Seminar 3: Food addiction / intake Flashcards
What are the 3 steps to the HPA axis?
- hypothalamus releases CRH
- anterior pituitary releases ACTH
- adrenal cortex releases cortisol
How does your stress response influence the HPA-axis?
- manageable stress = smaller HPA response and quicker to baseline
- overwhelming stress = higher HPA response and longer back to baseline
What are the two main processes involved in eating?
- Hunger - to eat
- Satiety - to stop eating
What is the set-point-theory-of-hunger? Theory of food intake
body uses regulatory mechanisms to keep the weight in check
every person has a predisposed weight range that we maintain on average for optional functioning
weight = stored energy in case we require it
What happens when we eat too much / too little?
- our metabolic rate increases a bit to help burn off the excess of what we have consumed
- if we eat less, our metabolic rate slows to keep energy in our system for a bit longer
What is positive incentive theory?
people are driven to eat based on the anticipatory or reward intake of food
In positive incentive theory, what happens when food as a need becomes a want?
As a behaviour, food becomes a reward for positive behaviour or on rare occasions, forming an association between ‘treats’ and ‘behaviour’
Biological results in dopamine release, causes behavior and biological conditioning where stimulus is paired with dopamine and treats
“You see and want food, you enjoy food, cycle repeats”
Whats the outcome for behavioural and biological conditioning in positive incentive theory?
This desire for food intake can be caused in the absence of hunger, eg. desire for food without being hungry when seeing food, because dopamine has been released as the brain has associated the food with reward
What is stress (affect) regulation theory?
that food intake promotes stress or emotional relief
- stress increases HPA axis
- stress chemicals make people seek out comfort foods such as sugars/fats
- biologically, sugars/fats can dampen cortisol activity, and thus reducing stress
- becomes a learned response and repeats
What does the arcuate nucleus do?
- regulates feeding and metabolism, receptor site for NPY and ghrelin
What does the paraventricular hypothalamus do?
inhibitory control of food intake, receptor site for leptin and HPA axis
What does the laternal hypothalamus do?
responsible for reward related or motivated food intake - responses to highly palatable stimuli
receptor site for dopamine
What is the ventromedial nucleus?
- responsible for satiety and controlling fullness
What are the 3 endocrine hormones for hunger?
- Ghrelin - orexigenic hormone stimulates hunger by causing stomach contractions, sine wave activity, eat and ghrelin drops
- leptin - anorexigenic - appetite suppressant, encourages adipogenesis, opposite of ghrelin, leptin levels increases as you eat food
- dopamine - has central and peripheral pathways that dont crossover due to BBB
- in CNS, dopamine = reward eating,
- in PNS, dopamine = glucose, stress response and emotional eating for relief
What is leptin resistance?
chronically elevated leptin levels result in desensitization to leptin and feelings of satiety, can’t tell when full and often gain weight, thought to be underlying to obsesity