© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide 1 Biological Foundations of Behavior 3

© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved

Slide 1

Biological Foundations of Behavior

3


Slide 2

Nervous System: Biological Control Center

• Brain – thinks, calculates, feels, and controls motivation

• Spinal cord – Bundle of long nerves running through spine– Connects brain to every part of body

Biological foundations of Behavior


Slide 3

Neurons: The Units of the Nervous System

• Neuron – individual nerve cell

• Parts of neurons– Cell body: central part of nerve cell; contains

nucleus or cell’s control center

– Dendrites: small branches extending from cell; receive messages from other neurons

– Axons: small branches at other end of neuron; send messages to other neurons



Slide 4

Neurons: The Units of the Nervous System


Slide 5

Neural Transmission

• Neurons – Function like wires and batteries– Have sacs filled with fluid chemicals containing

surrounded by a second type of chemical– Ions: positive or negative changed particles– Cell membrane

• semipermeable in normal resting state

– Polarized when negative ions inside cell membrane and positive ions outside



Slide 6

Neural Transmission

• Neurons– Depolarization – positive ions enter membrane– All-or-none principle – Action potential– Myelin sheath

• Average thickness in females is greater

• May indicate females process certain information better than males

• Multiple sclerosis destroys myelin sheath



Slide 7

Neural Transmission


Slide 8

Neurotransmitters and Synaptic Transmission

• Neurons work together through– Synapse

– Synaptic gap

– Neurotransmitters: excitatory, inhibitory

– Synaptic vesicles

– Synaptic terminals

– Receptor sites

• Brain can be altered by use of drugs



Slide 9

Neurotransmitters and Synaptic Transmission

Glial cells– Outnumber neurons

– Produce myelin sheath

– Uses chemical ATP

(adenosine triphosphate)


Chemicals in brain– Acetylcholine

– Dopamine

– Serotonin

– Norepinephrine

– Glutamate

– Neuropeptides


Slide 10

Divisions of the Nervous System

• Central Nervous System– Brain and spinal cord– Interneuron

• Peripheral Nervous System– Branches to all parts of body from CNS– Afferent and efferent neurons



Slide 11

Direction of impulse

Muscle contracts and withdraws part being

stimulated

Axion of efferent neuron

Pain receptors in skinAxion of

afferent neuronCell body of interneuron

Cell body of afferent neuron

Dendrite of afferent

neuron

Cell body of efferent neuron

Hot object


Slide 12

Divisions of Peripheral Nervous System

• Somatic nervous system– Voluntary movements and skeletal muscles– Receives and send messages

• Autonomic nervous system– Carries messages to organs, has 2 functions

• Essential body functions• Emotion



Slide 13

Divisions of Autonomic Nervous System

• Sympathetic nervous system– Responds to psychological or physical stress– Activates and inhibits organs

• Parasympathetic nervous system– Helps maintain balanced regulation of internal

organs and large body muscles– Stimulates maintenance activities and energy

conservation



Slide 14

Structures and Functions of the Brain

• Hindbrain– Routine functions that keep body working

– Three main parts

• Medulla – breathing and reflexes

• Pons – balance, hearing

• Cerebellum – coordinates complex muscle movements



Slide 15Hindbrain and Midbrain

MedullaMedulla

Pons

Cerebellum

Midbrain


Slide 16

Structures and Functions of the Brain

• Reticular formation– Spans medulla and pons

– Influence wakefulness, arousal, attention,

– Muscle control and cardiac responsiveness

• Midbrain – Center for postural reflexes linked to senses



Slide 17

Forebrain: Cognition, Motivation, Emotion, and Action

• Forebrain – two distinct areas

– Thalamus, hypothalamus, most limbric system

• Thalamus – message switching station

• Hypothalamus – motives and emotions

• Amygdala system – aggression, emotions

• Hippocampus – memories



Slide 18

Forebrain

ThalamusThalamus

Hypothalamus

Cerebral Cortex


Slide 20

Forebrain: Cognition, Motivation, Emotion, and Action

• Forebrain – two distinct areas

– Primarily cerebral cortex

• Sensory, cognitive, and motor functions

• Conscious experiences

• Voluntary actions

• Language and intelligence



Slide 21

Lobes of the Cerebral Cortex

• Lobes – four sections of brain– Frontal lobes – thinking, memory, decisions

• Broca’s area – ability to speak

• Phineas Gage

– Association areas – general roles in cerebral

activities



Slide 22

Wernicke’s area

Broca’s area

Motor area SomatosensoryVoluntary

movement and thinking Body sensations

Vision

Hearing

The Brain’s Four Lobes


Slide 23

Images of the Brain at Work

• Techniques create images– Electroencephalogram (EEG)

