Class PPT of the Nervous System

1. NERVOUS SYSTEM
Your
Getting
on My
Nerves!

2. NERVOUS SYSTEM
• Interpreting, processing and transferring
information

3. Across Species
• Lets look at some different organisms and
how their nervous system is oriented.
• Try to focus on structure and function… What
the organism looks like, where/how it lives

4. Simple Centralized
Gastrovascular
Organism cavity. No
only a few complex method
cells thick to deliver ions for
nervous system
Simple
Organism…
Sessile NO need for
complex skeletal Simple nervous
movements system

5. Can learn to
Ganglia:
Group of change responses
nervous tissue Due to stimuli
Cephalization
Eyespots to
Slightly more
sense light complex organism…
and detect with a slightly more
specific complex Nervous
system
chemicals

6. Larger more
complex organism
than the Primitive
Planarian… More
complex system
Brain
Multiple
Ganglia
throughout
body for more
complex
responses and
coordination

7. Larger more
complex
organism…
Larger more
complex
system
Developed
sensory organs
Must have a
more developed
LARGE Axons
extending from system to process
brain tissue information

8. Molecular Components of Neural
Communication
NEURON: a cell of the nervous system

9. PARTS OF A NEURON
• Cell Body : Nucleus and Organelles of the
neuron… if it dies the neuron dies… FOREVER
• Axon: The SENDING end of a neuron
– Axon hillock: Signal generation site of an axon
– Synaptic Terminals: Where neurotransmitters are
stored and expelled into the synapse
• Dendrites: The RECEIVING end of a neuron
• Synapse: The space between communicating
neurons

10. Details of a Nervous Signal
• Nervous system connects all body systems
and functions with ion exchanges and
neurotransmitters to make its point

11. Every cell has a voltage, or
membrane potential, across its
plasma membrane
• A membrane potential is a localized electrical
gradient across membrane.
– Anions are more concentrated within a cell.
– Cations are more concentrated in the extracellular
fluid.
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12. • How a Cell Maintains a Membrane Potential.
– Cations.
CELLS HAVE TO BE
• K+ is the principal intracellular cation.
• Na+ is the principal extracellular cation.
NEGATIVE…
DUH…
– Anions.
DNA ISamino acids, sulfate, and phosphate are the
• Proteins, NEGATIVE!
principal intracellular anions.
CELLSthe principal extracellular anion.
• Cl is
HAVE DNA!!
–
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13. • Ungated ion channels allow ions to diffuse
Sodium-Potassium
across the plasma membrane.
pump-channels are always open.
– These A protein pump
found mainly in the
• This diffusion does not achieve an equilibrium
since the sodium-potassium pump transports
nervous system that
these ions against their +
concentration gradients.
ACTIVELY pumps K INTO
a cell and Na + OUT
Fig. 48.7
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14. • Hyperpolarization.
– Gated K+ channels open
K+ diffuses out of the
cell the membrane
potential becomes more
negative.
More K+ INSIDE the cell
Can leadthe gates open
When to INHIBITION
NOT wanting the neuron to
K+ Rushes OUTWARD
FIRE
Because of the concentration
LosingOr reach the
the + makes
Inside more -
POTENTIAL
Fig. 48.8a
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15. • Depolarization.
– Gated Na+ channels open
Na+ diffuses into the
cell the membrane
potential becomes less
negative.
Again due to
concentration
Differences… Na+ rushes
INWARD causing the
Cell to become more
POSITIVE Fig. 48.8b
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16. • The Action Potential:
All or Nothing
Depolarization.
– If graded potentials
Once enough Positive ions
sum to -55mV a
threshold potential is
change the membrane
achieved.
potential Enough…
• Thisthe Axon will
triggers an action
potential.
FIRE
– Axons only.
Sending a cascading ionic
Electrical current…
ACTION POTENTIAL 48.8c
Fig.
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17. • Step 1: Resting State.
Fig. 48.9
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18. • Step 2: Threshold.
Fig. 48.9
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19. • Step 3: Depolarization phase of the action
potential.
Fig. 48.9
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20. • Step 4: Repolarizing phase of the action
potential.
Fig. 48.9
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21. • Step 5: Undershoot.
Fig. 48.9
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22. Click on image to
play video 
Fig. 48.10
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23. • Schwann cells are found within the PNS.
– Form a myelin sheath by insulating axons.
Fig. 48.5
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24. • Saltatory conduction.
– In myelinated neurons only unmyelinated regions of
the axon depolarize.
• Thus, the impulse moves faster than in unmyelinated
neurons.
Fig. 48.11
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25. Chemical or electrical
communication between cells occurs
at synapses
• Electrical Synapses.
– Action potentials travels directly from the presynaptic
to the postsynaptic cells via gap junctions.
• Chemical Synapses.
– More common than electrical synapses.
– Postsynaptic chemically-gated channels exist for ions
such as Na+, K+, and Cl-.
• Depending on which gates open the postsynaptic neuron
can depolarize or hyperpolarize.
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26. CLICK
ME!

