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Lecture 10


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Rutsuko Ito

lec10 stress and arousal lecture overview what is stress? acute stressors 1. acute stressors are an adaptive fight / flight response 2. selective diversion of energy to organs needed for survival chronic stressors 1. chronic stressors affect the homeostatic system a. they are dangerous because they tip the stress response system out of control 2. social interactions are important in the regulation of stress a. social stress is just as disruptive as predator stress chronic / life stressors physiological response to stressor adrenaline / cortisol response 1. in fight / flight phase a. you would see the release of adrenaline b. then a lower activation of cortisol response i. even when the stressor is gone 2. what happens in repeated stressors? a. adrenaline response is the same b. cortisol does not come down to baseline (steadily increases) selye's general adaptation syndrome 1. alarm reaction a. fight / flight phase 2. stage of resistance a. stress activated b. but the response's function is to stabilize body's response to stress i. can be neural, etc short term stress response alarm phase (fight or flight) 1. can be thought as an arousal phase or fight / flight phase 2. counter homeostatic a. body is getting ready to counteract something b. it prepares the body's resources 3. the hypothalamus coordinates the activation of stress response through direct neural connections adrenal medulla activation 1. stressors stimulate preganglionic sympathetic nerves to release NA /A from adrenal medulla 2. cortex and medulla have different functions / different secretions adrenaline / noradrenaline release 1. hypoxic stress / oxygen deprivation 2. adrenaline is stored more than noradrenaline 3. in chronic stress a. depletion of NA / A will occur because the stores are gone b. small stores of NA / A came in late (3:39pm) physiological response 1. encouraging the stimulation of sympathetic activity 2. encourage the increase of availability of energy substrate 3. metabolism is encouraged a. breaking down fat and fatty acids b. readily available glucose for functioning of the CNS 4. decreased parasympathetic response a. decreases GI motility and secretion noradrenaline release in CNS 1. NA pathways from locus ceruleus and reticular formation noradrenaline 2. important in cognitive functions 3. particularly responsive to salient stimuli and novelty 4. activation of the NA system that aids in the improved effects on performance and attention a. as a result of acute stress resistance (coping) phase resistance phase reaction 1. if stress is longer lasting  activation of the HPA axis 2. this phase is the body's homeostatic response to stresses 3. sympathetic activation activates the kidney to secrete renin  ultimately water retention as a downstream effect  to maintain high blood pressure and water supply HPA axis activation 1. must know this in detail* 2. spelled out everything on this slide -- need to know the terms and the fully spelled out words 3. HPA activation  release of glucocorticoids from the adrenal cortex a. this is a negative feedback system i. acts to negatively inhibit further release 4. mechanism a. stressor b. PVN neurons activated i. how they are turned on are not well known c. secretion of corticotropin releasing hormone (CRH) and vasopressin into portal vein d. hormones travel down to the anterior pituitary gland e. results in the release of ACTH f. acts on the adrenal cortex to release glucocorticoids g. glucocorticoids inhibit further release of i. ACTH ii. CRH production in PVN limbic regulation of HPA axis 1. hippocampus is important regulator of HPA axis a. suppresses the HPA system 2. amygdala is also a big player in regulating the HPA axis a. stimulates the HPA system and stress response actions of cortisol 1. slow acting / long lasting response 2. range of actions of cortisol a. encourages the availability of glucose by breaking down proteins / amino acids / fatty acids b. maintains solutes in the blood stream c. inhibits the human immune response to reduce inflammation i. because inflammation can be disruptive to functioning stress and cognition 1. effect of stress response and neurotransmitter release on measures of learning 2. administering cortisol / NA / AAFTER learning
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