Copyright © 2005 Pearson Education Canada Inc. 1 Evolutionary Psychology The biological theory of evolution assumes natural selection is a key factor in how a species changes over time Characteristics that help an organism survive are passed on to future generations
Copyright © 2005 Pearson Education Canada Inc. 2 Evolutionary Psychology Adaptation occurs when a trait has increased in a population Individuals with the adaptive trait are more likely to survive and reproduce
Copyright © 2005 Pearson Education Canada Inc. 3 The Genome The genome is the total DNA blueprint of traits that can be inherited Genetic mapping is the dividing the chromosomes into smaller fragments that can be mapped to reflect their respective locations
Copyright © 2005 Pearson Education Canada Inc. 4 The Basics of Genetics Behavioural Genetics is the study of both genetic and environmental contributions to variations in human behaviour Heritability is the proportion of variation in a trait determined by heredity
Copyright © 2005 Pearson Education Canada Inc. 5 The Basics of Genetics Each human cell contains 23 pairs of chromosomes Chromosomes are strands of DNA that carry genes
Copyright © 2005 Pearson Education Canada Inc. 6 The Basics of Genetics Genes are the fundamental units of heredity Genetically determined traits are controlled by pairs of genes
Copyright © 2005 Pearson Education Canada Inc. 7 The Basics of Genetics A genotype is a person’s genetic make- up, which is fixed at birth The phenotype is a person’s observable characteristics
Copyright © 2005 Pearson Education Canada Inc. 8 The Basics of Genetics Recessive members of gene pairs appear in the phenotype only if both members of the pair are recessive A dominant gene is always expressed if it is inherited
Copyright © 2005 Pearson Education Canada Inc. 9 The Neuron The neuron is the basic unit of the nervous system
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Copyright © 2005 Pearson Education Canada Inc. 12 Types of Neurons Afferent neurons carry messages to the brain and spinal cord Efferent neurons carry messages from the brain and spinal cord to other structures of the body
Copyright © 2005 Pearson Education Canada Inc. 13 Figure 2.2 The Action of Afferent and Efferent Neurons
Copyright © 2005 Pearson Education Canada Inc. 14 Types of Neurons Sensory neurons are afferent neurons that carry information from the sense organs to the brain Motor neurons are efferent neurons that carry information from the brain and spinal cord to muscles and glands Interneurons connect other types of neurons
Copyright © 2005 Pearson Education Canada Inc. 15 Electrochemical Processes The electrical process is created by a thin membrane around the neuron In the normal resting state, the interior of a neuron carries a negative electrical charge
Copyright © 2005 Pearson Education Canada Inc. 16 Electrochemical Processes Activity within neurons is electrical Activity between neurons is chemical
Copyright © 2005 Pearson Education Canada Inc. 17 Electrochemical Processes The electrical process is created by a thin membrane around the neuron In the normal resting state, the interior of a neuron carries a negative electrical charge
Copyright © 2005 Pearson Education Canada Inc. 18 Electrochemical Processes The exterior carries a positive electrical charge The difference in interior and exterior charges creates a state of polarization
Copyright © 2005 Pearson Education Canada Inc. 19 Electrochemical Processes The action potential (or spike charge) is an electrical current that travels down an axon It is initiated by a rapid reversal of the polarization of a neuron’s cell membrane
Copyright © 2005 Pearson Education Canada Inc. 20 Electrochemical Processes When stimulated to the action potential, gates in a neuron’s membrane open The action potential occurs in an all-or- none fashion
Copyright © 2005 Pearson Education Canada Inc. 21 Figure 2.5 Generation of an Action Potential
Copyright © 2005 Pearson Education Canada Inc. 22 Electrochemical Processes After firing, a refractory period occurs Normal stimulation will not activate the neuron
Copyright © 2005 Pearson Education Canada Inc. 23 Neurotransmitters When an action potential moves down an axon, it causes the release of neurotransmitters
Copyright © 2005 Pearson Education Canada Inc. 24 The Neural Synapse The synapse is a small space between the axon terminals of one neuron and receptor sites of another
Copyright © 2005 Pearson Education Canada Inc. 25 Figure 2.4 The Synapse
Copyright © 2005 Pearson Education Canada Inc. 26 Neurotransmitters Neurotransmitters are chemicals that move across the synaptic space They communicate with other neurons by binding to receptors
Copyright © 2005 Pearson Education Canada Inc. 27 Neurotransmitters After communicating, the neurotransmitter may be neutralized or taken back by the neuron that released it The process of taking neurotransmitters back in is called reuptake
Copyright © 2005 Pearson Education Canada Inc. 28 Neurotransmitters A change in the membrane of a neuron after receiving neurotransmitters is called a postsynaptic potential
Copyright © 2005 Pearson Education Canada Inc. 29 Neurotransmitters Sometimes neurotransmitters cause a neuron to fire more easily They create an excitatory postsynaptic potential
Copyright © 2005 Pearson Education Canada Inc. 30 Neurotransmitters At other times neurotransmitters inhibit a neuron from firing This is an inhibitory postsynaptic potential
Copyright © 2005 Pearson Education Canada Inc. 31 Some Neurotransmitters GABA Serotonin Acetylcholine Endorphins