PSYCH 101 Chapter 3
PSYCH 101 Chapter 3 PSYC 101 003
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This 8 page Class Notes was uploaded by Marika O'Hara on Saturday September 10, 2016. The Class Notes belongs to PSYC 101 003 at University of North Carolina - Chapel Hill taught by Frederick Wiss in Fall 2016. Since its upload, it has received 4 views. For similar materials see Introduction to Psychology in Psychology (PSYC) at University of North Carolina - Chapel Hill.
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Date Created: 09/10/16
Chapter 3 Friday, September 9, 201610:25 AM The Biological Bases of Behavior Communication in the Nervous System • Behavior depends on rapid information processing Nervous Tissue: The Basic Hardware Neurons • Neurons: individual cells in the nervous system that receive, integrate, and transmit information ○ Basic links that can communicate with the nervous system • Soma: cell body that contains the cell nucleus and much of chemical machinery common to most cells • Dendrites : parts of a neuron that are specialized to receive information ○ Neurons have dendrite trees with branches • Information flows from the dendrites, into the cell body, and then away from the soma along the axon • Axon: a long, thin, fiber that transmits signals away from the soma to other neurons or to muscles or glands • Axons are wrapped in cells with lots of myelin • Myelin sheath: insulating material that encases some axons • Axon ends in a cluster of terminal buttons ○ Terminal buttons : small knobs that secrete chemicals called neurotransmitters • Synapse: a junction where information is transmitted from one neuron to another Glia • Glia: cells found throughout the nervous system that provide various types of support for neurons ○ Glia are smaller than neurons but there are ten times as many ○ Glia cells account for half of the brain's volume • Glia cells supply nourishment to neurons, help remove neurons' waste products and provide insulation around many axons The Neural Impulse: Using Energy to Send Information The Neuron at Rest: A Tiny Battery • Both inside and outside the neuron are fluids containing ions ○ Glia cells account for half of the brain's volume • Glia cells supply nourishment to neurons, help remove neurons' waste products and provide insulation around many axons The Neural Impulse: Using Energy to Send Information The Neuron at Rest: A Tiny Battery • Both inside and outside the neuron are fluids containing ions • Resting Potential of a Neu its stable, negative charge when the cell is inactive The Action Potential • Action potential: a very brief shift in the neuron's electrical charge that travels along an axon • Absolute refractory period: the minimum length of time after an action potential during which another action potential cannot being ○ Only 1 or 2 milliseconds The All-‐or-‐None Law • Either the neuron fires or it doesn't th-fringis no ha • All action potentials are the same size The Synapse: Where Neurons Meets Sending Signals: Chemicals as Couriers • The two neurons do not touch • Synaptic clef: a microscopic gap between the terminal button of one neuron and the cell membrane of another neuron • The neuron that sends the signal across the gap pr synaptic neuron, and the neuron that receives that signal p ostsynaptic neuron • Neurotransmitters: chemicals that transmit information from one neuron to another ○ Most of these chemicals are stored in small sacs called synaptic vesicles ○ Neurotransmitters may bind with special molecules in the postsynaptic cell membrane at receptor sites Receiving Signals: Postsynaptic Potentials • Postsynaptic potential (PSP): a voltage change at a receptor site on a postsynaptic cell membrane ○ Postsynaptic potentials can vary in size ○ Excitatory PSP:p ositive voltage shift that increases the likelihood that the postsynaptic neuron will fire actual potentials ○ Inhibitory PSP: negative voltage shift that decreases the likelihood that the postsynaptic neuron will fire actual potentials • Reuptake:a process in which neurotransmitters are sponged up from the synaptic cleft by the presynaptic membrane Integrating Signals: A Balancing Act • A neuron must integrate excitatory and inhibitory signals arriving at many synapses before it fires a neural impulse Neurotransmitters and Behavior synaptic cleft by the presynaptic membrane Integrating Signals: A Balancing Act • A neuron must integrate excitatory and inhibitory signals arriving at many synapses before it fires a neural impulse Neurotransmitters and Behavior • Specific neurotransmitters function at specific kinds of synapses. Acetylcholine • ACh is the only transmitters between motor neurons and voluntary muscles Monoamines • Monoamines include dopamine, norepinephrine and serotonin • Dopamineis used by neurons that control voluntary movements • Serotoninplays a role in the regulation of sleep and wakefulness ○ Some research suggests that serotonin is related to aggression in humans and animals • People who suffer from depression usually have lowered levels of activation of norepinephrine and serotonin synapses • Abnormalities in serotonin circuits also may be a factor in