hunger, eating and health Flashcards
mouth and salivary glands
mastication/chewing and saliva (alkaline)
oesophagus
- transporting food to stomach
- set up for alkaline conditions as stomach is acidic
stomach
- churning food and breaking it down
- acid digestive enzymes
liver/gall bladder
-additional enzymes added to small intestine
pancreas
-produces insulin and glucagon to store and release energy
small intestine
-absorbs nutrients
large intestine
-removes water and packs waste
rectum/anus and bladder
store and expels waste
pancreatic hormones
- insulin: shifts carbs from blood–>storage (glycogen, proteins)
- glucagon: shifts fuel from storage to where it is needed (glycogen–>proteins, carbs, frees fat stores to use as fuel when glucose low)
why is our intake so complex?
- we are omnivorous
- diet includes range of key elements that our bodies have evolved to process
- lots of variation between species e.g. number of stomachs
- some variation within species e.g. dairy/gluten tolerance
what is the outcome of digestion?
- lipids/fats–>fats - largest + most efficient energy store
- amino acids–>proteins - mostly in form of muscle tissue
- glucose–>glycogen - stored in muscles and liver, fast release
- minerals + vitamins–>body structure e.g. bones, cell structure
how do we ensure these outcomes of digestion occur?
- homeostasis/set point theory - when we’re running low on food we experience: hunger and craving
- brain sensitive to shortage of glucose (hypothalamic regulatory nuclei)
- liver sensitive to shortages of glucose + lipids
- stomach sends signals to brain via release of ghrelin
why does eating go wrong sometimes?
- internal factors e.g. learning, emotions
- environmental factors e.g. toxic environments
homeostasis
when running low on fuel
-hunger (motivational state) due to low levels of fatty acids+glucose
-craving (automatic behavioural state)
body corrects by releasing glucose + taking in more food
why do we feel full/satiety?
short term satiety signals: adequate glucose + lipid levels detected in brain + liver
- stomach distension- swollen
- buccal activity - lots of chewing
- high levels of sensory stimulation - big on taste + smell
- appetite suppressant chemicals e.g. caffeine, amphetamines
- diet products try to offset adequate levels with these factors
what does research say about the brain and satiety?
- some research says hypothalamus is centre for satiety
- recent evidence suggests there isn’t such
- looks like it is hormonally controlled: ghrelin, neuropeptide Y, serotonin
what hormone do fat tissues secrete? function?
leptin
- increases body metabolic rate
- decreases food intake by desensitising brain to hunger signals + inhibiting the effect of other hormones that drive eating
what is the satiety cascade?
sensory(beliefs)–>cognitive–>post-ingestive(stomach+intestines)–>post-absoptive(liver+metabolites)
health implications from poor eating:
nutritional deficits: scurvy, rickets, Korsakoff’s syndrome
starvation effects either immediate, long-term or both:
-concentration
-socially withdrawn
-physical + mental development stunted
-emotional instability
-all physical systems
starvation effects can pass to generations
-obesity in child of starved mothers
obesity
- affects multiple systems e.g. social functioning
- strong link to premature mortality
- related to specific problems in children e.g. bullying
what are the factors that oppose homeostasis?
- genetics
- learning
- social learning
- social pressures
- food industry
- ‘toxic environment’
genetic/evolutionary factor
- genetic factors make us more likely to eat certain foods
- predisposed to high energy, high-taste foods
- less likely to enjoy bitter
learning factor
-learned taste preferences and aversions influenced by culture, upbringing, satiety to specific foods(e.g. eat a varied diet)
social learning factor
- we eat in a number of ways that match people around us
- imitation of how/amount/speed
- cultural influence
