Chapter 6: Body and Behavior
Section 1 – The Nervous System: The Basic Structure
A. How the nervous system works
a. It is never at rest
b. Controls our emotions, movements, thinking and behavior
c. It is divided into 2 parts (Figure 6.1)
i. Central Nervous System (CNS)
1. Consists of the brain and spinal cord
ii. Peripheral Nervous System (PNS)
1. Smaller Branches of nerves that reach other parts of the
body from the spinal cord (thickness of a pencil)
2. Take information from the organs to the CNS and from the
CNS back to the organs
d. Each is protected by something
i. Brain by the skull and several layers of sheathing
ii. Spinal cord by the vertebrae
iii. Peripheral nerves by layers of sheathing
e. Neurons (Figure 6.2)
i. Nerves are long, thin cells called neurons
1. Messages travel along these
2. Neurons can fire (or transmit signals) hundreds of times a
minute
ii. Neurons have three basic parts
1. The cell body
a. Contains the nucleus and produces the energy
needed to fuel neuron activity
2. Dendrites
a. Short, thin fibers that stick out from the cell body
and receive impulses from other neurons and send
them to the cell body
3. Axons
a. Long fiber that carries the impulses away from the
cell body toward the dendrites of the next neuron
4. Other structures
a. Myelin Sheath – white, fatty substance insulates
and protects the axon
i. If it is destroyed, behavior of the person can
be erratic and uncoordinated (as in MS)
ii. Speeds the transmission of impulses
b. Axon terminals – branch out from the end of the
axon, they are positioned directly opposite of the
dendrite.
iii. Neuron connection (Figure 6.3)
1. Synapse – the space between the axon terminals of one
neuron and the dendrites of another neuron.
a. This is the junction or connection between neurons
b. Neurons transmit impulses or messages across this
space using neurotransmitters
i. Neurotransmitters – are chemicals that
either excite the next neuron or stop it from
transmitting
ii. There are different types of
neurotransmitters
1. Norepinephrine – involved in
memory or learning
2. Endorphin – inhibits pain
3. Acetylocholine – involved in
movement and memory (associated
with paralysis and Alzheimer’s)
4. Dopamine – involved in learning,
emotional arousal and movement
(too much is associated with
schizophrenia and too little with
Parkinson’s)
5. Serotonin (an undersupply linked
with a lack of norepinephrine is
associated with depression)
f. Voluntary and Involuntary Activities
1. Somatic Nervous System (SNS) – refers to the part of the
peripheral nervous system that controls voluntary activities
a. Body making a response to impulses from the
nerves like turning a page in a book
2. Autonomic Nervous System (ANS) – refers to the part of
nervous system that controls involuntary activities, or those
that occur automatically
a. Your heartbeat, breathing, stomach activity
b. Has two parts
i. Sympathetic nervous system – prepares the
body for dealing with emergencies or
strenuous activities
1. Speeds up the heart to hasten the
supply of blood and nutrients to body
tissues
ii. Parasympathetic nervous system – works to
conserve energy and to enhance the body’s
ability to recover from strenuous activity
1. Reduces heart rate and blood
pressure to bring the body back to its
resting state
Section 2 – Studying the Brain
A. The brain is composed of three parts
a. The Hindbrain
i. Located at the rear base of the skull
ii. Involved in the most basic processes of life
iii. Includes:
1. The cerebellum
2. The medulla
3. The pons
b. The Midbrain
i. Integrates sensory information
ii. Alerts the rest of the brain to incoming signals and is involved in
the sleep/wake cycle
c. The Forebrain
i. All information from the senses, minus smell, come through the
thalamus
ii. Controls: hunger, thirst, sexual behavior, reaction to temperature
iii. Higher level thinking processes
1. Ability to learn and store complex and abstract information;
project thinking into the future
2. See, read and understand
3. Regulates emotions and motivations
iv. Includes:
1. Thalamus
2. Cerebral Cortex
3. Cerebrum
4. Limbric System
a. Hypothalamus, amygdala (violent emotions and
fear), thalamus and hippocampus (memory)
B. Lobes of the brain
a. Cerebrum is split into 2 sides or hemispheres
i. Connected by the corpus callosum
b. Occipital Lobe
i. Where visual signals are processed
ii. Damage may cause visual impairment
c. Parietal Lobe
i. Receives and deals with information from all the senses
d. Temporal Lobe
i. Concerns: hearing, memory, emotion and thinking
e. Frontal Lobe
i. Concerned with organization, planning and creative thinking
f. Somatosensory Cortex
i. Receives information from the touch sensors
g. Motor Cortex
i. Sends information to control body movement
h. All these areas work together
C. The Hemispheres
a. Each work together to compliment and help each other
b. Corpus callosum carries information back and forth between the
hemispheres and the lobes (each of the 4 lobes are present in both
hemispheres)
c. Left Hemisphere
i. Controls movement on the right side of the body
