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