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Chapter 3BIOLOGY AND BEHAVIOR

Section 1: The Nervous SystemSection 2: The Brain: Our Control Center

Section 3: The Endocrine SystemSection 4: Heredity: Our Genetic Background

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Chapter 3:Section 1

The Nervous System

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Main Objective:

• Explain how messages are transmitted by neurons and describe the functions of the peripheral nervous system.

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What does the Nervous System do???

• Thinking• Feeling• Moving• Dreaming• Regulates internal functions• Learning/memory• Etc….

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Consists of 2 main parts:

1. Central Nervous System:• Brain and spinal cord

2. Peripheral Nervous System:* made up of nerve cells that send messages between the central nervous system and all the parts of the body.

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Neurons:• Neurons:– A nerve cell; the basic building block of the nervous system.– Each of us has more than 100 billion neurons!!!

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Components of a Neuron:• Cell Body: Produces energy that fuels the activity of

the cell.• Dendrites: Receive information from other neurons

and pass the message through the cell body• Axon: Carries messages away.

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Components of Neuron (cont’d)• Myelin sheath:– A white, fatty substance that insulates axons and enables rapid transmission of neural impulses.

• Axon terminals:– Small fibers branching out from an axon.

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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– A junction between the axon terminals of one

neuron and the dendrites of another neuron.– Less than a millionth of an inch wide!

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Anatomy of 2 Neurons:

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Communication (cont’d)• Messages are received by the dendrites and

travel through the cell body and the axon to the axon terminals. – They cross synapses to the dendrites of other

neurons• New synapses can develop between neurons

that were not previously connected, as when we learn something new!!

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Neurotransmitters: Chemical Messengers

• Neurons send messages across synapses through the release of neurotransmitters.– Chemicals that are stored in sacs in the axon

terminals.– 100’s can be fired every second!!

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Neurotransmitters (cont’d)• The message is converted into an electrical

impulse that travels the length of the neuron.• The message is then transmitted to the next

neuron by neurotransmitters• This whole process takes only a fraction of a

second!!!

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Different Types of Neurotransmitters!

• Acetylcholine (Ach): control of muscles.– Plays a part in Alzheimer’s disease

• Dopamine: motor behavior– Deficiency plays a role in Parkinson's disease

• Serotonin: emotional arousal and sleep

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OVERVIEW OF MESSAGE TRANSMISSION VIA NEURONS

• Messages are sent from the axon terminals of one neuron to the dendrites of other neurons

• Messages travel in one direction and are received by the dendrites and travel through the cell body and the axon to the axon terminals.

• From there messages cross synapses to the dendrites of other neurons.

Section 1: The Nervous System

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Hmmm…What do you think???Endorphins are neurotransmitters that NATURALLY

reduce pain and boost mood. Flooding the brain with painkillers, antidepressants, or other drugs may cause the brain to stop producing endorphins. Thus, when such a drug is discontinued, a person may experience a period of discomfort—ranging from mild to agonizing– until the brain resumes production of endorphins. What do you think about antidepressants? Do the benefits outweigh the potential harm?

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The Central Nervous System:Consists of brain and spinal cord

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Central Nervous System (cont’d)• Spinal cord:– A column of nerves within the spine that transmit

messages to and from the brain.– Protected by the spine.– Spinal reflex: simple, automatic response to

something.• EX: Remove hand for hot stove!

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Other simple Reflexes:

• Blink when dust in your eye• Sneeze with pepper• Tapping on knee to see if kick– Knee-jerk reflex–Want to try?…sit on desk with legs

crossed. The “doctor” needs to gently strike the knee with a “karate chop”. Does the knee jerk?

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THE PERIPHERAL NERVOUS SYSTEM

• Responsible for transmitting messages between the central nervous system and all part of the body and is made up of the somatic and autonomic nervous system

Section 1: The Nervous System

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• The somatic nervous system transmits sensory messages to the central nervous system.– Activated by touch, pain, changes in temperature,

and changes in body position.– Enables us to experience:• Hot/cold; pain/pressure; helps us maintain posture/balance.

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• The autonomic nervous system regulates the body’s vital functions such as heartbeat and breathing.

