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© 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 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
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
Slide 4
Neurons: The Units of the Nervous System
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
Slide 7
Neural Transmission
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
Slide 9
Neurotransmitters and Synaptic Transmission
Glial cells– Outnumber neurons
– Produce myelin sheath
– Uses chemical ATP
(adenosine triphosphate)
Biological foundations of Behavior
Chemicals in brain– Acetylcholine
– Dopamine
– Serotonin
– Norepinephrine
– Glutamate
– Neuropeptides
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
Slide 15Hindbrain and Midbrain
MedullaMedulla
Pons
Cerebellum
Midbrain
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
Slide 18
Forebrain
ThalamusThalamus
Hypothalamus
Cerebral Cortex
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
Slide 22
Wernicke’s area
Broca’s area
Motor area SomatosensoryVoluntary
movement and thinking Body sensations
Vision
Hearing
The Brain’s Four Lobes
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
Slide 23
Images of the Brain at Work
• Techniques create images– Electroencephalogram (EEG)
– Positron emission tomography (PET)
– Magnetic resonance imaging (MRI)
• Functional MRI measures
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
Slide 24
Functions of the Hemispheres of the Cerebral Cortex
Biological foundations of Behavior
Corpus CallosumCorpus Callosum
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
Slide 26
Split Brains
• Severed corpus callosum
• Psychological experiments reveal processing limitations of hemispheres
– Optic chiasm not severed
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
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
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
Slide 38
Research on Inheritance in Humans
• Studies of twins– Monzygotic: identical twins
– Dizygotic: fraternal twins
• Studies of adopted children– Heredity and environmental influences
Biological foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
Slide 39
The End
3Biological Foundations of Behavior
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