PSYB64H3 Chapter Notes - Chapter 9: Thyroid, Raynaud Syndrome, Blood Vessel
18 Oct 2015
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The poa contains three types of neurons: (1)warm sensitive, (2)cold sensitive, and (3)temperatures insensitive (1) warm sensitive: increase their firing rates and inhibit cold sensitive neurons as core temp. increases, as temp. drops the firing rates of warm sensitive neurons decrease, reducing their inhabitation of the cold sensitive neurons which respond by increasing their firing rates. (2)temperature insensitive neurons: retain a fairly steady rate of responding under all temperature conditions, temperature set points possibly reflect a comparison of the activity of temperature sensitive and temperature insensitive neurons. Hunger: (1) low fat stores, low levels of leptin, activation of npy, agrp, ghrelin, and orexins (cid:224) eating is initiated (2) parasympathetic system is activated and body stores nutrients (3) tsh and acth are suppressed: results in lowered metabolic activity (4) agrp blocks mc4 receports in lateral hypothalamus: stimulates eating behaviour (5) body fat levels increase, leading to satiety.