ii. Where speech is located (in most people)
iii. Specialized for mathematical ability, calculation and logic
d. Right Hemisphere
i. Controls the left side of the body
ii. Adept at visual and spatial relations
iii. Perceptual tasks
iv. Recognizing patterns (music and art)
v. Creativity and intuition
D. Split Brain Operations
a. Usually done to those with severe seizures
b. Cuts the corpus callosum
i. Lowers the severity and number of seizures
ii. Information cannot cross into other spheres
1. Person with a split brain can hold a ball in their right hand
and say it was a ball, but not holding it in their left hand
c. Shows how unique and the specialize functions and skills of each
hemisphere
d. Remained practically unchanged in intelligence, emotion and personality
E. How Psychologists study the brain
a. Recording
i. Putting electrodes into the brain to record electrical activity
ii. EEG – electroencephalograph. Millions and millions of neurons
can be studied at one time with an EEG attached to the scalp
iii. Shows brain waves which show the amount of neural activity
b. Stimulation
i. Fires off neurons by electricity
ii. Can show what areas of the brain do
1. Memories
2. Songs
3. Smells
c. Lesions
i. Cutting or destroying areas of healthy brain tissue and studying the
results
d. Accidents
i. Studying the results of accidents and medical issues
1. Phineas Gage
2. Coma patients
3. Traumatic head injuries
e. Images
i. CAT (Computerized Axial Tomography) scans
1. Transfers the amount of radiation absorbed by the density
of brain tissue into a 3 dimensional view of the brain
ii. PET (Positron Emission Tomography) scans
1. Shows the absence or presence state of activity in an area
of the brain through radioactive dye
iii. MRI (Magnetic Resonance Imaging)
1. Ability to study both activity and brain structure
2. Uses both CAT and PET scanning capabilities
iv. fMRI (Functional Magnetic Resonance Imaging)
1. New, can see the blow flow into active areas to determine
activity and functionality
Section 3 – The Endocrine System
A. Endocrine system – sends chemical messages to and from the brain
a. Chemical messages used to send are called hormones
i. Produced by the glands and send by blood and other bodily fluids
ii. Once in the blood stream, they can only be received by the specific
organs that they can influence
iii. Ductless, they don’t need pores or ducts (small holes) to release to
an organ (sweat glands, tear glands, salivary glands)
iv. Various effects on behavior and moods
v. Growth of organs, muscles and bones
b. Pituitary Gland
i. Directed by the hypothalamus
ii. Secretes a large number of hormones, many of which control the
output of other hormones
1. Corrects imbalances of hormones in the body
2. Keeps metabolism in check despite outside influences
3. Control growth and reproduction
c. Thyroid Gland
i. Produces thyroxine
1. Stimulates chemical reactions for all tissues
2. Too little, people feel lazy; too much people lose weight,
sleep too much and are overactive
d. Adrenal Gland
i. Become active when someone is angry or frightened
ii. Release Epinephrine (adrenaline) and norepinephrine (nor
adrenaline)
iii. Speed up heart rate and breathing; heighten emotion; extra energy
iv. Secret cortical steroids
1. Help muscle develop and cause the liver to release stored
sugar for extra energy in emergencies
e. Sex Glands
i. 2 Types
1. Testes – male
a. Produce sperm and testosterone (sex hormone)
2. Ovaries – females
a. Produce eggs and estrogen and progesterone
ii. Testosterone
1. Important to physical development of males during the
prenatal and adolescence periods
a. Prenatal – helps decide the sex of the fetus
b. Adolescence – development of bone and muscle,
male sex characteristics
iii. Estrogen and progesterone
1. Development of the female sex characteristics
2. Regulate the reproductive cycle
3. Variances of the hormones cause the symptoms of PMS
B. Hormones vs. Neurotransmitters
a. Difference
i. When the chemical is released right beside a cell to excite or
inhibit it, it is a neurotransmitter
ii. When a chemical is released into the blood, it is a hormone
Section 4 – Heredity and Environment
A. Is human behavior instinctive (due to heredity) or learned (environment)
a. Heredity is the genetic transmission of characteristics from parents to
their offspring
b. Are people born a certain way or did they learn it?
B. Nature vs. Nurture
a. Genes and behavior
i. Reproduced and passed onto children
ii. Occur through their role in building and modifying the physical
structures of the body
b. Twin studies
i. Identical twins – develop from the same single, fertilized egg,
thus sharing the same genes
ii. Fraternal twins – develop from 2 fertilized eggs, not more similar
genes than brothers or sisters
iii. One study showed that twins growing up apart from one another
showed similar behaviors, despite different socials, cultural and
economic backgrounds
1. Suggests heredity may contribute to behaviors once thought
more environment in nature
2. It is possible though to alter the environment that genes
operate in thus changes these “hereditary” ideas