INTRODUCTION TO
PSYCHOLOGY
PSY1002
Unit 3: Biological Bases of Behavior
Learning Objectives
Students should be able to:
• Identify the major structures of a neuron
• Identify the roles of neurotransmitters
• Describe the divisions and structures of the brain and
explain their functions
• Identify the divisions of the nervous system
• Explain how hormones released by the endocrine system
affect various body functions
The Nervous System
• This is the body’s
electrochemical
communication
circuitry.
• The human nervous
system is made up of
billions of
communicating nerve
cells
Nervous System
• Is a complex network of interconnected nerve
fibers, that regulate the bodily processes & is
ultimately responsible for all aspects of conscious
experience
• The nervous system is made up of the Central
Nervous System (Brain & Spinal cord) and the (rest
of the Peripheral Nervous system nerves in the
body, including those that cannot connect to the brain
and spinal cord)
Characteristics of the Nervous System
• Complexity: orchestration of BILLIONS of nerve cells to
work together in order for simple actions
• Integration: the brain is named the “great integrator”,
meaning it does a wonderful job of pulling info together
• Adaptability: world around us is constantly changing,
the brain & NS together serve as our agent for adapting
to the world… “plasticity” is the brain’s special capacity
for change
• Electrochemical Transmission: brain & NS function
essentially as an information- processing system
powered by electrical impulses and chemical
messengers
Nervous System:
Peripheral Nervous System
• The Peripheral Nervous
System is, itself, made up of
the Somatic Nervous System
and the Autonomic Nervous
System
• Somatic/ voluntary Nervous
System connects nerves fibers
to voluntary muscles &
provides the brain w/ feedback
• Autonomic/ Involuntary
Nervous System connects the
CNS to all internal organs
which people do not
customarily control
Nervous System
• Regulation of the Autonomic Nervous system occurs via the
Sympathetic Nervous System and the Parasympathetic
Nervous System
• Sympathetic NS prepares the body to respond to emergencies,
such as strong emotions/ strenuous activity. It is concerned w/ the
mobilization & exertion of energy.
• Parasympathetic NS controls the activities of the organs under
normal circumstances and acts antagonistically to the Sympathetic
NS
• When an emergency has passed, this NS helps to restore the
body to a normal state
• It is concerned with conservation of body energy
Pathways in the Nervous System
• NS has specialized pathways that are adapted for
different functions
• Afferent Nerves: also called sensory nerves,
nerves that carry information about the external
environment to the brain and spinal cord via
sensory receptors
• Efferent Nerves: also called motor nerves, nerves
that carry information OUT of the brain and spinal
cord to other areas of the body
Pathways in the Nervous System
Summary of Nervous System
Nervous System
• How does information from
“outside” get “inside” and trigger
your emotions and behavior?
• Answer: NEURONS
Nervous System : Neuron
• Neuron: cells within our
bodies that are
specialized for the task
of receiving, moving &
processing on
information
• They are the basic
building blocks of the
nervous system
Nervous System : Parts of the Neuron
• Cell Body: contains the nucleus and provides the life
processes for the cell
• Axon: carries information FROM the cell body to the
terminal buttons
• Dendrites: RECIEVES information from the terminal
buttons from another neuron
• Terminal Buttons: forms a synapse with another
neuron & sends information to that neuron
Flow of information along the Neuron
Dendrite =>Cell Body => Axon=> Terminal Buttons
Neurochemical Messengers
• Neurochemistry is the chemical processes that occur in the brain
and nervous system.
• By sending messages with neurotransmitters to signal various cell
activities, brain perform its functions.
• Neurotransmitter spreads chemical messages from neuron to
neuron to broadcast certain work and thus it works.
The are 7 major neurochemical messengers;
• GABA
• Acetylcholine
• Glutamate
• Norepinephrine
• Oxytocin
• Dopamine
• Serotonin
Neurochemical messengers
• Acetylcholine: usually stimulates the firing of neurons and is
involved in muscle action, learning and memory. Persons with
Alzheimer disease is found to have a deficiency in
acetylcholine
• GABA (gamma aminobutyric acid): is found throughout the
Central Nervous System. GABA plays a key function in the
brain in inhibiting many neurons from firing. It’s the brain’s
brake pedal. Low levels of GABA is linked with anxiety.