27. Fig. 48.12
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28. Neural integration occurs at the
cellular level
• Excitatory postsynaptic potentials (EPSP)
depolarize the postsynaptic neuron.
– The binding of neurotransmitter to postsynaptic
receptors opens gated channels that allow Na+ to
diffuse into and K+ to diffuse out of the cell.
• Inhibitory postsynaptic potential (IPSP)
hyperpolarizes the postsynaptic neuron.
– The binding of neurotransmitter to postsynaptic
receptors open gated channels that allow K+ to
diffuse out of the cell and/or Cl- to diffuse into the
cell.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

29. • Summation: graded potentials (EPSPs and IPSPs)
are summed to either depolarize or
hyperpolarize a postsynaptic neuron.
Fig. 48.14
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

31. NEUROTRANSMITTERS
Released by the PRESYNAPTIC cell to cause
an affect on the POSTSYNAPTIC cell
• Acetylcholine: Most studied in the
muscular response, but also in Memory
formation and learning. Causes an excitatory
response in muscle cell.
Homeostasis… feedback
• Acetyl cholinesterase hydrolyzes Acetylcholine
terminating the excitatory response.
Otherwise your muscles would
Contact out of control!!!

32. Botox is aQUESTION prevents
neurotoxin that
vesicles containing acetylcholine
from being released into the
• If I told you BOTOX was a neurotoxin that
synapse. The vesicles are unable to
disrupted the function of Acetylcholine…
connect to the cell membrane to
WHAT DOES THAT MEAN???
release their contents
Ach cannot cause a contraction of
The muscle.
Muscles relax and wrinkles fade.
And EYEBROWS do not move for 3-4
months!

33. DOPAMINE and SEROTONIN
• Made from amino Acids
• Affect sleep, mood, attention and learning
• Treat depression by inhibiting the reabsorption of
Serotonin allowing it to remain in the synapse
longer… PROZAC more serotonin to react, more
HAPPY
• Lack of Dopamine in the brain is associated with
Parkinson’s disease… a degenerative nerve disease
associated with a lack of muscle control
LSD & L-dopa (derivative) can doc with the
VIDEO ATTACHED!
dopamine receptors

34. Click boy
PAIN Neurotransmitters
• Substance P (a neuropeptide)- “P FOR PAIN!”
This neurotransmitter allows you to feel PAIN!
Nocieptors- dendrites that receive noxious
thermal, mechanical or chemical PAIN
information.
• Endorphins – This neurotransmitter diminishes
pain.
– Opiate, Morphine and heroin mimic Endorphins…
Similar shape, can doc with the endorphin receptor
to cause euphoria. They also increase urine output.

35. THINKING IT THROUGH
• You have now had several examples of
different neurotransmitters and their
function in the body.
• Take a moment to discuss how some
medicines are made. Be sure to document
your answer in your notes

36. NERVOUS SYSTEM organization
1. Central nervous system
a. Brain : Processing center
b. Spinal cord : sending and receiving
2. Peripheral nervous system
a. Somatic (Motor) : voluntary (except
REFLEX)
b. Autonomic : involuntary

39. How is this regulation AUTONOMIC NS
• The Autonomic nervous system is further
Efficient?
divided into Sympathetic and Parasympathetic
What do you notice
about the
relationship
between the 2
divisions?
Which one would
be activated when
you are being
chased by the
Boogie man

40. AUTONOMIC NS
• The 3rd division: Enteric
– Control of smooth muscles (digestion), Cardiac
muscles and glands

41. HOW is a reflex efficient?
HOW is it protective?

42. Synapse Nociceptor
WHY THIS DIAGRAM IS MISLEADING
OUCH!
Sensory neuron
EFFICENT
1. Interneuron are
2. The sensory neuron
Cross Section of REGULATION! One
Spinal cord primarily INHIBITORY
ALSO sends a message
stimulus… 2
to the brain…thejust
responses… It
They inhibit theSAME
takes longer… which is
sensory nerve can
antagonistic muscle group.
Interneuron
why there is aone muscle
stimulate second or
twowhile inhibiting the
that your burn
other!
doesn’t hurt
Take a moment to describe the
Interneurons typically release
neurotransmitter Muscle
GABA… which is
Motor Neuron inhibitory
what happens in a reflex in contraction
your notes