eating disorders and obsessive-‐compulsive disorders GABA • Another group of transmitters are amino acids • Gamma-‐aminobutyric acid(GABA) : produces only inhibitory PSPs • GABA is likely related to anxiety in humans and seizures Endorphins • Morphine exerts its effects by binding to specialized receptors in the brain • Endorphins:i nternally produced chemicals that resemble opiates in structure and effects • Endorphins and their receptors are widely distributed in the human body and contribute to the modulation of pain • Endogenous opioids also contribute to eating behavior and body's response to stress Organization of the Nervous System The Peripheral Nervous System • Peripheral nervous system: made up of all nerves that lie outside the brain and spinal cord • Nerves: bundles of neuron fibers that are routed together in the peripheral nervous system • The peripheral nervous system can be divided into the somatic nervous system and the autonomic nervous system The Somatic Nervous System • Somatic nervous system: made up of nerves that connect to voluntary skeletal muscles and to sensory receptors • Nerves that carry information from skin, muscles, and joints to central nervous and the autonomic nervous system The Somatic Nervous System • Somatic nervous system: made up of nerves that connect to voluntary skeletal muscles and to sensory receptors • Nerves that carry information from skin, muscles, and joints to central nervous system and carry commands from central nervous system to the muscles • Require two kinds of nerve fibers ○ Afferent nerve fibersaxons that carry information inward to the central nervous system from the periphery of the body ○ Efferent nerve fibera xons that carry information outward from the central nervous system to the periphery of the body The Autonomic Nervous System • Autonomic nervous system: made up of nerves that connect to the heart, blood vessels, smooth muscles, and glands • A separate system but its controlled by the central nervous system • Controls heart rate, digestion, and perspiration • Can be divided into two branches: the sympathetic division and the parasympathetic division ○ Sympathetic division: mobilizes the body's resources for emergencies ○ Parasympathetic division: generally conserves bodily resources The Central Nervous System • Central nervous system: consists of the brain and the spinal cord The Spinal Cord • Connects the brain to the rest of the body through the peripheral nervous system • Runs from the base of the brain to just below the level of the waist The Brain • Contains billions of interacting cells that integrate information from inside and outside the body, coordinate the body's actions, and enable people to talk, think, remember, plan, create, and dream The Brain and Behavior Looking Inside the Brain: Research Methods • Lesioning:d estroying a piece of the brain • Electrical stimulation of the br: nding a weak electric current into a brain structure to stimulate it The Hindbrain • includes the cerebellum and two structures found in the lower part of the brainstem: the medulla and the pons ○ Medulla: control unconscious but essential functions like breathing, maintaining muscle tone, and regulating circulation ○ Pons: includes a bridge of fibers that connects the brainstem with the cerebellum • includes the cerebellum and two structures found in the lower part of the brainstem: the medulla and the pons ○ Medulla: control unconscious but essential functions like breathing, maintaining muscle tone, and regulating circulation ○ Pons: includes a bridge of fibers that connects the brainstem with the cerebellum • Cerebellum: a relatively large and deeply folded structure adjacent to the back surface of the brainstem ○ Involved in the coordination of movement and is critical to the sense of equilibrium/physical balance The Midbrain • The segment of the brainstem that lies between the hindbrain and the forebrain • Contains an area concerned with integrating sensory processes like vision and hearing The Forebrain • The largest and most complex region of the brain, encompassing a variety of structures, including the thalamus, hypothalamus, limbic system, and cerebrum The Thalamus: A Relay Station • Thalamus:a structure in the forebrain through which all sensory information (except smell) must pass to get to the cerebral cortex The Hypothalamus: A Regulator of Biological Needs • Hypothalamus:a structure found near the base of the forebrain that is involved in the regulation of basic biological needs ○ Plays major role in the regulation of biological drives related to survival: fighting, feeding, fleeing, and "mating" The Limbic System: The Seat of Emotion • Limbic system:a loosely connected network of structures located roughly along the border between the cerebral cortex and deeper subcortical areas • Includes parts of the thalamus and hypothalamus as well as other nearby structures ○ Hippocampusp lays an important role in memory processes • Evidence suggests that the limbic system is involved in the experience of emotion ○ The amygdala may play a central role in fear responses and other emotional responses The Cerebrum: The Seat of Complex Thought • Cerebral cortex: convoluted outer layer of the cerebrum • Cerebral hemispheres: the right and left halves of the cerebrum ○ The hemispheres are separated in the center of the brain by a crevice that runs from the front to the back ○ Each hemisphere is divided into four paro besllel • Corpus callosum: major structure that connects the two cerebral hemispheres • Occipital lobe: includes the cortical area where most visual signals are sent and visual processing is begun ○ The hemispheres are separated in the center of the brain by a crevice that runs from the front to the back ○ Each hemisphere is divided into four paro besllel • Corpus callosum: major structure that connects the two cerebral hemispheres • Occipital lobe: includes the cortical area where most visual signals are sent and visual processing is begun • Parietal lobe: includes the area that registers the sense of touch • Temporal lobe:r egulates the ability to comprehend speech and language • Frontal lobe: contains the areas that control the movement of muscles • Mirror neurons: neurons that are activated by performing an action or by seeing another person perform the same action The Plasticity of the Brain • Research has shown that the structure and organization of the brain are more flexible than people previously realized ○ Experiences can affect aspects of brain structure ○ Damage to pathways or destruction of brain issue can lead to reorganization ○ The adult brain can generate new neurons Neurogenesis: the formation of new neurons § Right Brain/Left Brain: Cerebral Specialization Bisecting the Brain: Spli-tBrain Research • Split-‐brain surgery: when the bundle of fibers that connects the cerebral hemispheres is cut to reduce the severity of epileptic seizures • Each hemisphere's primary connections are to the opposite side of the body The Endocrine System: Another Way to Communicate • Endocrine system:c onsists of glands that secrete chemicals into the bloodstream that help control bodily functioning • Hormones:t he chemical substances released by endocrine glands • Much of the endocrine system is controlled by the nervous system through the hypothalamus • Pituitary gland: released a great variety of hormones that fan out within the body, stimulating actions in the other endocrine glands • Oxytocin: a hormone released by the pituitary gland, which regulates reproductive behaviors Heredity and Behavior: Is It All in the Genes? Basic Principles of Genetics • Chromosomes: threadlike strands of DNA molecules that carry genetic information • Every cell in humans contains 46 chromosomes which operate in 23 pairs. • Genes: DNA segments that serve as the key functional units in hereditary transmission • Polygenic traits: characteristics that are influenced by more than one set of • Chromosomes: threadlike strands of DNA molecules that carry genetic information • Every cell in humans contains 46 chromosomes which operate in 23 pairs. • Genes: DNA segments that serve as the key functional units in hereditary transmission • Polygenic traits: characteristics that are influenced by more than one set of genes • Most psychological characters that are affected by heredity are influenced by multiple sets of genes Detecting Hereditary Influence: Research Methods Family Studies • Family studies: when researchers assess hereditary influences by examining blood relatives to see how much they resemble one another on a specific trait • Family studies can indicate whether a trait runs in families but do not provide conclusive evidence that the trait is influenced by heredity Twin Studies • Twin studies:w hen researchers assess hereditary influence by comparing the resemblance of identical twins and fraternal twins with respect to a trait • Identical twins occur when a single fertilized egg splits for unknown reasons • Fraternal twins results are two separate eggs are fertilized simultaneously Adoption Studies • Adoption studies: assess hereditary influence by examining the resemblance between adopted children and both their biological and their adoptive parents The Interplay of Heredity and Environment • Epigenetics:t he study of heritable changes in gene expression that do not involve modifications to the DNA sequence The Evolutionary Bases of Behavior Darwin's Insights • Fitness: the reproductive success of an individual organism relative to the average reproductive success in the population • Variation in reproductive success are what really fuels evolutionary change • National selection: heritable characteristics that provide a survival or reproductive advantage are more likely than alternative characteristics to be passed on to subsequent generations and thus they to be "selected" over time Later Refinements to Evolutionary Theory • Natural selection operates on the gene pool of a population • Adaption: an inherited characteristic that increased in a population because it helped solve of problem of survival or reproduction during the time it emerged • Adaption: an inherited characteristic that increased in a population because it helped solve of problem of survival or reproduction during the time it emerged
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