Session 5

• Biological Basis of Motivation II
• MOTIVATION & EMOTION | PSY5105
• Haqeeqa Munas
• Lecture Contents


  • Motivation of Hunger and Eating
  • Motivation of Thirst and Drinking
  • Sexual Motivation
  • Aggression Motivation
• Hunger


  The motivation for us to be able to know that we need to get the nutrients into our bodies
• Eating


  A behaviour which involves the consumption of food
• Eating


  1. Food ingestion

  2. Absorption - Food energy is extracted and stored as either glycogen or fat

  3. Fasting - Energy stores are converted to glucose for use by the body

  
• Regulation of Food Intake

  • Monitor and detect internal food need
  • Initiate and organise eating behaviour
  • Monitor quantity and quality of food eaten
  • Detect when sufficient food has been eaten and stop eating
• Factors that Affect Hunger


  • Physiological
  • Social and Environmental
  • Cognitive
• Hormonal Control of Hunger

  • Ghrelin hormone activates hunger
  • Leptin hormone decreases hunger

  
• Short-Term Appetite Model

  1. When blood glucose level is low, liver gives out excitatory signals, lateral hypothalamus stimulated by ghrelin hormone, increased hunger

  2. When blood glucose level is high, bloated stomach, release of CCK, liver stimulation, ventromedial hypothalamus stimulated by Leptin hormone, decreased hunger

  
• Long-Term Energy Balance Model

  1. Gastrointestine secretes ghrelin hormone, promotes weight gain motivation, increased food intake

  2. Adipose tissue secretes leptin hormone, promotes weight loss motivation, reduce food intake

  
• Hunger actually comes from the brain
• Lateral Hypothalamus (LH)


  Plays role in switching 'on' eating behaviour
• Ventromedial Hypothalamus (VMH)


  Plays role in switching 'off' eating

  
• Mice with damage to the ventromedial hypothalamus can become obese
• Leptin


  A protein produced by bloated fat cells that signals the hypothalamus to curb eating and increase activity

  
• Set Point


  Hypothalamus acts like a thermostat to maintain a certain weight range
• Environmental & Social Factors that Affect Hunger & Eating

  • Food Palatability
  • Food Variety
  • Time of Day
  • Presence of Others
  • Memory of Last Meal
  • Smell & Texture
  • Colours
  • Nutritional Value
• Cognitive Basis of Hunger

  Successful dieting involves reducing responsiveness to internal cues and substituting conscious cognitive controls for unconscious physiological ones

  
• Satiety


  Mechanisms at the brain level (ventromedial hypothalamus) and gastrointestinal tract level (stomach) that control when we stop eating

  
• Obesity


  Body weight of 20-25% or more in excess of desirable body weight
• Consequences of Obesity


  • Physiological: Heart Disease, Diabetes, Stroke, Early Mortality
  • Psychological: Negative Stereotypes, Discrimination, Difficulty in Relationships, Low Self-esteem
• Set Point Theory


  We have a predetermined weight set by the hypothalamus that the body attempts to maintain
• Internal-External Theory


  Obese people respond more to external cues of hunger (e.g. time) than internal cues
• Boundary Theory


  There are biologically determined boundaries of hunger and satiety, but the space between them is determined cognitively
• Eating Disorders


  • Binge Eating
  • Anorexia Nervosa
  • Bulimia Nervosa
• Anorexia Nervosa involves an intense fear of becoming fat that leads to self-starvation and weight loss accompanied by a strong belief that one is fat despite objective evidence to the contrary
• Bulimia Nervosa is an eating disorder in which a victim alternatively consumes large amounts of food (gorging) and then empties the stomach (purging), usually by induced vomiting and/or use of laxatives

  
• Body Mass Index (BMI) is a numerical index calculated from a person's height and weight that provides a measure of body size
• Eating disorders


  Disorders where people are normal or above weight
• Studies show there is more Anorexia in westernized cultures than other cultures, because the social value of slimness pushes people to be thinner
• Cognitive factors in Anorexia

  Distorted body image, dissatisfaction with own body image influenced by cultural value of slimness
• Cognitive factors in Bulimia


  Motivated to escape from reality by binging, cultural learning that one needs to be thin to be accepted
• Body Mass Index (BMI)


  Numerical index calculated from a person's height and weight that is used to indicate health status and disease risk
• Genetic factors play a key role in determining a person's weight
• Basal Metabolic Rate (BMR)


  The minimum energy needed to keep an awake, resting body alive
• Body image


  How an individual sees their own body and how attractive they feel themselves to be
• Role of media in influencing body image and eating disorders
• Thirst


  A drive, a basic compelling urge that motivates action, arises from a lack of fluids or an increase in the concentration of certain osmotic solutes