Criado por Zsofi Dombi
mais de 6 anos atrás
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Questão | Responda |
Stress definition | A real or interpreted threat to the physiological or psychological integrity of an individual that results in physiological and / or behavioral response |
Historical definitions of stress | 1. Cannon = stimulus that challenges the organism’s homeostasis 2. Selye = the sum of non-specific response of an organism to any challenges |
The elements of stress | 1. Input / stressor 2. Stress processing 3. Output / stress response |
Types of stressors | 1. Systemic stressor = physiological injury 2. Psychogenic stressor = interpersonal conflict or time pressure |
Stress response definition | A physiological reaction that occurs in response to perceived harmful event / attack / threat to promote survival |
Types of stress response | 1. Fast sympathetic nervous system response 2. Slow HPA axis response |
Fast stress response definition | Short-term response involving norepinephrine release |
Slow stress response definition | Long-term response involving the induction of a hormone cascade |
Steps of the slow stress response | 1. Release of CRF from the paraventricular nucleus of the hypothalamus 2. CRF binding to anterior pituitary and release of ACTH 3. ACTH binding to adrenal cortex and stimulation the synthesis and secretion of glucocorticoids 4. Glucocorticoid results in energy mobilization |
Negative feedback control of slow stress response | Glucocorticoids bins to its receptors in the hippocampus, hypothalamus and anterior pituitary and inhibits the secretion of CRF and ACTH |
The role of the hippocampus in the slow stress response | By containing the highest concentration of GR and MR in the body it is informed by the current state. As it has string inhibitory connections with the hypothalamus it can inhibit the CRF production of the PVN. |
The Yerkes-Dodson law (1908) | Describes the relationship between arousal and performance - increased arousal up to a point increase performance too |
Sandi eat al (1997) | - rate trained for spatial learning task in water maze - two conditions: cold and warm water - results: cold water increased performance |
Kim and Diamond (2002) | - rats trained in radial arm water maze - study description: 1, learning 2, removal 3, retention - two conditions: home cage or predator exposure during removal - result: memory distortion in predator exposure in difficult task |
Woodson et al (2003) | - rats trained to acquire spatial working memory - exposed to a female rat or a cat - same increase in corticosterone - but only predator stress impaired working memory |
Korz & Frey (1993) | - weak tetanization if dentate gyrus - rats exposed to 2 stress inducing procedures:handling and swimming - handling: reversed LTP - swimming + handling: elicited protein synthesis - blockage of GR prevented reversal of LTP by handling - inactivation of MR hindered LTP prolongation by swimming |
Ajai Vyas et al (2002) | - examined the effects of two different models of chronic stress - chronic immobilization: induced dendritic atrophy and de-branching of CA3 pyramidal neurons in the hippocampus - chronic unpredictable stress: little effect on CA3 pyramidal neurons, but reduced open-arm activity in EPM |
Pawlak et al (2005) | - little known about the molecular mediatiors of functional deficits in the hippocampus - report big pre- and post-synaptic effects of chronic stress: reduction in NMDA receptors, dendritic spines - at behavioral level: impaired acquisition but not retrieval of hippocampal spatial learning |
Effects of stress on the PFC and amygdala | PFC: similar to the hippocampus Amygdala: formation of new dendritic spines and does not affect contextual fear conditioning |
Shors et al (2002) | Reduction in new neurons associated with reduction in fear acquired |
Mitra et al (2005) | Investigated the efficacy of aversive experience - acute and chronic immobilization - chronic: robust increase in spine density - acutely: fail to affect density only 10 days later |
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