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Module 1.2 Overview of the Nervous
INTRODUCE THE MODULE
Make It Meaningful
(5 minutes) Ask students to
speculate on how their reflexes
influence their everyday behavior
(e.g., reflexes help them to quickly
draw away from a hot stove and to
make the varsity basketball team).
Use their responses for class
discussion as you introduce the
nervous system.
INTRODUCE THE MODULE
Activate Prior Knowledge
(10 minutes) Begin class with
this activity, which asks students
to decide if statements are
true or false. The statements
tap into common beliefs and
misconceptions about psychology.
This activity will benefit students’
understanding of Module 1.2 as
they read.
M1.2: Fact or Falsehood?
Distributed by Bedford, Freeman
Copyright ©
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22 Unit 1 Biological Bases of Behavior
03_HammerTE4e_47547_ch01_2a_163_4pp.indd
System
LEARNING TARGET
1.2-1 Explain the different functions of the nervous system’s main divisions, and
describe the three main types of neurons.
The Nervous System
1.2-1 What are the functions of the nervous system’s main divisions, and what
1.2-1 What ar e the functions of the nervous system’s main divisions, and what
are the three main types of neurons?
are the three main types of neurons?
My [DM’s] nervous system recently gave me an emotional roller-coaster ride. Before send-
nervous system the body’s ing me into a magnetic resonance imaging (MRI) machine for a shoulder scan, the tech-
speedy, electrochemical
communication network, nician asked if I had issues with claustrophobia (fear of enclosed spaces). “No, I’m fine,”
consisting of all the nerve cells I assured her, with perhaps a hint of macho swagger. Moments later, as I found myself on
of the peripheral and central my back, stuck deep inside a coffin-sized box and unable to move, my nervous system had a
nervous systems. different idea. Claustrophobia overtook me. My heart began pounding, and I felt a desperate
central nervous system urge to escape. Just as I was about to cry out for release, I suddenly felt my nervous system
Worth Publishers.
(CNS) the brain and spinal cord. having a reverse calming influence. My heart rate slowed and my body relaxed, though my
peripheral nervous system
(PNS) the sensory and motor arousal surged again before the 20-minute confinement ended. “You did well!” the techni-
cian said, unaware of my emotional roller-coaster ride. What happens inside our brain and
neurons that connect the central body to produce such surging and subsiding emotions? Is the nervous system that stirs us
nervous system (CNS) to the rest
of the body. the same nervous system that soothes us?
Our body’s nervous system is made up of neurons, or nerve cells, that communicate
nerves bundled axons that via chemical messengers called neurotransmitters (see Module 1.3 ). This communication
form neural cables connecting
interneurons neurons within & Worth Publishers. Not for redistribution.
network takes in information from the world and the body’s tissues, makes decisions, and
the central nervous system with
muscles, glands, and sensory sends back information and orders to the body’s tissues ( Figure 1.2-1 ).
organs.
A quick overview: The brain and spinal cord form the central nervous system (CNS) ,
sensory (afferent) neurons the body’s decision maker. The peripheral nervous system (PNS) is responsible for
Bedford, Freeman &
neurons that carry incoming gathering information and for transmitting CNS decisions to other body parts. Nerves are
information from the body’s electrical cables formed from bundles of axons (the neuron extension that passes messages
tissues and sensory receptors to
the brain and spinal cord. to other neurons or to muscles or glands; see Module 1.3 ). Nerves link the CNS with the
motor (efferent) neurons body’s sensory receptors, muscles, and glands. The optic nerve, for example, bundles a mil-
neurons that carry outgoing lion axons into a single cable carrying the messages from the eye to the brain ( Mason &
information from the brain and Kandel, 1991 ).
spinal cord to the muscles and Information travels in the nervous system through three types of neurons. Sensory
glands. neurons carry messages from the body’s tissues and sensory receptors inward (which
has a few million sensory neurons, a few million motor neurons, and billions and billions 15/12/23 9:21 AM
biologists term afferent ) to the brain and spinal cord for processing. Motor neurons
the brain and spinal cord; they
(which are efferent ) carry instructions from the CNS outward to the body’s muscles
communicate internally and
and glands. Between the sensory input and motor output, information is processed via
process information between
interneurons Our complexity resides mostly in these interneurons. Our nervous system
.
the sensory inputs and motor
outputs.
of interneurons.
22 Unit 1 Biological Bases of Behavior
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