1. Human Biology Sylvia S. Mader Michael Windelspecht
Chapter 13
Nervous System
Lecture Outline
Part 1
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2. Nervous System
See separate FlexArt PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes 2

3. Points to ponder What are the 3 types of neurons? What are neuroglia?
What is the structure of a neuron?
What is the myelin sheath? Saltatory conduction? Schwann cell? Node of Ranvier?
Explain the resting and action potential as they relate to a nerve impulse.
How does the nerve impulse traverse the synapse?
What are the 2 parts of the nervous system?
What 3 things protect the CNS?
What are the 4 parts of the brain and their functions?
What is the reticular activating system and the limbic system?
What are some higher mental functions of the brain?
What are the 2 parts of the peripheral nervous system?
How do abused drugs work?

4. The nervous divisions 2 divisions
13.1 Overview of the Nervous System
The nervous divisions
2 divisions
__________________ (CNS): Brain and spinal cord
__________________ (PNS): Nerves and ganglia (collections of cell bodies)

5. The nervous divisions 13.1 Overview of the Nervous System
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brain
Central Nervous System (CNS)
cranial nerves
brain
spinal cord
spinal cord
spinal nerves
Peripheral Nervous System (PNS)
sensory (afferent) nerves —
carry sensory information
into brain and spinal cord
motor (efferent) nerves —
carry motor information
from CNS to effectors
somatic sensory
nerves: signals
from skin,
muscles,
joints, special
senses
somatic motor
nerves: signals
to skeletal
muscles,
voluntary
autonomic motor
nerves: signals
to smooth
muscle, cardiac
muscle, glands,
involuntary
visceral sensory
nerves:
signals from
body organs
sympathetic
division
“fight or flight”
parasympathetic
division
“rest and digest” a. b.
Figure The two divisions of the nervous system.

6. 13.1 Overview of the Nervous System
The nervous system allows for _____________ between cells through sensory input, integration of data, and motor output.
2 cell types: _______ and ________

7. Expanding on neurons 3 types of neurons
13.1 Overview of the Nervous System
Expanding on neurons
3 types of neurons
_________ – takes impulses from sensory receptor to CNS
_________ – receives information in the CNS and sends it to a motor neuron
______ – takes impulses from the CNS to an effector (i.e., gland or muscle fiber)

8. Expanding on neurons Neuron structure (Ch. 4 review)
13.1 Overview of the Nervous System
Expanding on neurons
Neuron structure (Ch. 4 review)
Cell body – main cell where nucleus and most organelles reside
Dendrites – many short extensions that carry impulses to a cell body
Axon (nerve fiber) – single, long extension that carries impulses away from the cell body

9. Types of neurons 13.1 Overview of the Nervous System
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a. Sensory
neuron
sensory
receptor
cell body
axon
myelin
sheath
direction
of conduction
Schwann
cell
b. Interneuron
400 nm
axon
dendrite
c. Motor neuron
cell body
axon
node of Ranvier
2.7 μm
Figure The structure of sensory neurons, interneurons, and motor neurons.
axon terminal
direction
of conduction
a (myelin): © M.B. Bunge/Biological Photo Service; c (cell body): © Manfred Kage/Peter Arnold/Photolibrary

10. 13.1 Overview of the Nervous System
The myelin sheath
A lipid covering on long axons that acts to increase the speed of nerve impulse conduction, insulation, and regeneration in the PNS
_____________ – neuroglia that make up the myelin sheath in the PNS
_____________ – gaps between myelination on the axons
Saltatory conduction – conduction of the nerve impulse from node to node

11. Neuron structure 13.1 Overview of the Nervous System
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
a. Sensory
neuron
sensory
receptor
cell body
axon
myelin
sheath
direction
of conduction
Schwann
cell
b. Interneuron
400 nm
axon
dendrite
c. Motor neuron
cell body
axon
node of Ranvier
2.7 μm
Figure The structure of sensory neurons, interneurons, and motor neurons.
axon terminal
direction
of conduction
a (myelin): © M.B. Bunge/Biological Photo Service; c cell body): © Manfred Kage/Peter Arnold/Photolibrary

12. The nerve impulse: Resting potential (RP)
13.1 Overview of the Nervous System
The nerve impulse: Resting potential (RP)
___________________ – when the axon is not conducting a nerve impulse
More positive ions outside than inside the membrane
Negative charge of -70 mV inside the axon
More Na+ outside than inside
More K+ inside than outside

13. The nerve impulse: Resting potential (RP)
13.1 Overview of the Nervous System
The nerve impulse: Resting potential (RP)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
recording
electrode
inside axon
reference
electrode
outside axon + + + + + + + + + +          
axonal
membrane           + + + + + + + + + +
inside axon K+
Na+
gated K+
channel
gated Na+
channel
outside axon
a. Resting potential: Na+ outside the axon, K+ and large anions inside the axon. Separation of charges polarizes the cell and causes the resting potential.
Figure 13.3a Generation of an action potential.

14. The nerve impulse: Action potential
13.1 Overview of the Nervous System
The nerve impulse: Action potential
________________ – rapid change in the axon membrane that allows a nerve impulse to occur
Sodium gates open, letting Na+ in.
Depolarization occurs.
Interior of axon loses negative charge (-55 mV, then +35 mV).

15. The nerve impulse: Action potential
13.1 Overview of the Nervous System
The nerve impulse: Action potential
Potassium gates open, letting K+ out.
_______________ occurs.
Interior of axon regains ______________ charge (-70 mV).
Wave of depolarization/repolarization travels down the axon.
Resting potential is restored by moving potassium inside and sodium outside.