Download Module 38 notes - Bremerton School District

Unit VIII:
Motivation & Emotion
Module 38
Hunger Motivation
Hunger: Physiological Factors
38-1
The Physiology of Hunger
38-1
• Stomach contractions (pangs) send
signals to the brain making us aware
of our hunger.
• But, research has shown that hunger
persists without stomach pangs:
Tsang (1938) removed rat stomachs, connected the
esophagus to the small intestines, and the rats still
felt hungry (and ate food).
Body Chemistry & the Brain
• Levels of glucose in the
blood are monitored by
receptors (neurons) in the
stomach, liver, and
intestines.
• They send signals to the
hypothalamus in the brain.
38-1
Hypothalamic Centers
38-1
The lateral hypothalamus (LH) brings on hunger.
Destroy the LH, and the animal has no interest
in eating.
The ventromedial
hypothalamus (VMH)
depresses hunger (makes you
feel full).
Destroy the VMH, and the
animal eats excessively.
Hunger: Psychological Factors
38-2
The Psychology of Hunger
• Memory plays an important role in hunger.
• Due to difficulties with retention, amnesia
patients eat frequently if given.
• This suggests that part of knowing
when to eat is our memory of our
last meal.
38-2
Taste Preference: Biology &
Culture
38-2
Body chemistry and environmental factors
influence not only when we feel hunger but what
we feel hungry for!
Whale blubber!
Roasted guinea pig!
Situational Influences on
Eating
We eat more when
eating with others.
38-2
When given a
large serving
utensils or a
large
bowl/plate, we
take more food.
When offered a
supersized portion,
we put away more
calories.
Obesity & Weight Control
38-3
Obesity
38-3
• Obesity is a disorder characterized by being
excessively overweight.
• Obesity increases the risk for health issues like
cardiovascular diseases, diabetes, hypertension,
arthritis, and back problems.
Obesity Rates Around the
World, 2010
The Genetic Factor
38-3
Studies reveal that body weight has a genetic basis
• Identical twins have closely similar weights, even
when reared apart.
• Given an obese parent, boys are 3x more likely,
and girls 6x more likely to be obese than those
with normal-weight parents.
• Adoptive siblings’ body weights are uncorrelated;
people’s weights resemble those of their biological
parents and siblings.
Activity Levels
38-3
• Lack of exercise is a major contributor to obesity.
• Just watching TV for two hours resulted in a
23% increase of weight when other factors were
controlled.
Food Consumption
38-3
Over the past 40 years, average weight gain has
increased. Health professionals are pleading with US
citizens to limit their food intake.