Module 37 - Hunger

Question 1

What triggers feelings of hunger?

Answer 1

• Hunger pangs from stomach
• Contractions of the stomach match feeling hunger
• Hunger still experienced with stomach removed or by-passed
• Chemical signals at play

Question 2

Body Chemistry and Brain

Answer 2

When the brain watches chemical signals from body to regulate energy balance

Question 3

Blood Glucose Levels

Answer 3

Neurons in hypothalamus sense blood sugar changes

1. if low, triggers hungers
2. if high, signals fullness

Question 4

Insulin

Answer 4

Comes from pancreas, lowers blood sugar (decreases hunger when injected into brain)

Question 5

Ghrelin

Answer 5

Released by stomach when empty

• stimulates hypothalamus
• potent hunger enhancing effects

Question 6

Obestatin

Answer 6

Released from stomach when full

- reduces hunger

Question 7

Peptide YY (PYY)

Answer 7

Released from digestive track when full (reduces hunger as well)

Question 8

Leptin

Answer 8

Released from fat cells (reduces hunger)

- increases metabolism to burn fat

Question 9

Hypothalamus

Answer 9

2 regions important for hunger

1. Lateral Hypothalamus
2. Ventromedial Hypothalamus

Question 10

Lateral Hypothalamus

Answer 10

• increases hunger when stimulated

- releases Orexin

Question 11

Ventromedial Hypothalamus

Answer 11

• decreases hunger

- stimulation reduces food intake

Question 12

Set Point

Answer 12

Level of body weight that the body maintains

• happens when complex interactions of chemical factors and brain
• if body weight falls below set point (food deprivation) hunger signals increase and food intake is reduced
• if body is over fed, hunger decreases and food intake is reduced

Question 13

Metabolic Compensation

Answer 13

When thyroid hormones decrease, the body also can lower basal metabolic rate when food is scarce to conserve energy

Question 14

Psychological factors (non-homeostatic)

Answer 14

• memory of last meal (awareness)
• taste (novelty, sensory specific satiety)
• boredom (adjunctive behaviour)
• stress and mood levels
• body image (later)

Question 15

Social/Cultural Factors

Answer 15

• culturally learned taste preferences
• presence of others
• societal trends, body image standards

Question 16

Eating Disorders

Answer 16

Most Common

1. Anorexia Nervosa
2. Bulimia Nervosa
3. Binge-eating disorder

Question 17

Anorexia Nervosa

Answer 17

• starts with diet
• female teens (3 in 4 cases)
• last 1-2 years
• fear of gaining weight, diet continues
• lok at themselves as over weight

Question 18

Bulimia Nervosa

Answer 18

• begins with diet
• a person breaks diet and binges (over eats) then feels guilty and the purges (vomits/laxatives), fast or exercise vigorously
• cycle continues
• experiences depressions (sometimes)

Question 19

Binge-Eating Disorder

Answer 19

• similar to bulimia

- binge eat but no purge or exercise vigorously

Question 20

Statistics

Answer 20

Anorexia Nervosa 0.6% population
Bulimia nervosa 1%
Binge-eating disorder 2.8%

Question 21

Obesity and Weight Control - Psychological Effect

Answer 21

• low self esteem

- 28% increase in depression and anxiety disordes

Question 22

Social Effect

Answer 22

• viewed as less sincere, less friendly, more obnoxious (studies)
• job discrimination: hiring and salary ($7000)
• less likely to be married

Question 23

Why do we have fat?

Answer 23

• stored energy for lean times

Question 24

Why so hard to lose weight?

Answer 24

1. fat cells

2. set point and metabolism

Question 25

Fat Cells

Answer 25

- you can make fat cells but you can't get rid of them - existing cells grow and divide - they can only shrink after that

Question 26

Set Point and Metabolism

Answer 26

- fat cells have lower metabolism rate than other cells - lower metabolism requires less energy to stay the same - people with more fat need to lessen calories per pound to lose same % as less fat people - when you start to diet, your body loses weight initially, but senses in energy drops below its set point - lowers metabolic rate to defend weight - net result is levelling off of weight