Week 6 - Psych 324
Week 6 - Psych 324 Psych 324
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This 6 page Class Notes was uploaded by Allie S on Friday October 2, 2015. The Class Notes belongs to Psych 324 at Clemson University taught by Dr. Claudio Cantalupo in Fall 2015. Since its upload, it has received 36 views. For similar materials see Brain and Behavior Psychology in Psychlogy at Clemson University.
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Date Created: 10/02/15
Chapter 6 I Motivation and Regulation of Internal States a Motivation set of factors that initiate sustain and direct behavior i Useful concept for organizing ideas about the sources of behavior ii Around because of inability to explain behavior solely in terms of external stimuli l Behaviorists are inadequate II Theoretical Approaches to Motivation a Instinct complex behavior i Automatic ii Unlearned iii Occurs in all members of a species iv Re ex Instinct No l Instincts are much more complex b Drive Theory biological i The body actively maintains physiological systems in a condition of balance homeostasis ii Departure from homeostasis lack of nutrients drop in temperature9aroused condition drive 1 Drive motivates the organism to engage in appropriate behavior drinking eating seeking warmth and restores homeostasis iii Applies to behaviors directly involved in restoring basic tissue needs c Incentive Theory sociological i Individuals are motivated by external stimuli not just internal needs 1 Money gradesincentives d Arousal Theory in between i Individuals are motivated to maintain a preferred level of arousal 1 Different people have different optimal level of arousal a Skydiving man sleeping e Drive Theory revised i Drives conditions of the tissues 1 Can t explain more complex drives well human sexual drives and hunger ii Drives state of the brain 1 Better accounts for sexual behavior even eating behavior III Simple Homeostatic drives a Many physiological systems maintain a given condition within a narrow range body temp energy reserves i Control systems operate on negative feedback loop 1 Feedback proves whereby some proportion the output of a system is passed fed back to the input in uences the output 2 Negative feedback loop feedback stabilizes the system at a given set point b Temperature regulation i Heterothermic animals reptiles externally regulated body temperature ii Homeothermic endothermic animals mammals adjust body temperature internally l Sweating vs shivering iii Where is thermostat l Hypothalamus a Preoptic area contains warmth sensitive and cold sensitive cells i Heat reducing responses sweating panting and heat conserving responses shivering Simple homeostatic drives Negative feedback loop feedback stabilizes the system at a given set point ENTRY Cf MEX Simple homeostatic drives 0 Many physiological systems maintain a given condition within a narrow range eg body temperature energy reserves Control systems operate on negative feedback loop 0 Feedback process whereby some proportion the output of a system is passed fed back to the input influences the output mm Media PreC Ptic Nucleus Hypothalamus drin Sub Fornical Organ Thalamus Hypovolemic Osmotic thirst thirst Nucleus of the Solitary TractMedulla angiotensin II Heart contains baroreceptors renin C Thirst i Osmotic thirst water content decreases inside the cell 1 Eating salty food higher concentration of NaCl in blood than inside cell H20 out of the cell by osmotic pressure 2 Picture of brain for osmotic thirst a Neurons in OVLT recognize water loss within cells and then sends signal to MPON to trigger drinking ii Hypovolemic thirst blood volume decreases due to a loss of extracellular water 1 Sweating vomiting diarrhea bleeding 2 Picture of brain with hypovolemic thirst a Baroreceptors detect BP and then sends signal to NST which sends signal to MPON b Or adrenocortical glands produces renin which synthesizes angiotensin II which travels through brain to SF0 and sends signal to MPON iii Regulated by separate systems d Hunger i More complex drive than temperature regulation and thirst 1 Set point can undergo dramatic and prolonged shifts eg obesity 2 Involves the need for a variety of different and specific kinds of nutrients a Dietary selection must distinguish between nutritious and non nutritious or toxic foods role of TASTE ii Taste 1 5 Primary tastes sweet salty sour bitter umami meaty proteins a More complex taste sensations are combinations of the 5 primaries b Nucleus of the Solitary Tract In taste bud medulla9Insula Cerebral Hemispheres 2 Contributes to dietary selection in three additional ways a Sensoryspecific satiety the more of a specific food a person eats the less appealing the food becomes i Adaptive because causes you to eat other foods attaining different nutrients ii Encourages a varied died balanced diet iii It is controlled by the Nucleus of the Solitary Tract NST in the MEDULLA b Learned taste aversions the avoidance of foods associated with illness or poor nutrition i May be one reason chemotherapy patients loose appetite c Learned taste preferences preferences for avor of foods that contain important nutrients eg vitamin B i Animals learn to prefer the avor of food enriched with thiamine presumably makes them feel better iii Digestive process 1 Begins with saliva in mouth enzymes 2 Hydrochloric acid and pepsin in stomach real chemical breakdown here a If food irritates stomach regurgitation occurs b If no irritation occurs toxins reach the area postrema of brain induce projectile vomiting 3 Most digestion occurs in small intestine esp duodenum a Carbs glucose b Proteins amino acids c Fats fatty acids and glycerol 4 Glucose AA fatty acids glycerol transferred to liver via the hepatic portal vein 5 Large intestine reabsorbs water iv Two phases of feeding cycle 1 Absorptive phase a Glucose increases parasympathetic activation pancreas secretes insulin glucose enters body cells glucose stored in liver and muscles as glycogen fat stored in adipose cells as triglycerides 2 Fasting Phase a Glucose decreases Sympathetic activation pancreas secretes glucagon glycogen transformed to glucose for brain stored fat released as fatty acids for body and glycerol for brain after conversion to glucose v Two major signals for hunger 1 Glucoprivic hunger deficit in glucose 2 Lipoprivic hunger deficit in fatty acids vi Signals for hunger 1 Low glucose and fatty acids signaled via vagus nerve to the Nucleus of the Solitary Tract NST and the Area Postrema both in the medulla 2 Info is then relayed to Arcuate Nucleus AN9 ParaVentricular Nucleus PVN and Lateral Hypothalamus LH9 Increase in release of neuropeptide Y in LH and PVN a Powerful stimulant for eating and reduces metabolism and even sexual motivation b Another powerful stimulant for eating ghrelin produced by stomach affects AN vii Signals that end eating 1 Stretch receptors in stomach signal via vagus nerve to medulla NST and area Postrema9decrease of neuropeptide Y in PVN and LH Cholecystokinin CCK peptide hormone released when food passes through the duodenum vagus nerve medulla decrease of neuropeptide Y in PVN and LH Peptide YY336PYY intestine secreted hormone reaches Arcuate Nucleus through bloodstream slower action than CCK High levels of nutrients in blood detected by liver vagus nerve medulla NST and area Postrema9decrease of neuropeptide Y in PVN and LH e Long term regulation of body fat i Leptin hormone secreted by fat cells 1 2 3 4 Amount of leptin in blood is proportional to percent of body fat Increased leptin in blood decrease in neuropeptide Y in PVN and LH Decreased leptin in blood increase in neuropeptide Y in PVN and LH Leptin levels is about 4 times higher in obese than non obese individuals may have fewer active leptin receptors in PVN and LH
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