• 2 divisions:1. Sympathetic 2. Parasympathetic

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Sympathetic System:

• Activated when a person is going into action, perhaps because of some stressful event.

• “Fight-or-Flight”– Prepares you to confront situation or to run away!

• May suppress digestion, increase heart & respiration rates, and elevate blood pressure.

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Parasympathetic Nervous System:

• Restores body’s reserves of energy after an action has occurred.– EX: Heart rate and blood pressure are normalized, breathing is slowed, and digestion returns to normal.

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Chapter 3: Section 2

The Brain: Our Control Center

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Main Objective:

• Identify the major structures of the brain, and explain the functions of each structure.

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Brain Divided into 3 Sections:

1. Hindbrain 2. Midbrain3. Forebrain

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Hindbrain:• Medulla:– Vital functions such as heart rate, blood pressure, and

breathing.• Pons:– Located in front of medulla and is involved in regulating body movement, attention, sleep, and alertness.

• Cerebellum:– Balance and coordination.

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The Midbrain:

• Located between hindbrain and forebrain.• Vision and hearing• Contains part of reticular activating system:– Part of brain that is involved in attention, sleep, and

arousal.– EX: Drugs/alcohol can affect this alertness.

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The Forebrain:

Involved in complex thinking processes!!

• 4 key areas:1. Thalamus2. Hypothalamus3. Limbic System4. Cerebrum

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Thalamus:

• The structure of the brain that relays messages from the sense organs to the cerebral cortex.– EX: Relays message to brain, such as pain, in order

for brain to respond.

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Hypothalamus:• The neural structure located below the

thalamus that controls temperature, hunger, thirst, and various aspects of emotion:– Sexual behavior; caring for offspring,

aggression; etc….

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Limbic System:

• A group of neural structures at the base of the cerebral hemispheres that is associated with emotion, motivation, hunger, sex, and aggression.

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Cerebrum:

• The large mass of the forebrain, consisting of two hemispheres.

• Cerebral Cortex:– The bumpy, convoluted surface of the brain; the body’s control and information-processing center.

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The Cerebral Cortex: What Makes Us Unique

• Made up of right and left hemispheres.

• Corpus callosum:– The nerve fibers that connect the left and right hemispheres of the cerebral cortex.

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• Information received by one side of the body is transmitted to the OPPOSITE hemisphere of the brain.

• Each hemisphere of the brain is divided into four parts/lobes.

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Complete the following on the SAME handout!

• Occipital Lobe:– Vision

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Temporal Lobe:

• Hearing/Auditory

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Parietal Lobe:

• Sensory Cortex:–Warmth, cold ,touch ,and pain

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Frontal Lobe:

• Motor cortex• Neurons in the motor cortex fire when we

move certain parts of our body.

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Association Areas:

• Association areas:– Areas of the cerebral cortex that are involved in

such mental operations as thinking, memory, learning, and problem solving.

– Shape information into something meaningful.• EX: Puzzle

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Language Abilities:

Right-handed people:Language functions based in left hemisphere

About 2 out of 3 left-handed people:Language in left hemisphere

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2 Key Language Areas:• Broca’s Area:– Located in frontal lobe.– Controls area of face used for speaking.

• If damaged, then person speaks slowly, using simple sentences!

• Wernicke’s Area:– Located in temporal lobe– Pieces together sounds and sights

• If damaged, then speech becomes meaningless!!– EX: “Stealing cookies”…pg. 63

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Left vs. Right Hemispheres:

• Left Hemisphere:– Language, logic, problem solving, mathematical

computation.• Right Hemisphere:– Imagination, art, feelings, and spatial relations.

Even though have heard “right brained” and “left brained” the hemispheres DO NOT act independently of each other!!

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Midsaggital Plane:

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Turn to Pg. 65

Is Phineas Gage Still the Same Man???

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Methods of Studying the Brain:

1. Accidents:– Accidents and brain damage

2. Electrical Stimulation of the Brain:Stimulate parts of brain to change behavioral patterns.

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3. The Electroencephalogram (EEG):– Electrodes record electrical activity of brain.– Used to diagnose some psychological disorders

and locate tumors.

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4. Scans:– CAT scan : Computerized axial tomography• 3-dimensionanl view of brain.

