Psych Chapter 4

Chapter 4
Body and Behavior
Section 1
The Nervous System:
The Basic Structure
How the nervous system works
• Central nervous system (CNS)- the brain
and spinal cord
• Spinal cord- nerves that run up and down
the length of the back and transmit most
messages between the body and brain
• Peripheral nervous system (PNS)- nerves
branching beyond the spinal cord into the
• The long, thin cells of nerve tissue along which messages
travel to and from the brain
• Transmission occurs whenever cells are stimulated past a
minimum point and emit a signal.
• Either fires or
does not fire
Parts of a neuron
• Dendrites- short, thin fibers that protrude
from the cell body
– Receive impulses or messages and send
them to the cell body
• Axon- carries the impulses from the cell
body to the axon terminals
• Axon terminals- release neurotransmitters
to stimulate dendrites of the next neuron
Parts of a neuron
• Myelin sheath- insulates and protects the
axon for some neurons
– speeds the transmission of impulses
– In cases of multiple sclerosis, the myelin
sheath is gone.
The Neuron Connection
• Synapse- the gap that exists between
individual nerve cells
• Neurotransmitters- the chemicals released
by neurons which determine the rate at
which other neurons fire
• Examples of neurotransmitters
– Norepinephrine- is involved with memory and
– Endorphine- inhibits pain
Neuron Activity
• Intensity of neurons depends on how many
other neurons are acting on it
• Afferent neurons- sensory neurons that relay
messages from the sense organs to the brain
(eyes, ears, nose, skin)
• Efferent neurons- motor neurons that send
messages from the brain to the glands and
• Interneurons- process signals, connecting only
to other neurons, not to sensors or muscles
Voluntary and Involuntary activities
• Somatic nervous system (SNS)- the part
of the peripheral nervous system that
controls voluntary movement of skeletal
• Autonomic nervous system (ANS)- the
part of the peripheral nervous system that
controls internal biological functions
Autonomic Nervous System
• Sympathetic nervous system
– Prepares the body for dealing with
emergencies or strenuous activity
• Parasympathetic
– Works to conserve energy and to enhance the
body’s ability to recover from strenuous
Section 2
Studying the Brain
Three parts of the Brain
• Hindbrain- a part of the brain located at the rear
base of the skull that is involved in the basic
processes of life.
• Midbrain- a small part of the brain above the
pons that arouses the brain, integrates sensory
information, and relays it upward
• Forebrain- a part of the brain that covers the
brain’s central core, responsible for sensory and
motor control and the processing of thinking and
Three parts of the Brain
• Includes the following parts:
• Cerebellum
– Helps control posture, balance and voluntary
• Medulla
– Controls breathing, heart rate, and reflexes
• Pons
– Bridge between the spinal cord and brain
– Produces chemicals the body needs for sleep
• Includes the following parts:
• Thalamus
– Integrates sensory input
– “relay station” for all info that travels to and
from the cortex
• Hypothalamus
– Controls functions of hunger, thirst, and
sexual behavior
– Controls the bodies reaction to temperature
• Includes the following parts:
• Cerebral cortex
– Outer layer of the forebrain
• Cerebrum
– Inner layer of the forebrain
– Gives you the ability to learn and store
complex and abstract information
• Limbic system
– Includes various structures that regulate our
emotions and motivations
– Amygdala- controls violent emotions like rage
or fear
– Hippocampus- is important for the formation
of memories
The Lobes of the Brain
• Corpus callosum- a band of fibers that
joins the two sides or hemispheres of the
• Lobes- are the different regions into which
the cerebral cortex is divided
Lobes of the Brain
• Occipital lobe- visual signals are sent
• Pariental lobe- concerned with various
information from the senses
• Temporal lobe- concerned with hearing,
memory, emotion, and speaking
• Frontal lobe- concerned with organization,
planning, and creative thinking
Lobes of the Brain
Left and Right Hemispheres
• Right and left sides of the brain
complement each other
• Left hemisphere of the brain controls the
right side of the body
