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Lecture

Lecture #3- Biological Foundations.docx

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Department
Psychology
Course
PSY100H1
Professor
Ashley Waggoner Denton
Semester
Fall

Description
Lecture #3: Biological Foundations People are using psychological disorders as escape goats for committing crimes. Behaviour cannot be explained through a single-cause, there are always many more sides to the story. There are four factors that influence behaviour: 1. Heredity 2. Biology 3. Environment 4. Culture The nervous system controls the body’s electrochemical communication. The central nervous system (CNS) is composed of the brain and spinal cord. This contains 99% of the nerve cells. The peripheral nervous system (PNS) is composed of the somatic (deals with external world) and autonomic nervous system (deals with internal world). The autonomic nervous system is then broken down into the sympathetic and parasympathetic nervous system. Neurons operate through electrical impulses. Three types of neurons:  Sensory Neurons (afferent)  Motor Neurons (efferent)  Interneurons Integrates signal Receive Terminal electrochemical button signals Axon: propagates the nerve impulse Increases the rate Tiny space between of information adjacent neurons transfer A neuron can receive an excitatory signal, which increases the likelihood of firing by depolarizing the neuron (making the internal environment positive). An inhibitory signal decreases the likelihood of firing by hyperpolarizing the neuron (making the internal environment more negative). A neuron will fire when it reaches a threshold value. In a resting neuron, the internal environment is usually - 70mV. Neurons operate by certain principles:  All-Or-None: A neuron fires with the same potency each time, either it fires or it doesn’t  no in-between. It can only vary on how often it fires.  Action Potential: The neural impulse across the axon releases neural transmitters (chemicals) by the terminal buttons into the synapse to be received by the adjacent neuron.  Resting Membrane Potential: During the resting phase, the potassium channels are open and the sodium channels are closed. This allows for potassium to diffuse into the cell and the internal environment in negative. The internal environment is always “more negative” than the external environment.  Depolarization: The internal environment reaches the threshold value and the sodium channels suddenly open. Sodium floods into the cell and potassium flows out. This causes the internal environment to become positive.  Repolarization: Post firing; the sodium channels close and the internal environment is returning to normal. Neurotransmitters are stored in vesicles in the terminal buttons. The action potential of the last cell in the neuron causes the vesicle to fuse with presynaptic membrane and release contents into the synapse. The postsynaptic membrane of the adjacent neuron’s dendrite receives the neurotransmitter and degrades it via an enzyme. Some common neurotransmitters are:  Acetylcholine: Motor control at junctions between muscles o Botox prevents acetylcholine from working  Epinephrine: adrenaline  Norepinephrine: arousal and alertness  Serotonin: emotional states  Dopamine: Reward system  GABA: inhibitor  Glutamate: excitatory Two Types of Drugs: 1. Agonist: enhance neurotransmitter action by: o Increasing release rate o Blocking reuptake o Mimicking (and activating)  Ex.  cocaine, methamphetamine 2. Antagonist: inhibit neurotransmitter action by: o Blocking release o Destroying neurotransmitter in the synapse o Mimicking (and blocking binding)  Ex.  Beta-blockers (prevent epinephrine to help heart), botox The Brain:  Brainstem o Life sustaining functions of the autonomic nervous system o Composed of: medulla oblongata, pons, midbrain o Alertness and sleep o Network of neurons that stem into the upper brain  Cerebellum o Coordinated movement and balance o Alcohol affects the cerebellum  Subcortical Structures: Hypothalamus o Master regulatory structure o Connects nervous system to the endocrine system o Vital to the Four F’s: fighting, fleeing, feeding and …mating  Subcortical Structures: Thalamus o Gateway to the brain o Cognitive functioning o Relay station  Handles all incoming sensory information, EXCEPT SMELL, and redirects to the appropriate location o Closes to keep us sleeping o Tatiana and Krista Hogan  conjoined twins who share a thalamus. They share all incoming information; delayed on language.  Subcortical Structures: Hippocampus o Storage of new memories o Shaped like a seahorse o London cab drivers  To be a cab driver in London, one has to pass the “Knowledge of London” test, which is basically memorizing a very detailed map of everything in London. After memorizing, studies show an increase in the size of the hippocampus. This con
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