What is the genetic basis of psychological science Chromosomes structures within the cell body that are made up of genes human has 23 pairs organism Gene the unit of heredity that determines a particular characteristic in an Heredity involves passing along genes through reproduction o Dominant gene and recessive gene o Genotype and phenotype Genotype the genetic constitution determined at the moment of Phenotype observable physical characteristics that result from both genetic and environmental influences conception o Polygenic effects Genotypic variation is created by sexual reproduction o Random cell division before reproduction allows genotypic variation o Mutation can be adaptive or maladaptive Industrial melanism adaptive Sickle cell disease maladaptive o Recessive genes can survive in the gene pool as it does not interfere with most people s health o Dominant genes cannot survive in the gene pool as it is lethal for most of o Behavioral genetics the study of how genes and environment interact to their carriers Genes affect behavior influence psychological activity o Behavioral genetics methods Twin studies Monozygotic twins twin siblings who result from one zygote splitting in two and therefore share the same genes Dizygotic twins twin siblings who result from two separately fertilized eggs Adoption studies o Understanding heritability Heritability a statistical estimate of the variation caused by differences in heredity in a trait within a population It refers to populations Social and environmental contexts influence genetic expression o Nature and nurture together affect behavior they are inextricably entwined Genetic expression can be modified How does the nervous system operate Neurons are specialized for communication o Neurons the basic units of the nervous system it operates through electrical impulses which communicate with other neurons through chemical signals Neurons receive integrate and transmit information in the nervous system o Types of neurons Sensory neurons afferent neurons they detect information from the physical world and pass that information along to the brain via the spinal cord Motor neurons efferent neurons they direct muscles to contract or relax thereby producing movement Interneurons they integrate neural activity within a single area rather than transmitting information to other brain structures or to other body organs Together sensory and motor neurons control movement o Neuron structure Dendrites branchlike extensions of the neuron that detect information from other neurons Cell body in the neuron where information from thousands of other neurons is collected and processed Axon a long narrow outgrowth of a neuron by which information is transmitted to other neurons Terminal buttons small nodules at the ends of axons that release chemical signals from the neuron to the synapse Synapse the site for chemical communication between neurons which contains extracellular fluid Myelin sheath fatty material made up of glial cells that insulates the axon and allows for rapid movement of electrical impulses along the axon Nodes of Ranvier small gaps of exposed axon between the segments of myelin sheath where action potentials are transmitted o The resting membrane potential is negatively charged Resting membrane potential the electrical charge of a neuron when it is not active Electrical charge inside the neuron is slightly more negative than the one outside Polarization changing the differential electrical charge inside and outside the neuron This creates the electrical energy necessary to power o The roles of sodium and potassium ions the firing of the neuron Two ions that contribute to a neuron s resting potential Ion flow is affected by the cell membrane s selective permeability There are more potassium inside the neuron than sodium This imbalance contributes to polarization Action potentials cause neural communication o Action potential the neural impulse that passes along the axon and subsequently causes the release of chemicals from the terminal buttons o Changes in electrical potential lead to action Excitatory signal Inhibitory signal It depolarizes the cell membrane increasing the likelihood that the neuron will fire It hyperpolarizes the cell and decreases the likelihood that the neuron will fire The electrical charge inside the cell during this process starts out slightly negative in its initial resting state then becomes positive as it fires and allows more positive ions inside the cell and then through natural restoration it goes back to its slightly negative resting state o Action potentials spread along the axon Propagation cell membrane s depolarization Myelin sheath allows impulse to jump from one node to another o All or none principle the principle whereby a neuron fires with the same potency each time although frequency can vary Neurotransmitters bind to receptors across the synapse o Presynaptic neuron that sends the signal and postsynaptic neuron that o Neurotransmitters a chemical substance that carries signals from one o Receptors specialized protein molecules located on the postsynaptic receives the signal neuron to another membrane Binding produces an excitatory or inhibitory signal for the postsynaptic neuron o Neurotransmitters bind with specific receptors Once neurotransmitters are released into the synapse they continue to fill and stimulate that receptor and they block new signals until their influence is terminated Reuptake the process whereby a neurotransmitter is taken back into the presynaptic terminal buttons thereby stopping its activity Enzyme deactivation Autoreception Neurotransmitters influence mind and behavior o Agonists drugs that enhance the actions of a specific neurotransmitter o Antagonists drugs that inhibit the action of a specific neurotransmitter o Types of neurotransmitters Acetylcholine ACh Whether Ach s effects will be excitatory or inhibitory depends on the receptors Motor control over muscles Mental process such as learning memory sleeping and dreaming Monoamines major functions are to regulate states or arousal and affect and to motivate behavior Epinephrine Energy Adrenaline rushes Norepinephrine Arousal and vigilance Serotonin Emotional states and impulsiveness Dreaming Dopamine Reward and motivation Motor control over voluntary movement GABA gamma aminobutyric acid Primary inhibitory transmitter Inhibition of action potentials Anxiety and intoxication Glutamate Primary excitatory