• Glutamate: is a powerful excitatory neurotransmitter that is
released by nerve cells in the brain. It is responsible for
sending signals between nerve cells, and under normal
conditions it plays an important role in learning and memory.
Neurochemical messengers
• Norepinephrine: stress stimulates the release of another
of the body’s neurotransmitters. It inhibits the firing of
neurons in the CNS, but it excites the muscles, heart,
intestines and urogenital tract. Too little is associated with
depression, too much is associated with agitated states.
• Dopamine: helps control voluntary movement and affects
sleep, mood, attention, learning and the ability to
recognize oppurtunities for rewarding experiences in the
environment. Low levels are associated with Parkinsons
disease.
Neurochemical messengers
• Serotonin: is involved in the regulation of sleep, mood,
attention and learning. Lower levels of this is associated with
depression.
• Endorphines: are natural opiates- substances that depress the
NS activity and eliminate pain- that mainly stimulate the firing of
neurons. As opiates, endorphines shield the body from pain
and elevate feelings of pleasure
• Oxytocin: is a hormone and a neurotransmitter that plays an
important role in the experience of love and bonding. A
powerful surge of oxytocin is released in mothers who have just
given birth. It is also associated with the onset of lactation. It is
also released as part of sexual orgasm and is thought to figure
in the human experience of orgasmic pleasure and emotional
attachment to romantic partners
CENTRAL NERVOUS
SYSTEM
Central Nervous System
• Consists of the Brain and the Spinal Cord
• Spinal Cord has 2 major functions;
• Carries sensory info. via Afferent (sensory) nerve fibers
from receptors throughout the body to the brain; &
conducts info. via Efferent (motor) nerve fibers & glands
• Plays a key role in various reflexes
Lobes of the Brain
Central Nervous System:
Brain: Frontal Lobe
 In charge of emotions,
reasoning, planning,
movement and parts of
speech
 Useful in purposeful
acts, creativity,
judgment, problem
solving
 Damage to this area
results in less control
over fine movements,
esp. in the fingers
Central Nervous System
Brain : Parietal Lobe
In charge of processing
nerve impulses related to
the senses, and language
functions
Damage to the left side
(hemisphere) may cause
impairments in the ability to
read, write, or the individual
may have difficulty knowing
where parts of their own
body are located
Damage to the right
hemisphere may cause
individuals to become
unaware of the left side of
the body
Central Nervous System
Brain: Occipital Lobe
• Responsible for vision
and the ability to
recognize objects
• Damage to this area
often produces a ‘hole’ in
the person’s field of
vision (what you are able
to see)
• Damage to the right side
produces loss of vision
in the left field and vice
versa
Central Nervous System
Brain: Temporal Lobe
• Hearing & memory,
meaning & language,
plays a role in emotion &
learning. Interpreting and
processing auditory stimuli
• Damage to the right
hemisphere may impair
one’s ability to understand
organizations of sound
such as melodies &
sounds
• Damage to the left side
affects one’s ability to
recognize/ understand
spoken word
Central Nervous System : Brain
Cerebral Hemispheres & Split- Brain
Research
• Broca’s aphasia was
discovered by Paul Broca
(1861), he saw a patient who
had received injury to the left
side of his brain 30 years
earlier. He suffered from a
language disorder that
involved the inability to produce
language.
• Wernicke’s aphasia was
discovered by Carl
Wernicke(1874), a German
neurologist, who realized
patients with damage to the left
hemisphere had difficulties
understanding language.
Regions of the Brain
Has 3 regions:
 Forebrain
 Midbrain
 Hindbrain
Regions of the Brain: Forebrain
• By far the largest region
of your brain is the
forebrain
The human forebrain’s
most important structures
are the:
• limbic system
• Thalamus
• basal ganglia
• Hypothalamus
• cerebral cortex
Regions of the Brain: Forebrain
Cerebrum
• When you picture the iconic shape of
the human brain, the majority of
what’s visible is the cerebrum with its
wrinkly, pinkish-grey outer
appearance.
• It makes up around 85% of the brain
and consists primarily of grey matter,
divided into two hemispheres.
