Psychology Chapter 3

What does our nervous system do for us?

  • It is involved in thinking, learning, memory, dreaming, feeling, moving, and much more.
  • It is working when we are active, still, awake, and asleep.
  • It is involved in how we interact with the world.

 What are the two main parts of the nervous system?

Central Nervous System:  The brain and spinal cord

Peripheral Nervous System:  Nerve cells that send messages between the central nervous system and all the parts of the body.

In order to understand how the central and peripheral nervous systems work, we must first understand how nerve cells communicate with one another and how their messages travel through the body.

Neurons:  Nerve Cells

  • Neurons can communicate with one another and often send messages from other parts of the body such as muscles and glands.
  • We have more than 100 billion neurons, most of which are found in the brain.

Parts of a neuron.

Cell Body: Produces energy that fuels the activity of the cell.

Dendrites:  Receive information from other neurons and pass INTO the cell.

Most neurons have many dendrites, but only one axon.

Axon:  Carries messages AWAY from the cell.

Myelin:  A white fatty substance that insulates and protects the axon.  It also helps to speed up the transition of messages.

Axon Terminals: Small fibers branching out from an axon.

The communication Process

  • Messages are sent from the axon terminals of one neuron to the dendrites of other neurons.  In order for a message to be sent from one neuron to another neuron, it must cross the synapse.
  • Synapse:  the space between the axon terminals of the sending neuron and the dendrites of the receiving neuron.
  • Messages may only travel in ONE direction.
    • Message received by dendrites à Travel through the cell body à Travel through the axon à Travel to axon terminals à Cross synapses to the dendrites of other neurons. 
    • New synapses can develop between neurons when we learn something new.
  • Sensory neurons carry information received by the senses to the central nervous system.
  • Motor neurons carry information from the central nervous system to the muscles and the glands and influence their functioning.

Notes Break:  Sensory Chain “Telephone”

  • Students should stand close together and create a chain.
  • Tell students to imagine that they are sensory neurons and that the last person in the chain is the brain.
  • Devise a code system by which a certain number of hand squeezes represents a certain sensation such as cold or pain.
    • Example:  2 Squeezes – Cold / 1 Squeeze – Pain / etc.
  • Explain that by squeezing the hand of the person next to them, the students are simulating the transmission of neural impulses.

Neurotransmitters:  Chemical Messengers

  • Neurons send messages across synapses through the release of neurotransmitters;
    • Neurotransmitters:  A chemical messenger that carries impulses across the synaptic gaps between neurons.
  • Neurons send their messages by releasing neurotransmitters like water shooting out of spray bottle.
  • There are many types of neurotransmitters, but each has its own structure and fits into only a certain type of receptor.  Much like a key fits into a lock.
    • The process:  Neurotransmitter fits into receptor à Message is converted into an electrical impulse that travels the length of the neuron à This message is then transmitted to the next neuron by neurotransmitters à Repeat
      • This process continues until the message arrives at its destination. 
      • This usually takes only a fraction of a second
  • Neurotransmitters are involved in everything we do.
  • Some diseases and psychological disorders may be caused by the presence of too much or too little of various neurotransmitters.
  • Examples of neurotransmitters:
    • Acetylcholine:  Involved in the control of muscles.
    • Dopamine: Involved with motor behavior.
    • Noradrenaline:  Prepares the body for action
    • Serotonin: Involved in emotional arousal and sleep.

The Central Nervous System

  • Consists of the neurons of the spinal cord and the brain.
  • Spinal Cord:  A column of nerves within the spine that transmit messages to and from the brain.
    • Involved in spinal reflexes: an automatic response to something.

The Peripheral Nervous System

  • Responsible for transmitting messages between the central nervous system and the rest of the body.
  • It is broken into two main parts:
    • Somatic Nervous System: transports messages to the central nervous system
      • Activated by touch, pain, changes in temperature, changes in body position (to help us maintain balance)
      • Responsible for letting us feel hot, cold, pain, and pressure.
    • Automatic Nervous System: regulates the body’s vital functions such as heartbeat, breathing, digestion, and blood pressure.
      • Automatic means “occurring involuntary” or automatically
      • Psychologists are interested in your automatic nervous system because of its involvement in the experience of emotion.
      • The response of the automatic nervous system is important when a person experiences something stressful in the environment.
      • The automatic nervous system has two parts:
        • Sympathetic nervous system
          • Activated when a person goes into action, usually due to a stressful event.
          • Prepares the body to either confront the situation or run away.
            • This is called the fight-or-flight response.
          • It prepares the body by suppressing digestion, increasing the heart and respiration rates, and elevating the blood pressure.
          • Sympathetic responds to Stress
        • Parasympathetic nervous system
          • Restores the body’s reserve energy after action has occurred.
          • Heart rate and blood pressure are returned to normal, breathing is slowed, and digestion turns back to normal.
          • Parasympathetic returns to Peace



The Brain:  Our Control Center                   My Brain Study Guide

Parts of the brain:  The human brain is made of many parts that work together to organize our movements, create our thoughts, form our emotions, and produce our behaviors. Scientists have identified the localized functions of different parts of the brain.

