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Chapter 3

Motivation and Emotion - Chapter 3

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Department
Psychology
Course
PS264
Professor
Camie Condon
Semester
Winter

Description
Motivation and Emotion – Chapter 3  Eat for 3 basic reasons o Source of energy o Necessary elements for rebuilding cells and manufacturing various chemicals, hormones and enzymes that make it possible for body to perform variety of functions o Need to be able to remove toxins that are often a by-product of eating various foods  Also eat for social or psychological reasons  How do humans avoid toxins? o Biological component  Humans have evolved a number of mechanisms to guard against eating natural toxins  Smell and taste often a source of toxins  Gagging, spitting and vomiting is the second line of defense  Nausea also a protective mechanism  Instead of digesting foods that are toxic, our body rejects it, and simple conditioning teaches us to avoid similar foods  Research to support food sensitivity in pregnant women  Plant toxins that can be tolerated by adults are linked to birth defects and spontaneous abortion  Sickness is at highest when embryo’s organ systems are being laid down and wane when nearing completion  Tend to avoid bitter, pungent, highly flavoured and novel foods  Sense of smell is hypersensitive  Universal across all cultures  Greater pregnancy sickness less likely to bear offspring with birth defects o Learned component  Organisms learn to avoid things that make them sick  Animals are biologically prepared to make certain associations and not others  Potentially toxic foods taken in small amounts might only make us sick, and will not result in death  Highly adaptive behaviour  Will result in learning to avoid these foods in the future  Important that food supply not be too restrictive, equipping brain with ability to potentially avoid toxic foods has potential of doing that  Sampling helps to avoid potentially toxic foods o Cooking foods can take out toxins  Cooking may be cultural conditioning  Food preferences largely learned and mechanism that governs these preferences is taste o Learning to only eat foods caretakers give us  Trying novel foods may take more time to adapt to o Cognitive component  As more toxins are being artificially created, it creates the problem of how to avoid the chemicals that may kills us  Warnings help to deter us from eating toxic foods  Toxins exist in small amounts in foods we eat, which is not harmful  In larger amounts, it builds up in the body  Food selection o Food and energy: fats, carbohydrates and proteins  Stomach and intestines breaks down food into more basic units that can be used for energy  Carbohydrates – starches and sugars  Glucose, fructose, galactose 1 Motivation and Emotion – Chapter 3  Glucose that is not used converts into glycerol, and if body does not have enough carbs in diet, then body will break down the stored glycerol stores  If there is not enough glucose/sugars for body to use, then muscles will start to be digested  Fats  Get from meats, milk products and seeds/grains (ones used to make cooking oils) and broken down into fatty acids  Converted into energy through fatty acid oxidation o Not as efficient as converting glucose into glycerol  Fatty acids not used for immediate energy are stored under the skin in places such as the stomach, hips, thighs and arms  Fat can be made from excessive glucose o This conversion does not allow for immediate access of this fat o Can be a source of long-term energy  Proteins  Meats, beans, nuts and seeds  Broken down into amino acids, which convert into glucose or fat  20 different amino acids o Used for growth, repair and energy  Takes body a couple of hours after a meal to digest and absorb  Intestine act as an energy storehouse for energy during this  Amino acids and sugars go directly into the liver  Liver regulates amino acid levels in the blood o Food and nutrients  Balanced diet involves 50-60% carbohydrates, 10-20% fats, 10-20% proteins o Humans evolved as meat eaters  Distinct advantage to becoming omnivores, means we will not be dependent on one food source  Being an omnivore increases odds of being poisoned  More foods that one eats, greater the likelihood of being poisoned  Evidence that suggests meat /protein is essential to our diet  Extremely difficult for humans to get all the essential nutrients from an exclusively vegetarian diet  Human body cannot produce all the vitamins/nutrients by itself, and meat/protein provides body with the lacking nutrients  Amino acids contained in proteins provide body basic components to manufacture neurotransmitters  Small intestine’s job is to break down and absorb proteins (unique to humans)  Teeth built to eat meat (incisors)  Ancestors ate meat o Biological component  Role of taste in food selection  Two important unlearned taste preferences o Sweet and fatty o Born with preference for sweet foods and