Lecture 4 - Biopsychology Part 1 PDF

What is the Nervous System? Nervous System: Network of nerves and cells that transmits information Includes: Brain Spinal Cord Nerves Support (Glial) cells The CNS and PNS Peripheral...

What is the Nervous System? Nervous System: Network of nerves and cells that transmits information Includes: Brain Spinal Cord Nerves Support (Glial) cells The CNS and PNS Peripheral Central Nervous Nervous System System The nervous system has two major subdivisions: Central Nervous System (CNS): The brain and spinal cord Peripheral Nervous System (PNS): Nerves and cells connecting the rest of the body to the brain and spinal cord The PNS The Peripheral Nervous System has two further subdivisions: Somatic Nervous System: Controls voluntary, conscious actions Ex: Raising your hand, walking, playing football Autonomic Nervous System: Controls involuntary, unconscious actions Ex: Breathing, digestion, heart beat Sympathetic and Parasympathetic The Autonomic Nervous System has two further subdivisons: Sympathetic Nervous System: Prepares body for stressful situations Activates physiological arousal Activates fight-or-flight response Parasympathetic Nervous System: Calms the body back to normal after stressful situations Diminishes physiological arousal Diminishes fight-or-flight response Neurons Neurons: Cells that transmit information from the body to the brain and vice-versa Nerve cells Components of a Neuron Dendrites: “Branches” that receive information from other neurons Soma: The “body” of the neuron Contains the nucleus Nucleus: Contains genetic material of the neuron Components of a Neuron, Continued Axon: “Tail” that extends away from soma that leads to the axon terminals Axon Terminals: The endings of the axon, connect to other neurons Myelin sheath: Fatty substance that coats the axon Insulates the axon and allows faster processing How Neurons Work Resting Potential: When a neuron is “at rest,” it has a negative electrical charge Action Potential: A positive electrical charge that sweeps through neuron How Neurons Work All-or-Nothing Principle: A neuron either fires or doesn’t, no in-between Once a neuron reaches the threshold of excitation, it fires The speed, strength, and duration of action potential are unaffected by the strength of the incoming signal beyond the threshold What Happens When a Neuron Fires? Synapse: Space between axon of sending neuron and dendrites of receiving neuron Neurotransmitters: Chemicals that carry messages across the synapse Receptor Sites: Areas on the receiving neuron that accept neurotransmitters Neurotransmitters and their functions What Happens When a Neuron Fires? Reuptake: Neurotransmitters that do not land on receptor sites are reabsorbed by the sender neuron Evolution – Natural Selection Natural Selection Organisms that are well-suited to their environment survive and reproduce Organisms that are not well-suited die and do not reproduce  Genetic Variation People are different because they have different genetics But what does that mean? The Elements of Genetics Deoxyribonucleic Acid (DNA): Molecule containing genetic information Gene: Segment of a DNA chain Chromosome: Groups of genes that store and transmit genetic information A Simplified Example of Genetic Variation We all have a gene that determines our eye color I have a “blue eye” gene My wife has a “hazel eye” gene We both have an “eye color gene,” but we have different versions Alleles: Different versions of a gene  But wait! It’s more complicated than that! You have two parents, and each contribute 50% of your genetic material So, for any given trait, you have two alleles! Dominant and Recessive Alleles Brown eye alleles are dominant alleles: If an individual has a single or double copy of the allele, the associated trait is expressed Dominant alleles are symbolized by capital letters (ex: B) Blue eye alleles are recessive alleles: An individual must have a double copy of the allele for the associated trait to be expressed Recessive alleles are symbolized by lowercase letters (ex: b) Homo- and Heterozygous Alleles Homozygous Alleles: Both alleles for a trait are the same Heterozygous Alleles: The two alleles for a trait are different Genotype vs Phenotype GENOTYP E Genotype: The set of alleles and/or genes that you have Your genetic makeup Phenotype: How your genes are physically expressed What you look like PHENOTY PE Polygenic Traits Almost all human traits are polygenic Controlled by more than one gene Forexample, there isn’t a “short gene” and a “tall gene” Many genes together determine a person’s height Mutation New traits appear from errors in copying DNA Mutation: Error in DNA that causes a sudden, permanent change in a gene The Impact of Mutation Mutations are often bad Sometimes they cause an organism to die instantly Sometimes they make life much harder Mutations are sometimes good Make an organism more likely to survive More likely to pass on (mutated) genes If the mutation is advantageous enough, it will eventually become the new norm Think About Identical Twins If genetics were the only thing that mattered, identical twins would… Have all the same friends Go into the same career Have the same IQ score Get sick at the same time Die on the same day Environment Matters Things like parenting, culture, and nutrition affect how genes are expressed These things make up a person’s environment Gene-Environment Interaction: When a person’s environment affects how their genes are expressed, or vice-versa