  • Hindbrain:  the lower portion of the brain involved in many vital functions like heart rate, respiration, and balance.
    • Important parts:
      • Medulla:  involved in vital functions like heart rate, blood pressure, and breathing.
      • Pons:  located in front of the medulla and is involved in regulating body movement, attention, sleep, and alertness.
      • Cerebellum:  Latin for “little brain,” it looks like the larger part of the brain (the cerebrum), under which it rests, but is much smaller.  It is involved in balance and coordination.
  • Midbrain:  includes the areas that are involved in vision and hearing.
    • Important parts:
      • Reticular activating system:  important for attention, sleep, and arousal. 
        • When it is stimulated, we are more alert.
        • It affects arousal by increasing heart rate, blood pressure, and brain activity.
  • Forebrain:  the front area of the brain involved in complex functions such as thought and emotion.
    • Important parts:
      • Thalamus:  acts as a relay station for sensory stimulation.  It relays information from sense organs to the cerebral cortex.
      • Hypothalamus:  located under the thalamus (Hypo is the Greek word for under).  It is tiny, but very important.    It is involved in any aspects of behavior and physiological functions  it is vital to the regulation of body temperature, the storage of nutrients, and various aspects of motivation and emotion.  It is also involved hunger, thirst, caring for offspring, and aggression. 
      • Limbic System:  forms a fringe along the inner edge of the cerebrum.  It is involved in learning, memory, emotion, hunger, sex, and aggression.
      • Cerebrum:  Latin for “brain” is the crowning glory of the brain.  It is made of two hemispheres. Humans are the only animals in which the cerebrum takes up a large portion of the brain (70%).  The surface is the wrinkled, and is referred to as the cerebral cortex.

The Cerebral Cortex:  What makes us unique?

  • What is it?
    • Cerebral Cortex: 
      • The bumpy, convoluted surface of the brain.
      •  It is the part we tend to think of when we hear the word “brain.”
      •  It is the body’s control and information processing center.
      •  It makes us uniquely human as it is the part that thinks.
      •  It also deals with:  memory, language, emotions, complex motor functions, perception, and much more. 
      • It is made of two sides called hemispheres.
    • Corpus Callosum:  the nerve fibers that connect the left and right hemispheres of the cerebral cortex.  It aides in getting information from one side of the brain to the other.
  • Some Facts:
    • Information received by one side of the body is transmitted to the opposite hemisphere of the brain.
      • Ex.  If you touch something with your left hand, that information is sent to the right side of your brain.
    • The cerebral cortex is divided into four parts called lobes:
      • Frontal
      • Temporal
      • Occipital
      • Parietal
  • Senses and motor behavior
    • The occipital lobe contains the primary visual area of the cerebral cortex
    • The temporal lobe contains the hearing, or auditory, area.
      • Sounds are relayed from the ears to the thalamus and from the thalamus to the auditory area.
    • The parietal lobe is responsible for the sense of touch.
      • It includes warmth, cold, touch, and pain.
  • Association areas:  areas of the cerebral cortex that are involved in such metal operations as thinking, memory, learning, and problem solving.  They shape information into something meaningful.
    • The associations areas in the frontal lobes, near the forehead, could be called the brain’s executive center where we solve problems and make plans and decisions.
    • Association areas provide our core working memory.
  • Language Abilities
    • There are two key language area of the brain:
      • Broca’s area:
        • Located in the frontal lobe near the section of the motor cortex that controls the areas of face used for speaking.
      • Wernickes’s area
        • Located in the temporal lobe, pieces together sounds and sights
  • Left versus right hemispheres
    • Right hemisphere:
      • Relatively more concerned with the imagination, art, feelings, and spatial relations
    • Left hemisphere:
      • Contains most language functions and is usually more involved in logic, problem solving, and mathematical computation.
    • Note:  Although some differences do exist between the two hemispheres, the hemispheres do not act independently of each other.

Methods of studying the brain:  much of our earlier understanding of the brain came from studies of people with head injuries.  Today, researchers increase their knowledge of the brain and its functions by using a variety of techniques to study damaged and intact brains.  Using these techniques, psychologists have learned that the mind is the product of the brain. 

