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Lecture 9

PSYC23 - lecture 9 - 03-16-12.docx

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David Haley

PSYC23 Lecture 9031612Robert Sapolsky was a famous psychologist at Stanford and he was able to show support for this alternative view but its important that the stress system plays a big role inhibiting stress responses immune systems and that began to create a much more interesting story about how chronic stress might be bad because you know how we all know from experience that you get really stressed out like for an exam maybe you get a cold or something Its likely that you got really stressed out because you are inhibiting your immune system it is getting suppressed you know that from experience You know that that is really what is going on physiologically That was a psychological theory for many decades now theres real empirical evidence to support this So Sapolsky provided evidence of that and it showed that there are major relays in the HPA axis outside of the HPA axis that does the inhibitions So hes the one that discovered all these glucocorticoids stress perceptors in the hippocampus and thats what providing the biggest negative stress feedback that turns off the stress system As soon as it is firing up those cortisolsglucocorticoids that are aiming for the brain a lot of opportunity for them to land on the hippocampus causes the negative inhibitionSo thats good to know He articulated some of the different actions and that is we got the military analogy with our last lecture What does it have to do with the stress system Ithas to do with these alternative functions He was trying to explain that its not justthis was the classic old stuff He wanted to add all these other aspects that suppresses all these functions not only the HPA axis that suppresses all these negative feedbacks but also the immune system and there is a good evolutionary story to that If you are running away from a lion you dont need that immune system being overactivated If you really are in danger you really want all your sources to go to getting away from the lion not only defending some minor little micro that might cause an inflammation or something For example he has this alternative viewa principle suppressive aspect that Sapolsky is doing Now just a reminder that its fun to say it SAM and HPAthe two big components of the stress system includes the HPA Axis and the sympathetic adrenal medula system When you have these sympathetic nerves that are activating the release of norepinephrine then you get these actions So these are specific things that norepinephrine causes So it does cause an increase in heart rate increased breathing and sweating increased blood flow to your muscles increase in muscle strength greater alertness cognitive activity and it can even include gestinol activity Um and it is released from the medula There is a huge supply of norepinephrine thats in the medula that is activated by neurofibres descending from the brain into this region So it is different from the HPA axis HPA is all chemical messengers You can think of a tidal pool or fountain a French fountain with a bunch of concentric fountains that superimpose on each other the water fills up and it goes to a next fountain and that is the HPA Axis There is no neural connection so it is very slow But SAM is just like pressing a button and it causes norepinephrine to be released in the body So if we just step and say well what if we do have this stress response and you just look at all the components from it and all the action of all the different parts of it you can quickly see that there are a lot of things happening in the first minute You see the lion so what is happening you see the exam on the desk so what is your response And so these catecholamines are happening within the first few minutes the CRH that is one of the chemical messengers in the HPA axis that is being secreted It takes a couple more minutes naturally then ACTH is secreted and then finally where are our glucocorticoids So this is happening all within the brain right These glucocorticoids are this long trip we are going to the adrenals It takes a while for the
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