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Module 1.3a

information, conducting it
toward the cell body (Poirazi & Figure 1.3-2
Papoutsi, 2020). From there, the Neurons communicating TEACH 1.3-1
cell’s single lengthy axon fiber Our billions of neurons exist in a
vast and densely interconnected
passes the message through web. As part of a fascinating Enrichment
its terminal branches to other electrochemical communication Tell your students that the nodes of
neurons or to muscles or glands process, one neuron’s terminal
(Figure 1.3-2). Dendrites listen; branches send messages to Ranvier are the spaces in between the
neighboring dendrites.
axons speak. myelin sheaths that encircle the axon.
Unlike the short dendrites, These spaces keep the charge going
axons may be very long, pro-
jecting several feet through the David Scharf/Science Source through the long axon. Without the
body. A human neuron carrying nodes of Ranvier, the charge might
orders from the brain to a leg lose its intensity before reaching the
muscle, for example, has a cell
body and axon roughly on the scale of a basketball attached to a rope that’s 4 miles end of the cell.
(6.4 kilometers) long. Much as home electrical wire is insulated, some axons are encased
in a myelin sheath, a layer of fatty tissue that insulates them and speeds their impulses. TEACH 1.3-1
As myelin is laid down up to about age 25, neural efficiency, judgment, and self-control
grow (Nakamura et al., 2018; Van Munster et al., 2015). If the myelin sheath degener- Active Learning
ates, this deterioration leads to diminished control and slower reaction time. In extreme
cases, it results in the disease known as multiple sclerosis. Communication to muscles (One class period) Before you
and brain regions slows. The result: diminished muscle control and sometimes impaired begin discussing the neural impulse
cognition.
Supporting our billions of nerve cells are spidery glial cells (“glue cells”). Neurons are and action potentials, be sure that
Copyright © Bedford, Freeman & Worth Publishers.
like queen bees; on their own, they cannot feed or sheathe themselves. Glial cells are the axon the segmented neuron students understand the parts of a
worker bees. They provide nutrients and insulating myelin, guide neural connections, and extension that passes messages neuron. Use Student Activity: Building
through its branches to other
clean up waste after neurons send messages to one another. Glia also play a role in learning, neurons or to muscles or glands.
thinking, and memory. By “chatting” with neurons, they participate in information trans- myelin [MY-uh-lin] sheath a a Neuron Model to assess their under-
mission and memory (Fields, 2013; Martín et al., 2015). fatty tissue layer segmentally standing of this concept. If you don’t
In more complex animal brains, the encasing the axons of some have an entire class period to devote
proportion of glia to neurons increases. A neurons; it enables vastly greater
postmortem analysis of Albert Einstein’s transmission speed as neural to this activity, have students build
brain did not find more or larger-than- impulses hop from one node to their models outside of class and bring
the next.
usual neurons. However, it did reveal a them to class to share. Remember:
much greater concentration of glial cells glial cells (glia) cells in the
nervous system that support,
than found in the average Albert’s head nourish, and protect neurons; Take time to address any misinforma-
(Fields, 2004). Einstein’s glial cells likely they may also play a role in tion that comes up in this assessment
kept his brain abuzz with activity. learning, thinking, and memory. activity.
action potential a neural
impulse; a brief electrical charge
The Neural Impulse Distributed by Bedford, Freeman & Worth Publishers. Not for redistribution.
M1.3a: Building a Neuron
that travels down an axon.
Neurons transmit messages when stim- Model
ulated by our senses or by neighboring
neurons. A neuron sends a message
by firing an impulse, called the action
potential — a brief electrical charge that Managing multiple sclerosis ENGAGE 1.3-1
travels down its axon. Actor Selma Blair’s multiple sclerosis
results from a loss of the myelin
Depending on the type of fiber, a sheath that insulates her motor axons (15 minutes) To provide a clear
neural impulse travels at speeds ranging and speeds their neural impulses. demonstration of the action poten-
from a sluggish 2 miles (3 kilometers) John Sheerer/Getty Images She has discussed her challenges
openly, including difficulty speaking
per hour to more than 200 miles and walking. In 2018, Blair attended a tial for students, including the role of
(320 kilometers) per hour. But even its Hollywood event using a cane. myelination in neural transmission,
The Neuron and Neural Firing: Neural Communication and the Endocrine System Module 1.3a 29 use the Teacher Demonstration: Using
Dominoes to Illustrate the Action
Potential. This demonstration will help
students better understand neural
03_myersAPpsychology4e_28116_ch01_002_163.indd 29 15/12/23 9:21 AM
transmission and can stimulate class
discussion.
M1.3a: Using Dominoes to
Illustrate the Action Potential

The Neuron and Neural Firing: Neural Communication and the Endocrine System Module 1.3a 29

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