– MRI: Magnetic resonance imaging• More powerful; shows details more clearly

– PET scan: Positron emission tomography• Show activity of brain at given time

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Chapter 3: Section 3

The Endocrine System

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Main Objective:

• Explain how hormones secreted by the major glands of the endocrine system affect the body.

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• Endocrine System:– Consists of glands that secrete substances, called

hormones, into the bloodstream.• Chemicals produced by the endocrine glands

that regulate specific body functions.• Glands include:– Pituitary gland– Thyroid gland– Adrenal glands– Testes–Ovaries

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Pituitary Gland:

• About the size of a pea.• “Master gland”…VERY IMPORTANT• Stimulated by hypothalamus:– Responsible for the secretion of many different

hormones that affect various aspects of behavior.• EX: Growth hormones; Prolactin (stimulates milk on

nursing women)

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The Thyroid Gland:• Produces Thyroxin:– Affects body’s metabolism…its rate of converting

food to energy.

– Hypothyroidism: Too little thyroxin• Can lead to overweight.

– Cretinism: Too little thyroxin in children.• Stunted growth/ mental retardation

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The Adrenal Glands:• Located above the kidneys• Outer layer (cortex):– Secrete cortical steroids, which increase

resistance to stress & promote muscle development.

– Also, cause liver to release stored sugar, making energy available for emergencies.

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Adrenal Glands (cont’d)

• Also produce adrenaline and noradrenalin:–Released when sympathetic nervous

system activated.–Help arouse body, enabling person to cope with stressful situation.

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The Testes and the Ovaries:

• Testes and Ovaries – produce the hormones testosterone, estrogen, and progesterone that play an important role in development, development of primary and secondary sex characteristics and have psychological as well as biological effects.

Section 3: The Endocrine System

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Testosterone:• Male sex hormone.– Small amount in females produced by ovaries.

• Produced by testes in males.• Stimulates growth of male sex organs.

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Estrogen and Progesterone:• Female sex hormones produced by ovaries.– Low levels found in men.

• Responsible for the following:– Breast enlargement; regulates menstrual cycle;

PMS; higher levels of estrogen connected with feelings.

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Chapter 3: Section 4

Heredity: Our Genetic Background

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Main Objective:

• Explain the role of chromosomes and genes in heredity and evaluate the methods used by psychologists to study the role of heredity in determining traits.

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What is Heredity??

• Heredity:– The transmission of characteristics from parents to

offspring.

– Contribute to the following:• Appearance, personality, psychological disorders

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Genes and Chromosomes:• Genes:– The basic building blocks of heredity.– Traits determined by pairs of genes…one gene in each pair

from each parent.• Chromosomes:– Threadlike structures in which genes are found, which are

composed of DNA (deoxyribonucleic acid)– Double helix– 46 chromosomes with 23 pairs

• In pairs…one from mom and one from dad.

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Oh!!! It’s A ?????• 23rd pair:– Determines sex

• Female:– 2 X-chromosomes

• Male:– 1 X & 1 Y chromosome– Father determines sex of baby!

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Nature vs. Nurture:• Nature:– What people inherit.

• Nurture:– Environmental factors• Family, education, culture, everyday living experiences

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What do most psychologists believe??

Believe nature & nurture are equally important!

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Kinship Studies:• Kinship:– Refers to the degree to which people are related,

based on genes.

– 2 Common types:1. Twin Studies2. Adoptee Studies

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Twin Studies:• Identical twins:– Differences due to environment (nurture)– More likely to share personality traits &

psychological disorders (Ex: autism)

• Fraternal twins:– Differences due to genes AND environment• Share 50% of genes

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Adoptee Studies:• If children act more like biological families –

then behavior may be largely influenced by heredity!!

• Provides ways of sorting out the effects of nature and nurture

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Twins Reared Apart:• Psychological and personality traits are influenced by

heredity.• A way of finding out that twins reared apart share many of the same mannerisms despite their separation

– EX: Intelligence, aggression, leadership.– http://www.youtube.com/watch?v=Vlr4mwtjEKY

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Does Heredity Determine Our Personalities??

Turn to Pg. 73

End of Chapter 3