  • Accidents
    • Psychologists studies those who have been in accidents.
    • They may look at brain damage which can result in loss of vision, hearing, confusion, or loss of memory.
    • Sometimes the loss of large portions of the brain may result in little use of function yet loss of smaller, but more vital, parts could result in language problems, memory loss, or even death.
  • Electrical Stimulation of the brain
    • This has shown that specific area of the brain are associated with different sensations.
    • This is not always a reliable tool because stimulation at the same place can produce different effects at different times.
      • Example:  the areas that produce pleasant and unpleasant sensation in people may also vary from person to person and day to day.
  • The electroencephalogram (EEG)
    • This is a device that records the electrical activity of the brain.
    • Psychologist study brainwaves with this machine, and may use it to diagnose psychological disorders and locate tumors.
  • Scans
    • These often produce computer generated images of the brain which can provide information about bran damage and abnormalities
    • The most common scans used are the computer axial tomography (CAT),  magnetic resonance imaging (MRI), and positron emissional tomography (PET)

Notes Chapter 3 Section 3:  The Endocrine System

Endocrine system:  The glands that secrete hormones into the bloodstream.

Hormones:  Chemicals produced by the endocrine glands that regulate specific body functions.

  • The word hormone is derived the from the Green “horman” meaning “to stimulate” or “to excite”.
  • Hormones stimulate growth and many kinds of reactions, such as changes in activity levels and moods.
  • Hormones are produced by several different glands including the pituitary, thyroid, adrenal, testes, and ovaries. (Diagram)
  • Why are psychologists interested in the endocrine system?
    • Because hormones affect behavior and emotional reactions.
  • The Pituitary Gland – The MASTER GLAND
    • It is located below the hypothalamus and is about the size of a pea.
    • Responsible for the secretion of many different hormones that affect various aspects of behavior.
      • Examples:
        • Growth hormone:  regulates growth of muscles, bones, and glands.
        • Oxytocin:  stimulates labor in pregnant women.
  • The Thyroid Gland – Affects the body’s metabolism (its rate of converting food to energy.)
    • It produces thyroxin.
    • Production of too little thyroxin in adults can lead to hypothyroidism causing someone to be overweight.
    • Production of too little thyroxin in children can lead to cretinism which is characterized by stunted growth and cognitive issues.
    • People who produce too much thyroxin may have hyperthyroidism causing excitability, inability to sleep, and weight loss.
  • The Adrenal Glands – cortical steroids, adrenaline, noradrenaline
    • Located above the kidneys.
    • Secrete:
      • Cortical steroids – increase resistance to stress and promote muscle development.
      • Adrenaline/Noradrenaline – during a stressful situation the sympathetic nervous system causes the adrenal glands to release a mixture of these two hormones which help arouse the body and allow the person to cope with the stressful situation.
        • Adrenaline also plays a role in the emotions people experience:
          • It can intensify emotions like fear and anxiety.
  • The Testes and Ovaries – produce testosterone, estrogen and progesterone – all play an important part in development.
    • Testosterone - Found in both males and females (only a small amount in females)
    • Estrogen and Progesterone - Found in females and males (only a small amount in males)
      • Changes in the level of estrogen in females can lead to premenstrual syndrome (PMS).


Chapter 3 Notes Section 4:  Heredity: Our Genetic Background

Heredity:  the passing down of characteristics from parents to offspring.

Why do psychologists study heredity?

  • It is one way of looking at why people behave the way they do.
  • Heredity plays a role in the development of traits (in humans and animals)
  • The traits we inherit shape behavior.

Things we get through heredity:

  • Height
  • Hair texture
  • Eye color
  • Some psychological traits like shyness, leadership ability, and aggressiveness may all be influenced by heredity.

*Keep in mind that the environment also plays a role in shaping these traits

-  Psychological disorders that have links to heredity include: anxiety, schizophrenia, bipolar disorder, and alcoholism.

Genes:  the basic building blocks of heredity.

Chromosomes: a microscopic threadlike structure in the nucleus of every living cell; it contains genes and is composed of DNA.

  • Most humans have 26 chromosomes organized into 23 pairs each (one from mom and one from dad)
  • Each chromosome contains instructions for the development of particular traits in the individual.
  • 22 of the 23 pairs of chromosomes are similar in males and females.
    • The 23rd pair, the sex chromosomes, determines whether we are female or male.
      • Males:  Have an X and a Y chromosome
      • Females:  Have two X chromosomes.
  • Which hormone determines the sex of the baby?
    • The  Dad’s – He can contribute either an X chromosome making the baby female or a Y chromosome making the baby male.
  • When a child is born without 46 chromosomes in each cell, physical and behavioral disorders might result.
    • The most common is when there is a third chromosome on the 21st pair – Down Syndrome