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Chapter 17

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Western University
Psychology 2220A/B
Scott Mac Dougall- Shackleton

Chapter 17: Biopsychology of Emotion, Stress, and Health FEAR, DEFENSE, AND AGGRESSION • Fear is the emotional reaction to threat; it is the motivating force for defensive behaviours • Defensive behaviours are behaviours whose primary function is to protect the organism from threat or harm • Aggressive behaviours are behaviours whose primary function is to threaten or harm • Types of Aggressive and Defensive Behaviours • Blanchard and Blanchard have derived rich descriptions of rat intraspecific aggressive and defensive behaviours by studying the interactions between the alpha male - the dominant male - of an established mixed-sex colony and a small male intruder • Categories of rat aggressive and defensive behaviours are based on three criteria 1. Their topography (form) 2. The situations that elicit them 3. Their apparent function • The analysis of aggressive and defensive behaviours has led to the development of the target-site concept - the idea that the aggressive and defensive behaviours of an animal are often designed to attack specific sites on the body of another animal while protecting specific sites on its own • Lateral septal lesions do not increase aggression • Aggression and Testosterone • Social aggression in many species occurs more commonly among males than among females is usually explained with reference to the organizational and activational effects of testosterone • Comparative research literature on testosterone and aggression • Testosterone increases social aggression in the males of many species; aggression is largely abolished by castration in these same species • In some species, castration has no effect on social aggression; in still others, castration reduces aggression during the breeding season but not at other times • The relation between aggression and testosterone levels is difficult to interpret because emerging in aggressive activity can itself increase testosterone levels • The blood level of testosterone, which is the only measure used in many studies, is not the best measure • In human males, aggressive behaviour does not increase at puberty as testosterone levels in the blood increase; aggressive behaviour is not eliminated by castration; and it is not increased by testosterone injections that elevate blood levels of testosterone STRESS AND HEALTH • When the boy is exposed to harm or threat, the result is a cluster of physiological changes that is generally referred to as the stress response • All stressors produce the same core pattern of physiological changes, whether psychological or physical • However, it is chronic psychological stress that has been most frequently implicated in ill heath Chapter 17: Biopsychology of Emotion, Stress, and Health • The Stress Response • In the short term, it produces adaptive changes that help the animal respond to the stressor in the long term, however, it produces changes that are maladaptive • Selye attributed the stress response to the activation of the anterior-pituitary adrenal-cortex system • Conclude that stressors acting on neural circuits stimulate the release of adrenocorticotropic hormone (ACTH) from the anterior pituitary, that the ACTH in turn triggers the release of glucocorticoids produce many of the components of the stress response • Stressors activate the sympathetic nervous system, thereby increasing the amounts of epinephrine and norepinephrine released from the adrenal medulla • The major feature of Selye’s landmark theory is its assertion that both physical and psychological stressors induce the same general stress response • Stress responses are complex and varied, with the exact response depending on the stressor, its timing, the nature of the stressed person, and how the stressed person reacts to the stressor • Brief stressors produce physiological reactions that participate in the body’s inflammatory responses • Found that brief stressors produced an increase in blood levels of cytokines, a group of peptide hormones that are released by many cells and participate in a variety of physiological and immunological responses, causing inflammation and fever • Animal Models of Stress • Stress research on nonhumans tended to involve extreme forms of stress such as repeated exposure to electric shock or long periods of physical restraint • Responses to extreme stress tend to make normal variations in the stress response, and it is difficult to relate the results of such studies to common human stressors • When conspecific threat becomes an enduring feature of daily life, the result is subordination stress • Psychosomatic Disorders: The Case of Gastric Ulcers • Gastric ulcers were one of the first medical disorders to be classified as psychosomatic • Gastric ulcers are painful lesions to the lining of the stomach and duodenum, which in extreme cases can be life-threatening • H.pylori damage the stomach wall or that antibiotic treatment of gastric ulcers helps many sufferers • H. pylori infection alone is insufficient to produce the disorder in most people • Another factor that increases the susceptibility of the stomach wall to damage from H.pylori appears to be stress • Psychoneuroimmunology: Stress, the Immune System, and the Brain • The discovery that stress can increase susceptibility to infection led to the emergence of a new field of research: psychoneuroimmunology - the study of interaction among psychological factors, the nervous system and the immune system • Immune System Chapter 17: Biopsychology of Emotion, Stress, and Health • Immune system keeps you body from being overwhelmed by invaders, but, before it can take any action against an invading microorganism, the immune system must have some way of distinguishing foreign cells from body cells • That is the function of antigens - protein molecules on t
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