRZoM5L5dak&tit=Huntington%26%2339%3Bs+disease&c=3&sigr=11abbq10i&fr=yfp-t-521&tt=
Parkinson’s Diseasehttp://video.search.yahoo.com/video/play;_ylt=A2KLqIVUToVQUDYADNz7w8QF;_ylu=X3oDMTBrc3VyamVwBHNlYwNzcgRzbGsDdmlkBHZ0aWQD?p=parkinson%27s+disease&vid=38BAB6A5C54BD36B809938BAB6A5C54BD36B8099&l=&turl=http%3A%2F%2Fts4.mm.bing.net%2Fth%3Fid%3DV.4770644278
050823%26pid%3D15.1&rurl=http%3A%2F%2Fvideo.about.com%2Fseniorhealth%2FParkinson-s-Disease.htm&tit=Causes+of+Parkinson%26%2339%3Bs%C2%A0Disease&c=1&sigr=11r9e5spu&fr=yfp-t-521&tt=b
Alzheimers’s Diseasehttp://video.search.yahoo.com/video/play;_ylt=A2KLqINyTYVQyT4ABHv7w8QF;_ylu=X3oDMTBrc3VyamVwBHNlYwNzcgRzbGsDdmlkBHZ0aWQD?p=alzheimers&vid=6D8E980448FDDC46180E6D8E980448FDDC46180E&l=&turl=http%3A%2F%2Fts1.mm.bing.net%2Fth%3Fid%3DV.4630520980111372%26pid%
3D15.1&rurl=http%3A%2F%2Fvideo.about.com%2Falzheimers%2FAlzheimer-s-Disease.htm&tit=Effects+of+Alzheimer%26%2339%3Bs%C2%A0Disease&c=1&sigr=11p0ies6m&fr=yfp-t-521&tt=b
Epilepsyhttp://video.search.yahoo.com/video/play;_ylt=A2KLqICrToVQ5h0ACYz7w8QF;_ylu=X3oDMTBrc3VyamVwBHNlYwNzcgRzbGsDdmlkBHZ0aWQD?p=epilepsy&vid=8FD54097CA0480952C218FD54097CA0480952C21&l=4%3A09&turl=http%3A%2F%2Fts2.mm.bing.net%2Fth%3Fid%3DV.5046595914104921%26p
id%3D15.1&rurl=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3D6NcqQkKjqTI&tit=What+Causes+Epilepsy%3F+%28Epilepsy+%235%29&c=5&sigr=11ais5mk9&fr=yfp-t-521&tt=b
AtaxiaMeningitisHydrocephalusStroke (CVA)ConcussionParalysis paraplegia
 quadriplegia
 hemiplegia
Cerebral PalsySpina BifidaAnencephaly-