The document describes physiological factors that influence hunger and satiety. It discusses how food is digested and the role of lactase in digesting dairy. It notes that many adults can digest dairy while most Southeast Asians cannot due to genetic differences. Short and long-term regulation of hunger is explained, including the role of the stomach, intestines, leptin, and hypothalamus in signaling fullness to the brain. Eating disorders like bulimia nervosa and anorexia nervosa can occur when these homeostatic mechanisms fail.

1. Chapter 9.3:
Hunger
Prepared by: Kimberly B. Magadia

2. Learning Outcome
o Described the physiological factors that
influence hunger and satiety.

4. Digestion
and
Food Selection

5. How do we processed food?
Mouth
Esophagus
Stomach
Small intestine
Large intestine

6. Consumption
of
Dairy Products

7. o Newborn mammals survived at first on
mother’s milk and most of them about the
age of weaning lose the intestinal enzyme
lactase.
o Lactase – necessary for metabolizing
lactose or sugar in milk.

8. o Many adults have enough lactase levels to
consume milk and other dairy products.
However, the prevalence of the necessary
genes varies.
o Most Southeast Asian adults lack the genes
that help digest lactose, the main sugar in
milk.

9. Food Selection
and
Behavior

10. Fact or Bluff

11. Eating sugar makes
children hyperactive.

13. Eating turkey causes
sleepiness.

15. Fish is a brain food.

17. Short- and
Long- Term Regulation
(Physiological Factors that
InfluenceHunger and Satiety)

18. Oral Factors
f
o People cannot become satiated
without tasting their food.
o Taste contributes to satiety.

19. The Stomach and Intestine
oThe main signal to end meal is distension of
the stomach.
oVagus nerve conveys info to the brain about
the stretching of the stomach walls.
oDuodenum – part of small intestine. Its
distention releases hormone cholecystokinin
(CCK) which produces satiety.

20. Leptin
o Leptin is a hormone that signals your brain
about your fat reserve.
o The more fat cells, the more leptin.
o If you release more leptin, you tend to eat
less and be more active.
o If you lacked leptin, you tend to eat more
and be less active.

21. Brain Mechanisms

22. The Arcuate Nucleus and Paraventricular
Hypothalamus
o Hormones that increases satiety.
-insulin, CCK and Leptin
o Hormones that increases hunger
-Ghrelin

23. Lateral Hypothalamus and Medial
Hypothalamus

24. Lateral Hypothalamus Medial Hypothalamus
(Ventromedial
Hypothalamus)
known as: Star-eating Center Stop-eating Center
Function Controls insulin
secretion and alter
tastes responsiveness.
Central area that
inhibits feeding.
Damage in this area
leads to:
Under-eating or
refusal of food and
water.
Overeating and
weight gain.

25. Eating Disorder

26. Eating disorders occur when our homeostatic
mechanisms fail.
Bulimia Nervosa
o is a condition in which people alternate between
binges of overeating and periods of strict dieting.
Anorexia nervosa
o refusal to eat enough to maintain healthy body weight.

27. Thanks!