• The cerebrum is where most of
the important brain functions
happen, such as thinking,
planning, reasoning, language
processing, and interpreting and
processing inputs from our
senses, such as vision, touch,
hearing, taste and smell.
Diencephalon
• Apart from the cerebrum,
the forebrain also contains
several small, but highly
important structures located
towards the centre of the
brain and are included in
the limbic system.
• Collectively these are called
the diencephalon and they
are involved in regulating
things like the body’s
sensory perception, motor
functions, and hormones.
Regions of the Brain: Forebrain
Thalamus
• It is a prime processing
centre for sensory
information, as it links up
the relevant parts of the
cerebral cortex with the
spinal cord and other
areas of the brain
important for our senses.
• The thalamus also
controls sleep.
Hypothalamus
• The hypothalamus is quite small,
only about the size of an almond.
• It can be found right underneath
the thalamus, and despite its
small size it is actually the major
control centre of the autonomic
motor system.
• It is involved in some hormonal
activity and connects the
hormonal and nervous systems.
• The hypothalamus also works to
regulate things like our blood
pressure, body temperature, and
overall homeostasis.
Regions of the Brain: Forebrain
Pineal Gland
• The pineal gland is even
smaller than the hypothalamus
- only about the length of a
grain of rice - and is tucked
between the two lobes of the
thalamus.
• It is actually shaped like a tiny
pinecone, and its main job is to
produce the hormone
melatonin, which regulates our
sleep-wake cycles.
• Just like the hypothalamus, it is
also involved in regulating
hormonal functions.
Regions of the Brain
Forebrain
(Diencephalon & Telencephalon)
• Thalamus: serves as a
relay station, it sorts
information and sends
it to the appropriate
places in the brain for
further integration and
interpretation
• Basal ganglia: works
with the cerebral cortex
and the cerebellum to
control and coordinate
voluntary movements
Regions of the Brain
Forebrain
(Diencephalon & Telencephalon)
• Hypothalamas: it
monitors 3 rewarding
activities- eating,
drinking, sex- as well as
emotion, stress and
reward. It also helps
direct the Endocrine
system
• Cerebral cortex:
responsible for higher
order intelligence,
memory & personality
such as thinking,
planning, reasoning &
memory
Limbic System
• Structures that border the
midline of the brain
• Plays an important role
in stress & emotional
responses
• Its 2 main parts are the
amygdala (discrimination
of objects vital for
survival) & hippocampus
(storage of memories)
Regions of the Brain
Hindbrain
(Medulla, Pons, Cerebellum)
• It is the lowest portion
of the brain
• Main parts: medulla,
pons, cerebellum
• Medulla: begins where
the spinal cord enters
the skull. It controls
many vital functions,
such as breathing,
heart rate and
regulates our reflexes
Regions of the Brain: Midbrain
Regions of the Brain
Midbrain
• Is the major pathway for sensory
and motor impulses moving
between the forebrain and the
hindbrain
• The midbrain relays information
between the brain and the eyes
• It is also responsible for the
coordination of visual and auditory
reflexes
• Parkinson disease damages a
section near the bottom of the
midbrain, causing deterioration in
body movement, rigidity, and
tremors
Regions of the Brain: Hindbrain
• It includes most of the
brainstem and a dense coralshaped structure called the
cerebellum.
• The brainstem is one of the
most important parts of the
entire central nervous
system, because it connects
the brain to the spinal cord
and coordinates many vital
functions, such as breathing
and heartbeat.
• There are three main parts of
the hindbrain - pons,
cerebellum, and medulla
oblongata
Regions of the Brain
Hindbrain
(Medulla, Pons, Cerebellum)
• Pons: is the bridge in
the hindbrain that
connects the
cerebellum and the
brain stem. It contains
several clusters of
fibers involved in sleep
and arousal
• Much of the hindbrain
is the BRAIN STEM
Regions of the Brain
Hindbrain
(Medulla, Pons, Cerebellum)
• Cerebellum: extends from the rear of the
•
•
•
•
hindbrain, it plays an important role in
motor coordination
The cerebellum coordinates our
sensations with responses from our
muscles, enabling most of our voluntary
movements.
It also processes nerve impulses from
the inner ear and coordinates them with
muscle movement, thus helping us
maintain balance and posture.