fatty foods  Sweet foods tend to be non-toxic and good source of calories  People who restrict carbohydrate diets develop condition called ketosis o Developed when body can no longer supply brain with glucose and forced to burn ketone bodies  During diets, many people lose weight in muscle mass, rather than fat o Learned component 2 Motivation and Emotion – Chapter 3  Eating preferences of different ethnic groups provide evidence that learning plays important role in diet  Food selection comes from learning to avoid all foods that produce some type of aversive state  Modeling parents and developing preferences, eliminate process of trial-and-error learning  Due to availability of food, learning process is flexible  Many of the new preferences linked to taste/texture more than nutritional value  Humans prefer salt  Deprivation of salt produces highly aversive and life-threatening state  Much of the junk food we eat are high in sugar/fat and salt, but low in nutrients o Cognitive component  Our modern society depends on ability to think and reason  Most fast foods and junk foods taste good because they are sweet, fatty or salty, but don’t provide basic nutrients  Ingredients are now listed on foods so people can make conscious efforts to eat foods that are nutritious  Distinguishing between hunger and eating o Important to distinguish between concepts of hunger and eating  Hunger is a biological need o We don’t eat just because we’re hungry, but behaviour also affects it o Satiety is a biological state  We sometimes eat more than we need to  Often eats more than our satiety o Eating as a sensory experience  Not only eat for taste, but because of texture as well  Eat for positive-incentive value of foods  If taste is enhanced, humans eat more, regardless of how hungry  Greater variety – eat more  People tend to eat more when surrounded by other people  Experiment where consumption of liquid diet was in situations with no social interactions o Nonobese individuals kept diet to 2400 calories o Obese individuals droped diet to 500 per day (3000 less than otherwise)  Question of overweight and obesity o Individuals are categorized as obese if they exceed average weight b a given percentage o Within us, there lives potential obese person, ready to emerge if given the opportunity o Insulin levels at the centre of explaining digesting and eating o Failure to produce sufficient insulin – diabetes  Serious disorder that can lead to vascular and retinal damage o Insulin helps glucose from blood enter the cells of the body o Diabetics have difficulty breaking down carbohydrates  Daily injections of insulin and restricted intake of carbohydrates can help with this o Too much insulin can also lead to obesity  Hypoglycemia o When people become overweight, develop condition called hyperinsulinemia  Chronically low blood glucose and constant hunger o Biological component  Genetic factor  Adopted children look more like their biological parents in weight than their adoptive parents 3 Motivation and Emotion – Chapter 3  Identical twins more similar in weight than fraternal twins  Substantial heritability for obesity and binge eating  Energy expenditure  Three components o Basal metabolic rate (BMR)  Amount of energy we use in given period relative to body size o Physical activity o Specific dynamic action  Increase in energy expenditure following the ingestion of food  Actual proportions of energy expended in exercise and metabolism depend on individual exercise patterns  Obesity and anorexia as malfunctions of the hypothalamus  Hypothalamus involved in variety of motivational functions, includes hunger and eating  Two areas linked to eating o Lesions of ventromedial nuclei (VMN)  Produce over eating, obesity  Showed these characteristics  Unresponsive to normal satiety cues  Will not work as hard to obtain food  Stop eating adulterated foods before animals without lesion  Eat large amounts of palatable foods o Lesions of lateral hypothalamus  Failure to eat, anorexia  Lesions of the ventromedial nuclei o Obese people characterized with chronic hyperinsulinemia o Satiety linked with high levels of leptin in the VMN  Lesions destroy leptin receptors  Obese people have high levels of leptin in brain o People born with different rates of metabolism  Lesions of the lateral hypothalamus o Shown to produce effects of eating cessations o Body loses weight o Degree of anorexia displayed related to size of the lesion  Set point theory  Proposed set-point theory of weight level o Hypothalamus sets our weight  People with high points are inclined to be overweight o Feel hungry and to satisfy their hunger, would be inclined to overeat  Weight would match set point, and food consumption would level off  Positive-incentive theory  When exposed to environment that allows for unlimited access to food, they are inclined to become overweight  Tend to eat more when food tastes good, even when th
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