– Mathematical ability, where speech is located
• Right hemisphere of the brain controls the
left side of the body
– Controls visual and spatial relations
– Perceptual tasks
How Psychologists Study the Brain
• Recording
– Electroencephalograph (EEG)- is a machine
used to record electrical activity of large
portions of the brain
– Overall electrical activity can be measured
and the rhythms of the brain differ depending
on whether a person is awake, drowsy, or
How Psychologists Study the Brain
• Stimulation
– Electrodes may be used to set off the firing of
neurons as well as record it
– Has been used with terminal cancer patients
to relieve their pain
– Used to control violent emotional behavior
• Computerized axial tomography (CT)
– An imaging technique used to study the brain
to pinpoint injuries and brain deterioration
– Radiation is absorbed depending on the
density of the brain tissue
– Computers measure the amount of radiation
absorbed and then transformed into 3-D
• Positron Emission Tomography (PET)
– Is an imaging technique used to see which
brain areas are being activated while
performing tasks
– Injects radioactive solution into the blood and
measuring the amount of radiation absorbed
by the blood cells
– Show activity in different areas of the brain
when a person is thinking, speaking, or
looking at objects
• Magnetic Resonance Imaging (MRI)
– A measuring technique used to study brain
structure and activity
– Combines the features of CT and PET scans
• fMRI- observes both the functions of
different structures of the brain and which
structures participate in specific functions
Section 3
The Endocrine System
The Endocrine System
The Endocrine Glands
• Endocrine system- a chemical
communication system, using hormones,
by which messages are sent through the
• Hormones- chemical substances that carry
messages through the body in blood
The Endocrine Glands
• Hormones have effects on your behavior
• Hormones can also influence your moods
and drives
• Duct glands
– Release their contents through small holes on
the surface of the body
• Sweat glands, tear glands, salivary glands
Pituitary Gland
• Is the center of control of the endocrine
system that secretes a large number of
• Controls growth and reproduction
including ovulation and lactation
Thyroid Gland
• Produces thyroxine
• Stimulates certain chemical reactions that
are important for all tissues of the body
• Hyperthyroidism- too much thyroxine
which causes overactivity
• Hypothyroidism- too little thyroxine makes
people feel lazy
Adrenal Glands
• Become active when angry or frightened
• Release epinephrene and norepinephrine
which cause heartbeat and breathing to
• Secrete cortical steroids which help
muscles develop
Sex Glands
• Testes
– Testosterone (male sex hormone)
• Important in physical development
• Helps decide sex of the fetus
• Ovaries
– Produce estrogen and progesterone
• Important in the development of female sex
• Vary throughout the menstrual cycle
Hormones v.s. Neurotransmitters
• Both work to affect the nervous system
• When a chemical is used as a
– It is released right beside the cell that it is to
excite or inhibit
• When a chemical is used as a hormone:
– It is released into the blood, which defuses
into the body
Section 4
Heredity and Environment
Heredity and Environment
• Heredity- the genetic transmission of
characteristics from parents to their
• Inherited factors and environmental
conditions always act together in different
Nature versus Nurture
• Nature refers to characteristics that a
person inherits
– Family, culture, education, individual
• Genes are the basic units of heredity
– Can be reproduced and passed from
generation to generation
– For example, musical talent
Twin Studies
• Identical twins- twins who come from one
fertilized egg; twins having the same
• Genes- the basic building blocks of
• Fraternal twins- twins who come from two
different eggs fertilized by two different
Twin Studies
• Twins growing up in the same house
share the same environment as well as
the same genes
• Twins growing up in different
environments have common behaviors
despite different social, cultural, or
economic backgrounds
Twin Studies
• Twin quiz
• Kasschau, Richard, A. Understanding
Psychology. McGraw-Hill, Glencoe, New
York, New York, 2008.