Damage to the cerebellum impairs
coordinated movements, people’s
movements are often awkward and jerky
Extensive damage makes it impossible to
stand up
Regions of the Brain: Hindbrain
Medulla Oblongata
• The lower part of both the
brainstem and the overall
hindbrain is the medulla
oblongata, where the brain
transitions to the spinal cord.
• It is only about 3cm long, but
the medulla is an
indispensable nerve tract
which contains the control
centres for our autonomic
vital functions - heart rate,
blood pressure, breathing and many involuntary
reflexes such as swallowing
and sneezing.
Regions of the Brain: Summary
ENDOCRINE SYSTEM:
KEY TERMS
Endocrine system
Glands
Hormones
Pituitary gland
Adrenal glands
Pancreas
Endocrine System
• The body system consisting of a
set of glands that regulate the
activities of certain organs by
releasing their chemical products
into the bloodstream
• Responsible for chemical
regulation of bodily processes
• Endocrine glands release
chemicals called hormones
directly into the blood stream
• These hormones exert profound
effects on a wide range of
processes related to basic bodily
functions
Endocrine System
• Glands: organs/ tissues in the body that create chemicals
that control many of our bodily functions
• Hormones: chemical messengers that are produced by
the endocrine glands and carried by the bloodstream to all
parts of the body
Endocrine System
• Pituitary Gland: a pea- sized gland just beneath the
hypothalamus that controls growth and regulate other
glands
• Adrenal glands: glands at the top of each kidney that
are responsible for regulating moods, energy level,
and the ability to cope with stress
• Pancreas: a dual- purpose gland under the stomach
that performs both digestive and endocrine functions
GENETICS & BEHAVIOR TO
BE DISCUSSED IN TUTORIAL
SESSION
GENETICS & BEHAVIOR
Genetics
• In addition to the brain & NS, other aspects of physiology
also have consequences for physiological processes
• Within the human body are literally trillions cells
• The nucleus of each human cell contains 46
chromosomes
Genetics
• Chromosomes: in the human cell, threadlike structures
that come in 23 pairs, 1 member of each pair originating
from each parent and that contain remarkable
substance DNA
• Deoxyribonucleic acid (DNA): a complex molecule in the
cell’s chromosomes that carries genetic information
• Genes: the units of hereditary information consisting of
short segments of chromosomes of DNA
The study of Genetics
Dominant- recessive gene
principle:
• the principle that if 1 gene
of a pair is dominant and
1 is recessive, the
dominant gene overrides
the recessive gene. A
recessive gene exerts its
influence only if both
genes of a pair are
recessive
Selective breeding
• : is a genetic method in
which organisms are
chosen for reproduction
based on how much of a
particular trait they display
• Behavior genetics: is the
study of the degree and
nature of heredity’s
influence on behavior eg.,
twin studies
The study of Genetics
Behavior genetics
• is the study of the degree and
nature of heredity’s influence
on behavior e.g.., twin
studies, identical twins vs
fraternal twins
• Seeks to answer the
question: to what extent are
our abilities, personality traits,
sexual orientations,
sociability, and psychological
disorders determined by
genes inherited from our
parents?
Twin Studies
• Twin studies are used to help
answer the questions
• Because identical twins share
the same genetic makeup, we
can assume that differences
between them are due to
environmental factors
• Reflection: do you thing Twin
Study is a reliable way to test
whether our behavior is
determined more by nature
(genetics) or nurture
(environment)? Why or why
not?
Nature vs. Nurture
• To what extent is development shaped by our genes
(Nature) and to what extent is it a reflection of the
impact of our experiences and the world around us
(Nurture) ?
• Nature: as individual’s biological inheritance, especially
his or her genes
• Nurture: an individual’s environmental and social
experiences
Nature vs Nurture Debate
Nature
• We genetically inherit
physical traits from our
parents, but we also
inherit personality traits,
intelligence, and
preferences
Nurture
• The household and city
we grew up in, how we
were raised by our
parents, teachers and
friends• These are environmental
factors that determine
who we are
Nature vs Nurture Debate: Common
Points
Nature
• Studies show that we
inherit genes that are
related to certain
personality traits
Nurture
• Often Identical twins grow
up to have very different
personality and
preferences