apetite regulation Flashcards
define appetite, hunger, anorexia, satiety and BMI equation.
Appetite - desire to eat food
Hunger - need of eating
Anorexia - lack of appetite
Satiety- feeling of fullness -
disappearance of appetite after a meal
Body mass index (BMI) - wt (kg)/ht (m2)
outline the different BMI classifications
<18.5 - underweight
18.5 - 24.9 - normal
25.0 - 29.9 - overweight
30.0 - 39.9 - obese
>40 - morbidly obese
outline some risks of obesity.
- Type II diabetes
- Hypertension
- Coronary artery disease
- Stroke
- Osteoarthritis
- Obstructive sleep apnoea
- Carcinoma
name the carcinomas which are caused by obesity
Breast
Endometrium
Prostate
Colon
Why do we eat? - The Satiety Cascade
Internal physiological drive to eat:
Feeling that prompts thought of food and motivates food consumption
External psychological drive to eat:
Sometimes even in the absence of hunger (e.g buffet)
whats the role of the hypothalamus in apetite regulation?
lateral hypothalamus - hunger centre
ventromedial hypothalamic nucleus - satiety centre
leptin
Switches off appetite and is
immunostimulatory
peptide YY
- 36 amino acids
- Structurally similar to NPY
- Binds NPY receptors
- Secreted by neuroendocrine cells in ileum, pancreas and colon
in response to food - Inhibits gastric motility
- Reduces appetite
cholecystokinin
1973 - administration - reduced feeding in rodents
Receptors in pyloric sphincter
- delays gastric emptying
- gall bladder contraction
- insulin release
and via vagus - satiety
ghrelin
- espressed in stomach
- stimulates growth hormone release and appetite
- blood levels high when fasting and fall again upon re-feeding
summary for peripheral appetite regulation
- olfactory, guastatory, cognitive, visual stimuli stimulate apetite
- oral receptors meter food intake and supress feedinh - alter food pleasantness
- ghrelin secretion stimulates food intake
- stretch recpetors in stomach increase satiety
- release of CCK, GLP, insulin, PYY increase satiety to stop feeding
- in the long term leptin, nutrients and temperature regulate satiety and hance energy balance
what regulates satiety?
- leptin
- nutrients
- temperature
outline briefly the factors which control apetite.
- hypothalamus - hunger and satiety centre
- ghrelin - causes hunger
- leptin - inhibits hunger
- insulin - has appetite regulating functions
- peptide YY - reduces appetite
- neuropeptides Y - apetite stimulator
- neurostimulatiors CART and POMC supress appetite
- psychological factors eg stress
- external cues eg sight and smell
Mechanisms that maintain being overweight
- Physical/physiological - more weight = more difficult to exercise (arthritis, stress incontinence) and dieting -> metabolic response
- Psychological - low self-esteem and guilt, comfort eating
- Socioeconomic - reduced opportunities employment, relationships, social mobility
Obesogenic environment
- Physical: TV remotes, lifts, car culture
- Economic: Cheap TV, expensive fruit and veg
- Sociocultural environment: Safety fears, family eating patterns
