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Biological Foundations of Behavior

3. Biological Foundations of Behavior. 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.

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Biological Foundations of Behavior

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  1. 3 Biological Foundations of Behavior

  2. 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

  3. 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 • Dendrites: small branches extending from cell; receive messages from other neurons • Axons: small branches at other end of neuron; send messages to other neurons

  4. Neurons: The Units of the Nervous System

  5. 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

  6. Biological foundations of Behavior 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

  7. Neural Transmission

  8. Biological foundations of Behavior 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

  9. Biological foundations of Behavior 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

  10. Biological foundations of Behavior 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

  11. Axion of afferent neuron Cell body of interneuron Pain receptors in skin Cell body of afferent neuron Hot object Axion of efferent neuron Cell body of efferent neuron Dendrite of afferent neuron Direction of impulse Muscle contracts and withdraws part being stimulated

  12. 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

  13. 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

  14. 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

  15. Midbrain Pons Cerebellum Medulla Hindbrain and Midbrain

  16. 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 • Midbrain • Center for postural reflexes linked to senses

  17. Biological foundations of Behavior Forebrain: Cognition, Motivation, Emotion, and Action • Forebrain – two distinct areas • Thalamus, hypothalamus, most limbric system • Thalamus – message switching station • Hypothalamus – motives and emotions • Amygdalasystem – aggression, emotions • Hippocampus – memories

  18. Cerebral Cortex Thalamus Hypothalamus Forebrain

  19. 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

  20. 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

  21. Motor area Somatosensory Voluntary movement and thinking Body sensations Broca’s area Wernicke’s area Vision Hearing The Brain’s Four Lobes

  22. Biological foundations of Behavior Images of the Brain at Work • Techniques create images • Electroencephalogram (EEG) • Positron emission tomography (PET) • Magnetic resonance imaging (MRI) • Functional MRI measures

  23. Corpus Callosum Biological foundations of Behavior Functions of the Hemispheres of the Cerebral Cortex

  24. 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

  25. Biological foundations of Behavior Split Brains • Severed corpus callosum • Psychological experiments reveal processing limitations of hemispheres • Optic chiasm not severed

  26. Biological foundations of Behavior 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

  27. 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

  28. 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

  29. Biological foundations of Behavior 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

  30. 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

  31. 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

  32. 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

  33. Biological foundations of Behavior 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

  34. 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

  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

  36. Biological foundations of Behavior 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

  37. Biological foundations of Behavior Research on Inheritance in Humans • Studies of twins • Monzygotic: identical twins • Dizygotic: fraternal twins • Studies of adopted children • Heredity and environmental influences

  38. Biological Foundations of Behavior 3 The End

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