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November 18, 2016
Nervous System Fun Facts
Which “fact” is false?
1) All body functions are controlled and regulated by the
nervous system
2) There are more neurons in the brain then there are stars
in the Milky Way galaxy
3) The left side of the body is controlled by the right side of
the brain and vice-versa
4) The brain reaches maturity at around 25 years of age.
The endocrine system also controls and regulates some body
functions, especially metabolism, growth, and reproduction.
Nervous System Functions
The nervous
system has three
major functions:
1) Sensory input
2) Integration
3) Motor output
Nervous System Functions
1) Sensory input –
the body gathers
information, or
stimuli, from the
internal or
external
environment
Ex) seeing a bright
light
Nervous System Functions
2) Integration– the
body processes
information and
makes a decision
about what should
be done
Example:
“decision” to
initiate flight – orfight response
Nervous System Functions
3) Motor Output–
the body activates
muscles or glands
to effect a
response.
Example: moving
your arm to grab a
chip
Nervous System Functions
Which function(s) are demonstrated in these examples?
 You hear a buzzing sound.
Sensory input
 You weigh the pros and cons of two different
universities, and make a choice. integration
 You move your leg
Motor output
 You touch a hot stove and jerk your hand back.
Sensory input,
integration,
motor output
Nervous System Organization
The nervous system can be organized by structure and by
function.
Nervous System Organization
Structurally, the nervous system is organized into
 The central nervous system,
which consists of the brain and spinal
cord, and which acts to integrate
(interpret & issue instructions for)
stimuli
 The peripheral nervous system which
consists of all the nerves outside the
brain and spinal cord. These receive
stimuli and effect responses in muscles
and glands.
Nervous System Organization
The peripheral nervous system can be further divided into:
1) Afferent or sensory neurons
- bring stimuli to CNS
-- affect the body by internal or external information
2) Efferent or motor neurons
-- carry a signal from CNS
-- cause muscles or glands to
respond
-- effect a change / response
Mneumonic: A comes before E
Nervous System Organization
The efferent / motor neurons can be further divided into:
1) Somatic neurons
- neurons that control
skeletal muscles
- mostly voluntary
2) Autonomic neurons
-- neurons that control
smooth and cardiac
muscle and glands
- involuntary
Nervous System Organization
Determine which parts of the nervous system are involved in
these:
You hear a buzzing sound.
You weigh the pros and
cons of two different
universities, and make a
choice.
You move your leg
You touch a hot stove and
jerk your hand back.
Nervous System Organization
Determine which parts of the nervous system are involved in
these:
You hear a buzzing sound.
You weigh the pros and
cons of two different
universities, and make a
choice.
You move your leg
You touch a hot stove and
jerk your hand back.
Afferent (peripheral) and CNS
Central nervous system
CNS and somatic (efferent, peripheral)
1) Afferent (peripheral)
2) Central nervous system
3) somatic (efferent, peripheral)
Neural Tissue: What do you see?
What do you see?
Researchers
estimate
that the
brain has
10X as many
glial cells as
neurons
But see this
Neuroglia
All nervous tissue cells except neurons are known as
neuroglia, or glial cells. “nerve glue”
CNS Neuroglia
Astrocytes (star-cell)
 Exchange nutrients between blood
and neurons
 protect neurons from harmful
materials.
 “blood brain barrier”
 Control flow of blood through brain
(what is measured in MRI)
 Control extracellular environment
 change shape
 release calcium and ‘glial transmitters’;
uptaking ions and neurotransmitters
 Digest waste
 Moderate the behavior of neurons
Astrocytes are the most abundant
glial cell and may be the cells
responsible for thought
CNS Neuroglia
Microglia
 Shaped like astrocytes, but
smaller, and don’t connect
neurons to blood vessels
 Digest debris, bacteria, and
dead brain cells
Ependymal Cells
 Line the cavities of the brain
and the spinal cord
 Produce and circulate
cerebrospinal fluid
CNS Neuroglia
Oligodendrocytes
 Wrap around axon of CNS
neurons, creating a fatty
myelin sheath that insulates
neurons
 Each oligodendrocyte wraps
around the axons of several
neurons
 Allow for efficient nerve
impulse propagation
Multiple sclerosis (MS) is an
autoimmune disease characterized by
the gradual destruction of the myelin
sheath
Name the cell!
Name the cell!
PNS Neuroglia
Schwann Cells
 Form myelin sheaths around peripheral neuron axons
 Many Schwann cells per neuron
 Give peripheral neurons some ability to regenerate
Satellite Cells
 Surround body of
peripheral neurons
 Function not fully
understood – may
have similar function
as astrocytes??
Think, Pair, Share (5 minutes)
Scholar whose birthday is earlier in the month...
 Identify the two PNS glial cells, determine which cells in
the CNS have similar function, and describe the
similarities and differences in each pair of cells.
Scholar whose birthday is later in the month …
 Identify two similarities and one difference between
astrocytes and microglia
 Explain the location and function of ependymal cells
Oligodendrocytes vs Schwann Cells
Neuron Anatomy
The cell body contains the
nucleus and organelles
Neuron Anatomy
Processes carry information.
• Dendrites receive and
carry messages towards
the cell body.
• The axon generates
messages and usually
carries them away from
the cell body.
• There may be 100’s of
dendrites, but only 1 or 2
axons.
• The end of the axon
branches into 100’s or
1000’s of axon terminals
Neuron Anatomy
Schwann cells wrap around
most PNS axons, forming the
myelin sheath.
Nodes of Ranvier are gaps in the
myelin sheath / spaces between
Schwann cells.
What cells cover the axons of
CNS neurons?
What cells cover the body of
PNS neurons?
Neuron Anatomy
Schwann cells wrap around
most PNS axons, forming the
myelin sheath.
Nodes of Ranvier are gaps in the
myelin sheath / spaces between
Schwann cells.
What cells cover the axons of
CNS neurons? oligodendrocytes
What cells cover the body of
PNS neurons? Satellite cells
Congo Line Review
Write one question that you think might be on an exit
ticket on the front of a note card. It should be
something that can be answered in a sentence or less.
Write the answer on the back.
Homework
Homework:
 Read the two articles and complete the worksheet
Closure
 What were our objectives and what did you learn
about them?
 What was our learner profile trait and how did we
exemplify it?
 How does what we learned today relate to our unit
question and TOK connection.