– Positron emission tomography (PET)

– Magnetic resonance imaging (MRI)

• Functional MRI measures



Slide 24

Functions of the Hemispheres of the Cerebral Cortex


Corpus CallosumCorpus Callosum


Slide 25

Functions of the Left and Right Cerebral Hemispheres

• Left cerebral hemisphere– Language control in 90% of population– Analyzes logical verbal information

• Right cerebral hemisphere– Processes shapes and location of things– Visual and spatial information

• Corpus callosum



Slide 26

Split Brains

• Severed corpus callosum

• Psychological experiments reveal processing limitations of hemispheres

– Optic chiasm not severed



Slide 27

Hemispheres of the Cerebral Cortex and Emotion

• Left hemisphere– Processes positive emotions– Stroke in left hemisphere – depression

• Right hemisphere– Processes negative emotions– Stroke in right hemisphere – no depression

• Plasticity of cortex



Slide 28

Human Diversity: Sex Differences in the Cerebral Cortex

• Female brain – average size smaller than that of male brain– More folds and complex

– Greater surface area

– More accurate in verbal task performance

– More activation in left cerebral hemisphere

• Male brain – More activation in right cerebral hemisphere



Slide 29

The Brain is a Developing System

• Brain structure changes over lifetime

• Total brain weight same after age 5

– Gray matter decreases as white matter increases in cerebral cortex

– White matter: continued myelin growth but decreases after fifth decade of life

– Gray matter decrease: neural pruning

– Neurogenesis: controversial issue



Slide 30

The Brain is an Interacting System

• Cerebral cortex – evaluates threats

• Limbic system – process emotional arousal

• Motor areas of cortex work with hindbrain and midbrain to coordinate muscular movements

• Parallel rather than serial processing



Slide 31

Endocrine System: Chemical Messengers of the Body

• Endocrine system – regulation of bodily processes

– Glands – secrete neuropeptides and hormones

– Hormones

• Directly regulated by brain

• Chemically identical to some neurotransmitters

• Activate body organs during physical stress or emotional arousal



Slide 32

Glands

• Pituitary Gland– Largely controlled by hypothalamus– Regulates body’s reaction to stress and resistance

to disease

• Adrenal glands– Pair of glands atop kidney– Secrete variety of hormones in emotional arousal

• Epinephrine and norepinephrine• Cortisol



Slide 33

Islets of Langerhans

• Embedded in pancreas – regulate sugar in blood

• Glucagon – causes liver to put sugar in blood stream

• Insulin – reduces sugar level in blood



Slide 34

Glands

• Gonads – produce sex cells– Ovaries and estrogen– Testes and testosterone

• Thyroid gland– Regulation of metabolism– Secretes thyroxin– Serious deficiency: cretinism, rare

type of mental retardation



Slide 35

Glands

• Parathyroid glands– Four small glands in thyroid– Secrete parathormone– Regulates ion levels in neurons

• Too much – lethargy• Too little – excessive nervous activity

• Pineal gland– Attached to top of thalamus– Secretes melatonin – regulates moods



Slide 36

Genetic Influences on Behavior

• What is inherited?– Physical traits

– Specific behavioral patterns

• Biological mechanisms of inheritance– Genetic codes

• Mendel – science of genetics

• Genes, chromosomes, and DNA



Slide 37

Genetic Influences on Behavior

• Biological mechanisms of inheritance– Sex cells

• Gametes

• Fertilization and zygote

– Dominant and recessive genes and traits

– Chromosome abnormalities

• Down syndrome

– Genes influence on mental processes



Slide 38

Research on Inheritance in Humans

• Studies of twins– Monzygotic: identical twins

– Dizygotic: fraternal twins

• Studies of adopted children– Heredity and environmental influences



Slide 39

The End

3Biological Foundations of Behavior

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© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved Slide 1 Biological Foundations of Behavior 3