CENTRAL NERVOUS SYSTEM,

PERIPHERAL NERVOUS SYSTEM &

NEURONS:
STRUCTURE & FUNCTION

CHAPTER 4
 CHAPTER OVERVIEW
Coming up within the chapter

 The CNS and PNS

 The role of the neuron as the primary unit of the nervous system
 Using our senses
 ASSESSMENT
unit 1: how are behavioral & mental processes shaped?
area of study 1

 SAC 1 : resea rc h met hods, t he br a in & it s func t ions

w e e k 4 , s t a r t i n g 2 2 nd Fe b ( T B C )
 Student practical activities logbook completed

Note S/N work requirements

If you are away during a SAC – you
MUST hand in an original medical  glossary
certificate in order to re sit the SAC.  workbook – these will be collected at the end of each chapter (min. 80%
completed).
This is a VCCA requirement, and
 80% attendance rate VCAA requirement
parents or students who only phone
or email do not satisfy this
requirement, and if a medical
certificate is not produced, a score of 0
will be given
• the basic structure and function of the central and PSYCHOLOGY
peripheral nervous systems as communication UNIT 1
systems between the body’s internal cells and organs 2016 – 2020
and the external world
• the role of the neuron as the primary functional unit S T U DY
of the nervous system
D E S I G N D OT
POINTS
C OV E R E D
WITHIN THIS
CHAPTER
 CNS & PNS
• The human brain does not act in isolation. It needs to receive information from the
body’s sense organs (the eyes, ears, skin, nose and tongue) and is also connected with
the muscles and glands in the body so that an organism is able to respond to and act
on the environment.
• There are two major divisions of the nervous system
1. the central nervous system (CNS)
2. the peripheral nervous system (PNS)
• The peripheral nervous system also has two subdivisions: the somatic nervous system
and the autonomic nervous system, which has two branches
– the sympathetic nervous systems
– Parasympathetic nervous systems
 Complete Worksheet INVESTIGATE
TASK
Nervous system data tree
CENTRAL NERVOUS SYSTEM
• The CNS comprises the brain and the spinal
cord.
• The spinal cord runs from the base of the
brain (brain stem), inside the bones of the
spine (vertebrae) to the lower middle
section of the spine.
• It enables the brain to communicate with the
rest of the body by conveying messages from
the brain to the PNS, and from the PNS to
the brain.

• COMPLETE YOUR NERVOUS SYSTEM

COOKIE MAN
 PERIPHERAL NERVOUS SYSTEM
• The peripheral nervous system has two functions:
– To communicate information from the body’s organs, glands and muscles to the CNS, from both the
outside world (such as environmental temperature and sensation on the skin, via sensory neurons)
and the inside world (such as aches and pains)
– To communicate information from the CNS to the body’s organs, glands and muscles, via motor
neurons.
• The peripheral nervous system has two subdivisions:
1. the somatic nervous system: responsible for the voluntary movement of skeletal
muscles and motor neurons communicate messages from the CNS to the particular
muscles that an organism intends to move at any particular moment with Sensory
neurons
2. the autonomic nervous system: responsible for the communication of information
between the CNS and the body’s non-skeletal, internal organs and glands that carry
out the basic bodily functions necessary for survival, such as digestion and
heartbeat.
 SYMPATHETIC & PARASYMPATHETIC
BRANCHES OF THE AUTONOMIC NERVOUS SYSTEM
• The autonomic nervous system is further divided into two branches:
– the sympathetic nervous system
– the parasympathetic nervous system.
• These two systems work together in complementary ways but have different roles.
1. The sympathetic nervous system is like an emergency system that becomes active when
the organism perceives itself to be in danger or in times of stress. It has a survival role because
it readies the body for actions such as running away, fighting the threat, or remaining
(freezing). This is known as the fight, flight or freeze response.
2. The parasympathetic nervous system operates in circumstances where it is relatively
calm. It is responsible for maintaining automatic day-to-day bodily functions such as digestion,
normal heart rate, and normal breathing, the regular bodily functioning, homeostasis, or
returning it to this state.
Basically the sympathetic nervous system prepares the same organs to deal with threats or
stressors, while the parasympathetic nervous system calms it down
EXAMPLES OF THE AUTONOMIC NERVOUS SYSTEM
 Complete the following task REVIEW
and write it down in your QUESTIONS
books

• Review question 4.1 page 8 of

your textbook
AXON VIDEO
 THE ROLE OF THE NEURON AS THE
PRIMARY UNIT OF THE NERVOUS SYSTEM
• Neurons: neurons receive
information from other neurons,
process this information, and then
communicate it to other neurons. In
other words: neurons receive, process
and transmit information to each other.

