THE CENTRAL NERVOUS SYSTEM
CH 7
I.
Overview of the nervous system
A. Parts of the Nervous System
The nervous system
Has two parts
Central
peripheral
Nervous
nervous
System
system
Made of
made of
Brain and spine
all other nerves
B. Overview of How the Nervous
System Works
 Receptors in sense organs pick
up info from environment
 They send info to sensory
neurons in the peripheral
nervous system
 Sensory neurons send info to
brain /spine in central nervous
system
 Interneurons of the central
nervous system processes the
info and sends it to motor
neurons in peripheral nervous
system
 Motor neurons activate
muscles to contract
C. Structure of a Neuron
dendrites
Cell body
axon
Axon terminal
Collateral branch
Presynaptic cell
Postsynaptic cell
Dendrites: receive info from sense
receptors or other neurons
Cell body: contains all the organelles
Axon: send info to other neurons or to
muscle cells
Axon terminals: where the neuron comes
in contact with the next cell
Synapse: the gap between 2 cells where
the neuron communicates with another
cell
Presynaptic cell: the cell sending the info
Post synaptic cell: the cell receiving the
info
D. Anatomical classes of Neurons
Unipolar
neuron: sense
neurons that
send info to CNS
are unipolar
Bipolar neuron:
rare and found
in sense organs
Multipolar
neuron: motor
neurons that
receive info from
CNS are
multipolar
E. Neuroglia of the CNS: cells that
support and protect the neurons
of the CNS
 Ependymal cells: line the fluid
filled cavity that the brain and
spine sit in. This cavity has
cerebrospinal fluid
 Microglia: cells that get rid of
waste and foreign invaders
from the CNS
 Oligodendrocytes: make
myelin that forms myelin
sheath
o Myelin sheath: speeds up
the transmission of nerve
impulses
F. Neuroglia of the PNS:
 Schwann cells: form a sheath
around the axons of peripheral
neurons
 Satellite cells: surround cell
body of peripheral neurons
II. How the Nervous System Sends
Information
 Resting Membrane potential:
the difference in charge between
the inside of the neuron and its
surrounding environment
 When the neuron is stimulated
it disrupts this resting
membrane potential sending a
“wave” down the neuron called
the action potential
 The action potential starts in the
dendrites, moves through the cell
body, and down the axon
 When the action potential reaches the
end of the axon, neurotransmitters are
released into the synapse and start the
action potential in the next neuron
 http://highered.mcgrawhill.com/sites/0072943696/student_view0/chapter8/animation__the_nerve_im
pulse.html
http://highered.mcgrawhill.com/sites/0072943696/student_view0/chapter8/animation__chemical_synapse__quiz_2
_.html
III. Anatomy of the CNS
A. The Main Parts of the Brain
cerebrum
diencephalon
midbrain
cerebellum
pons
Medulla oblongata
 Cerebrum: highly convoluted.
Involved in conscious thought,
memory storage and processing,
sensory processing, regulation of
skeletal muscle
 Cerebellum: involved in coordinating
the motor commands from the
cerebrum
 Midbrain: processes visual and
auditory stimuli. Controls reflexes
 Pons: connects cerebellum to brain
stem
 Medulla oblongata: regulates
breathing, heart rate, and digestive
system activities
B. The Parts of the Cerebrum
Parietal lobe
Frontal lobe
Occipital lobe
Temporal lobe
 Frontal lobe: reasoning, planning,
problem solving, speech
 Parietal lobe: movement,
orientation, recognition, perception
 Occipital lobe: visual processing
 Temporal lobe: auditory perception
memory, speech
http://www.youtube.com/watch?v=Vy8
EvyQoQIE
C. What protects the brain?
 Bones of the cranium
 Cerebrospinal fluid: the fluid
that surrounds the brain and
spine
 Cranial meninges: connective
tissue that separates the
cranium from the brain and
contains the cerebrospinal fluid
D. The Cerebrum has 2
hemispheres
 Each hemisphere controls specific
functions not performed by the other
hemisphere
 The two hemispheres are connected
by the corpus callosum
 The right visual field is in left
hemisphere
 The motor cortex that controls left
hand is larger in right hemisphere
 Are left handed people more artistic
and right handed people more
analytical?
IV. The Spinal Cord
 Contains the nerves that control the
body
 At various points on the spinal cord,
a pair of spinal nerves branches off
 Each pair of spinal nerves controls a
different part of the body
 There are 31 pairs of spinal nerves