Biological Foundations of Behavior
3
Slide 1
Biological Foundations of Behavior
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
Biological foundations of Behavior
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
Slide 2
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
Biological foundations of Behavior
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
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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 3
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Neurons: The Units of the Nervous System
Slide 4
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Biological foundations of Behavior
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 5
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Biological foundations of Behavior
Neural Transmission
•
Neurons
–
Depolarization
– positive ions enter membrane
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All-or-none principle
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Action potential
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Myelin sheath
• Average thickness in females is greater
• May indicate females process certain information better than males
• Multiple sclerosis destroys myelin sheath
Slide 6
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Neural Transmission
Slide 7
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Biological foundations of Behavior
Neurotransmitters and Synaptic
Transmission
• Neurons work together through
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Synapse
–
Synaptic gap
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Neurotransmitters : excitatory, inhibitory
–
Synaptic vesicles
– Synaptic terminals
– Receptor sites
• Brain can be altered by use of drugs
Slide 8
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Biological foundations of Behavior
Neurotransmitters and Synaptic
Transmission
Chemicals in brain
– Acetylcholine
– Dopamine
– Serotonin
– Norepinephrine
– Glutamate
– Neuropeptides
Glial cells
– Outnumber neurons
– Produce myelin sheath
– Uses chemical
ATP
( adenosine triphosphate )
Slide 9
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Biological foundations of Behavior
Divisions of the Nervous System
•
Central Nervous System
– Brain and spinal cord
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Interneuron
•
Peripheral Nervous System
– Branches to all parts of body from CNS
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Afferent and efferent neurons
Slide 10
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Hot object
Pain receptors in skin
Slide 11
Axion of afferent neuron
Cell body of interneuron
Cell body of afferent neuron
Dendrite of afferent neuron
Axion of efferent neuron
Cell body of efferent neuron
Direction of impulse
Muscle contracts and withdraws part being stimulated
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
Biological foundations of Behavior
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 12
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Biological foundations of Behavior
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 13
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Biological foundations of Behavior
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 14
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Hindbrain and Midbrain
Midbrain
Pons
Cerebellum
Medulla
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Slide 15
Biological foundations of Behavior
Structures and Functions of the Brain
•
Reticular formation
– Spans medulla and pons
– Influence wakefulness, arousal, attention,
– Muscle control and cardiac responsiveness
Slide 16
•
Midbrain
– Center for postural reflexes linked to senses
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
Biological foundations of Behavior
Forebrain: Cognition, Motivation,
Emotion, and Action
Slide 17
•
Forebrain
– two distinct areas
– Thalamus, hypothalamus, most limbric system
•
Thalamus
– message switching station
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Hypothalamus
– motives and emotions
•
Amygdala system
– aggression, emotions
•
Hippocampus
– memories
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Forebrain
Cerebral Cortex
Thalamus
Hypothalamus
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Slide 18
Biological foundations of Behavior
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 20
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Biological foundations of Behavior
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 21
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Motor area
Voluntary movement and thinking
Broca’s area
Slide 22
Somatosensory
Body sensations
Wernicke’s area
Vision
Hearing
The Brain’s Four Lobes
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Biological foundations of Behavior
Images of the Brain at Work
• Techniques create images
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Electroencephalogram (EEG)
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Positron emission tomography (PET)
–
Magnetic resonance imaging (MRI)
•
Functional MRI measures
Slide 23
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Biological foundations of Behavior
Functions of the Hemispheres of the
Cerebral Cortex
Slide 24
Corpus Callosum
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Biological foundations of Behavior
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 25
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
Biological foundations of Behavior
• Severed corpus callosum
Split Brains
• Psychological experiments reveal processing limitations of hemispheres
– Optic chiasm not severed
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
Slide 26
Biological foundations of Behavior
Hemispheres of the Cerebral Cortex and Emotion
Slide 27
• Left hemisphere
– Processes positive emotions
– Stroke in left hemisphere – depression
• Right hemisphere
– Processes negative emotions
– Stroke in right hemisphere – no depression
•
Plasticity of cortex
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Biological foundations of Behavior
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 28
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Biological foundations of Behavior
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 29
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Biological foundations of Behavior
The Brain is an Interacting System
Slide 30
• 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
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Slide 31 Biological foundations of Behavior
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
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
Slide 32 Biological foundations of Behavior
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
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Biological foundations of Behavior
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 33
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
Biological foundations of Behavior
Glands
•
Gonads
– produce sex cells
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Ovaries and estrogen
– Testes and testosterone
•
Thyroid gland
– Regulation of metabolism
– Secretes thyroxin
– Serious deficiency: cretinism , rare type of mental retardation
Slide 34
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Biological foundations of Behavior
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
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
Slide 35
Biological foundations of Behavior
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 36
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
Biological foundations of Behavior
Genetic Influences on Behavior
• Biological mechanisms of inheritance
– Sex cells
• Gametes
•
Fertilization and zygote
– Dominant and recessive genes and traits
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Chromosome abnormalities
•
Down syndrome
– Genes influence on mental processes
Slide 37
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Biological foundations of Behavior
Research on Inheritance in Humans
•
Studies of twins
– Monzygotic : identical twins
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Dizygotic : fraternal twins
•
Studies of adopted children
– Heredity and environmental influences
Slide 38
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Biological Foundations of Behavior
The End
3
Slide 39
© 2007 The McGraw-Hill Companies, Inc. All Rights Reserved