• Dendrites: receive information from

other neurons or sensory receptors
via synapses and deliver this to the cell
body or soma.
 THE ROLE OF THE NEURON AS THE
PRIMARY UNIT OF THE NERVOUS SYSTEM
• Soma: is the cell body. It is the largest part of the
neuron and controls the metabolism and
maintenance of the cell.

• Axon: is a nerve fibre that carries information

away from the soma to their ends toward other
cells that communicate with the neuron. This
information is referred to as ‘action potential’,
which consists of brief changes in the electrical
charge of the axon. The end of each axon has
terminal buttons that secrete a chemical called a
neurotransmitter whenever information is sent
down the axon in the form of electrical impulses.
 COMMUNICATION BETWEEN NEURONS
• Glial Cells: are not part of the neuron, but have an
important role in supporting neurons. They are also
known as neuroglia, or simply glia, which hold/ing neurons
together. There are four identified functions of glial cells:
1. To surround neurons and hold them in place
2. To supply nourishment and oxygen to neurons
3. To remove dead neurons
4. To insulate one neuron from another and increase the speed
of transmission of nerve impulses. To do this, glial cells
produce myelin.
COMMUNICATION BETWEEN NEURONS
• Myelin is a fatty substance that covers the
axon to insulate it from the surrounding fluid
and from other neurons. It is just the axon
that is covered, not the cell body. Myelin is
produced in the brain and spinal cord by glial
cells.
• The process of producing myelin is called
myelination, where neurons are faster in the
speed of conduction -> the speed in which
messages move through the nervous system
A MORE COMPLEX UNDERSTANDING
OF GILGAL CELLS
Complete Worksheet INVESTIGATE
TASK
Build and label a neuron
 Build a lolly neuron

Soma
Given the
Dendrites
ingredients Myelin
you have been sheath
provided, you
are required Axon
to build a
neuron.

It must include
the following
structures:
Axon
terminals
Activity
Synaptic
buttons
http://www.cidpusa.org/physiology.htm
 USING OUR SENSES
• Our brain and body are in continuous communication with each other. This
communication can be either from our senses to the brain to be interpreted as they
detect incoming information from our environment OR from our brain to our somatic
nervous system (skeletal muscles) so that we respond to our environment.
• Sensory neurons play an important part in our lives by transmitting sensory information
from our environment to our brain.
• Our ability to touch, taste, see, hear and smell all comes from a process beginning with
our sensory neurons registering an external stimulus, and then relaying that information
to the CNS. Motor neurons can then carry signals from the brain and back to the muscle
fibres so that our bodies can respond to the stimulus.
 REACTING TO OUR SENSES
• Our ability to detect stimuli through the sensory neurons gives our brains an
opportunity to consciously respond to hazards in our environment
• Reaction times, of both voluntary and involuntary responses, can be studied in
psychology

Click on the following site to test your reactions time

• http://www.humanbenchmark.com/tests/reactiontime
 REFLEX’S & REFLEX ACTIONS
• Reflex actions are often confused with reactions.
Reflexes are involuntary actions, in response to a
stimulus, that do not involve the brain. They occur
almost instantly when triggered by a certain external
stimulus.

• A reflex arc allows us to react quickly to a stimulus. In

higher-functioning animals, a reflex arc is a neural
pathway in which the sensory neurons send
information immediately to the motor neurons via a
synapse in the spinal cord, known as a relay neuron.
This ability to bypass the brain means reaction time in
reflex actions is much quicker than if our brain had to
process and respond to that stimulus.
 Complete the following task REVIEW
and write it down in your QUESTIONS
books

• Review question 4.3 page 14 of

your textbook
• Test your understanding Q’s on
page 16 of your textbook.