-thirst (slide will be on bb)there are two types of thirst, we cannot tell the difference between the twoosmotic thirst: water content decreases inside the cellwhy is it called this? Say you eat something really salty, are you going to feel thirsty after awhile, yesthe moving of water out of the cell cause osmotic pressure (NaCl moves out and water along with it)eating salty food---higher concentration of NaCl in the blood than inside the cell----water drawn out of the cell by osmotic pressurehypovolemic thirst: blood volume decreases due to loss of extracellular waterfrom loss of blood, vomiting, sweatingthese two are regulated by separate systems-osmotic thirstneurons are found in the thin band of gray matter that is called OVLTmedian preoptic nucleus of the hypothalamus: anytime neurons become active here that is when you feel thirsty-hypovolemic thirstreceptors are not found in the brainsome are found in the heart (baroreceptors) that detect pressurehas multiple pathwaysaxons from the medulla (nucleus of the solitary tract) that leads to the median preoptic nucleus-so they both end up at the median preoptic nucleus and this why you cannot tell the difference-the adrenal hormone stimulated renin: catalyzes or stimulates angiotensin II which is also dumped into the blood supply and reach the subfornical organ, the neurons become active and then they send a signal to the median preoptic nucleus-angiotensin II is the hormone directly activating the subfornical organ-hungermore complex drive than temperature regulation and thirstthirst is involved in just water, hunger is involved in the regulation of much more nutrientsset point can undergo dramatic and prolonged shifts (obesity)involves need for a variety of different and specific kinds of nutrientsdietary selection: must distinguish between nutritious and non-nutritious foodssense of taste one of the oldest senses, chemical sense-tastethere are five primary tastes----sweet, salty, sour, butter, umamimore complex taste sensations are combinations of the 5 primariestaste buds….each tiny bud is a papillanucleus of the solitary tract (part of the medulla) goes to the insula which is In the cerebral hemispherescontributes to dietary selection in three additional wayssensory specific satiety: the more of a specific food a person eats, the less appealing the food becomes (not permanent, happens in a few seconds and goes away quickly)encourages a varied diet----balanced dietit is controlled by the nucleus of the solitary tract in the medullathis is a type of learning that is innatelearned taste aversion: the avoidance of foods associated with illness or poor nutritionmay be one reason chemotherapy patients loose appetitelearned taste preferences: preference for flavor of food that contain important nutrients (vitamin B)have seen this is animal modelscan learn through differences in taste to discriminate between food that contain certain type of nutrients like vitaminsanimals learn to prefer the flavor of foods enriched with thiamine presumably makes them betterThe digestive process-begins with saliva in the mouth that contains enzymeshydrochloric acid and pepsin break down food even further in the stomachif food irritates the stomach, regurgitation occursif no irritation occurs, toxins reach the area postrema of the brain---induce projectile vomiting-most digestions occurs in the small intestine (esp duodenum)carbs---glucoseproteins---amino acidsfats----fatty acids-transferred to the liver via the hepatic portal vein-then goes through the large intestine which reabsorbs as much water as possibletwo phases of feeding cycle-absorptive phasestarts when receptors in body detect an increase of glucose on bloodthis causes activation of the parasympathetic nervous systemso the pancreas secretes insulin to break down glucoseglucose enters body cells, stored in the liver and muscles as glycogen, fat stored in adipose cells as triglycerides-fasting phasestarts when glucose levels decreasesympathetic activation is triggered so the pancreas secretes glucagon which triggers the opposite set of reactions insulin mediateglucagon brings glucose out of storageso glycogen transformed to glucose, stored fat release as fatty acids and glycerol (for brain after conversion to glucose)two major signals for hunger-glucoprivic hunger----deficit in glucose-lipoprivic hunger---deficit in fatty acidssignals for hunger-low glucose and fatty acids signaled via vagus nerve to the nucleus of the solitary tract and the area postrema (both in the medulla)-info is then relayed to the arcuate nucleus and it send info to the paraventircular nucleus of the hypothalamus and the lateral hypothalamus-so when the PVN and LH become active we see an increase of neuropeptide Y in LH and PVNpowerful stimulant for eating and reduced metabolism (and even sexual motivation)another powerful stimulant for eating: ghrelin (produced by stomach, affects ANsignals that end eating-stretch receptors in the stomach---signal via vagus nerve to medulla (NST and area postrema)----decrease of neuropeptide Y in PVN and LH (tend to hyperpolarize the neurons in that region which should cause you to feel less hungry)-CCK- peptide hormone released when food passes through the duodenum---vagus nerve----decrease of neuropeptide Y in the PVN and LH-peptide YY 3-36 PYY intestine-secreted hormone----reaches arcuate nucleus through bloodstream ---slower action than CCK-high levels of nutrients in blood----detected by liver---vagus nerve—medualla (NST and area postrema)----decrease of neuropeptide Y in PVN and LHExam Two Information:- Chapter 3 (2-18-14) 74-78 (Starting at “development and change in the NS” excluding “How Experience modifies the NS”- Chapter 5 pp. 126-146 (excluding “The Role of Genes in Addictions”)- Chapter 6 pp. 156-171- Chapter 7 pp. 190-197- Chapter 8 pp. 224-227 (excluding The Emotional Brain)- Development of the Nervous Systemo Forebrain, midbrain, hindbraino Growth happens at different rateso Growth Phases:o Proliferation: Neurons divide and multiply at extreme rate Only stages that cells can divideo Migration: Neurons migrate to final location by climbing radial glial cellso Circuit Formation: Neurons send developing axons to make synapseswith their target cells Growth cone develops at tip of developing axons and move toward final targets using chemical/molecular (like a nose)o Circuit pruning Extra neurons that have developed die Eliminates