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CH2 Textbook Notes

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University of Toronto St. George

CHAPTER 2 CONTEMPORARY THEORIES OF ABNORMALITY - theory: a set of ideas that provide a framework for asking questions about a phenomenon, as well as gathering and interpreting information about that phenomenon - Albert Ellis suffered a fear of public speaking - he believed his fears were due to irrational beliefs - other theories would suggest alternative causes of his fears - biological approach would suggest his symptoms were caused by a biological factor e.g. genetic vulnerability to anxiety - psychological approach suggests symptoms are rooted in psychological factors e.g. belief system, early childhood experiences - social approach would look at his interpersonal relations and social environment - most theories over history searched for one factor that causes people to develop a disorder - contemporary theorists recognize that there are often many pathways that lead to the development of a specific disorder - vulnerability stress model: a person must carry a vulnerability to the disorder in order to develop it - it can be biological (genetic predisposition), psychological (personality trait), social factor (poor interpersonal relationships) - to develop the disorder, person must experience some type or stress or trigger - biological (illness), psychological (violation of trust), social factor (traumatic event) - feedback effects: change in one factor result in changes in a second factor which feed back to change the first factor again Biological Approaches Structural Brain Abnormalities - people who suffer damage to the brain (lesions) or who have major abnormalities in the structure of the brain often show problems in psychological functioning - location of structural damage influences the psychological problems one can have - cerebral cortex: area involved in many advanced thinking processes - hypothalamus: regulates eating, drinking, and sexual behaviour, influences basic emotions - stimulation in certain areas produce pleasure whereas in other areas produce pain - limbic system: collection of structures closely interconnected with the hypothalamus and appear to exert additional control over some instinctive behaviours - other major structures of the brain (figure 2.5 pg34) - corpus callosum: bridge of fibres passing information between the two cerebral hemispheres - thalamus: relay centre for cortex; handles incoming and outgoing signals - cerebellum: involved in balance and control of movement www.notesolution.com - medulla: responsible for regulating largely unconscious functions e.g. circulation, breathing - pons: involved in sleep and arousal - reticular formation: network of neurons related to sleep, arousal, and attention - spinal cord: responsible for communication between brain and rest of body; involved with simple reflexes Biochemical Causes of Abnormality - neurotransmitters: biochemicals that act as messengers, carrying impulses from one neuron (nerve cell) to another in the brain and in other parts of the nervous system - each neuron has a cell body and dendrites which receive impulse from adjacent neurons - impulse then travels down the length of the axon to small swellings at the ends called synaptic terminals - there is a slight gap between the synaptic terminals and adjacent neurons called the synaptic gap, or synapse - neurotransmitter is released into the synapse and then binds to receptors, molecules on membranes of adjacent neurons - binding stimulates adjacent neurons to become more negatively or positively charged Neurotransmitter Theories - too much or too little of certain neurotransmitters in the synapses causes specific types of psychopathology - amount of neurotransmitter in synapse can be affected by - reuptake: when the initial neuron releasing the neurotransmitter reabsorbs the neurotransmitter, decreasing the amount left in the synapse - degradation: when the receiving neuron releases an enzyme into the synapse breaking down the neurotransmitter into other biochemicals - both happen naturally, when one or both malfunction, result in abnormally highlow levels - psychological symptoms may also be linked to the number and functioning of receptors for neurotransmitters on the dendrites - if there are too few receptors or receptors arent sensitive enough, the neuron will be unable to make adequate use of the neurotransmitter available in the synapse - if there are too many receptors or they are too sensitive, neuron may be overexposed - serotonin: regulates emotions and impulses e.g. aggression - travels through many key areas of the brain - dopamine: prominent in areas of brain that regulate our experience of reinforcement or rewards, affected by substances that we find rewarding - important to functioning of muscle systems - norephinephrine: produced mainly by neurons in brain stem - cocaine and amphetamines prolong the action by slowing its reuptake process - low levels cause a persons mood level to be depressed www.notesolution.com
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