COGS101 Lecture Notes - Leptin, Hard Wired, Dieting
23 May 2018
School
Department
Course
Professor
Week Three Lecture – Appetite and
Learning
Appetite
Eating has a big impact on health:
- By 2025, 1 in 3 Australians will be obese
- Cancer and heart disease has been linked to a poor diet
- Eating disorders are costly and hard to treat – anorexia being the deadliest
psychiatric condition
- Diet-related illnesses costs the health system around 60 billion per year
How do we control food intake?
BODY:
- Energy Levels:
o Short term store glucose – less important for intake
o Long term store using fat – more important for intake
o Fat cells secrete a hormone called leptin
o More fat = more leptin (suppresses appetite)
o Less fat = less leptin (increases food intake)
- Sensation:
o Food flavours – hard wired to like sweet, salty and fatty things
o Flavours are associated with appearance and smell
o When we see/smell food we like, we want to eat it
o The more you eat a specific food, the like for it will decrease (acts to signal
the end of a meal, telling you that you are full)
- Digestive Organs:
o Multiple organs involved with this, signals are sent to the brain about the
status of food digestion
o Signals: stomach is distended or empty, gut and stomach tastes receptors
o How are the signals communicated?
▪ Nerves
▪ Hormones
▪ Nutrients
BRAIN:
- Neurochemicals:
o Serotonin and Dopamine modulate eating – they increase and decrease
appetite.
▪ They are part of appetite suppressants, they are either SE or DA
agonists (binding to the receptors)
▪ They are neurotransmitters, so they affect body weight.
o Neurochemicals are modulated by events in the body:
find more resources at oneclass.com
find more resources at oneclass.com
▪ Leptin (from fat cells) stimulates release of CRH in the brain
(corticotrophin releasing hormone) supressing appetite.
▪ Ghrenlin (from stomach) stimulates release of NY (neuropeptide Y) in
the brain to increase appetite.
- Locations:
o Hypothalamus
▪ Ventromedical nucleus (stop eating)
▪ Lateral hypothalamus (start eating)
▪ CRH and BY exert effects here
o Cortical
▪ Frontal (impulsivity)
▪ Insula (interoception)
o Limbic system
▪ Hippocampus (memory) – Eating and Henry Molaison
ENVIRONMENT:
- Food:
o Showing you food will make it more likely to eat food – triggers a cephalic
phase response (salivation, insulin release etc.)
o Few social prohibitions on eating, anywhere and anytime – snack machines,
coffee shops, supermarkets etc
o Food advertising – US 4.2 Billion spent per year
- Time and Place:
o People are habit bound – eat at the same time (sometimes place) each day
o Time will be associate with eating – can be seen when travelling time zones,
you will get hungry at inappropriate times
o In deep caves eating behaviour changes significantly because people do’t
know what time it is
- People and Leisure:
o The number of people we eat with affects how much we eat
o Having a large plate will make you eat more
o Average portion sizes have increased
o We are mainly driven by environmental factors when it comes to eating
o There is not much of a conscious control of how much we eat
o Biological factors only important at extremes (starvation or gross over-
indulgence)
Obesity
BREAKDOWN:
- Main eating related health problem
- Causes chronic illness – type II diabetes, circulatory disease, joint damage, cancer
(and more)
- Costly from a personal, social and economic perspective
- Obesity is determined by BMI
- People in the West have been getting fatter over the last 50 years.
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
By 2025, 1 in 3 australians will be obese. Cancer and heart disease has been linked to a poor diet. Eating disorders are costly and hard to treat anorexia being the deadliest psychiatric condition. Diet-related illnesses costs the health system around 60 billion per year. Locations: hypothalamus, ventromedical nucleus (stop eating, lateral hypothalamus (start eating, crh and by exert effects here, cortical, frontal (impulsivity) Insula (interoception: limbic system, hippocampus (memory) eating and henry molaison. In deep caves eating behaviour changes significantly because people do(cid:374)"t know what time it is. Causes chronic illness type ii diabetes, circulatory disease, joint damage, cancer (and more) Costly from a personal, social and economic perspective. People in the west have been getting fatter over the last 50 years. Environment has changed eat more and move less. Genes are a good predictor twin studies show that 70% of variability in weight can be accounted for by shared genes.
