GUT- Control of Food Intake Flashcards
define hunger
discomfort caused by lack of food and the desire to eat - a strong physiological craving / drive for food / sensation of emptiness in the stomach
define satiety
state of being full after eating food (no longer need to continue eating)
define aphagia
inability to refusal to swallow
define hyperphagia / polyphagia
abnormal desire for food (unsatisfied extreme drive to eat)
what factors influence appetite
family gatherings, food palatability, emotional, habitual, circadian factors
what controls food intake
hypothalamic control - young people can maintain constant body weight - ability to do so decreases with age
how does stimulation and lesion of ventromedial nuclei affect food intake
stimulation - aphagia (swallowing difficulty)
lesions - hyperphagia (increased appetite or excessive hunger)
how does stimulation and lesion of lateral hypothalamus affect food intake
stimulation - increase feeding
lesion - aphagia
what is the role of orexigenic neurotransmitters
increases appetite
what is the role of anorexigenic neurotransmitters
decrease appetite
which feeding behaviour is modulated by the lateral hypothalamus
hunger / thirst
which feeding behaviour is modulated by ventromedial nucleus
satiety centre
which feeding behaviour is modulated by dorsomedial nucleus
modulates energy intake
which feeding behaviour is modulated by paraventricular nucleus
modulated feeding behaviour - increase / decrease feeding
what effect does leptin have on food intake
decrease
which feeding behaviour is modulated by arcuate nucleus
neurons produce orexigenic signals - increase feeding
which feeding behaviour is modulated by suprachiasmatic nucleus
human body clock located here - circadian rhythm - mood / drive to eat
which feeding behaviour is modulated by medial amygdaloid nucleus
regulation of food intake (by binding of ligands)
what is the role of the prefrontal cortex in control of food intake
influences food seeking behaviour
integrates sensory information from inside and outside the body
recieves emotional and cognitive information from the limbic system
helps one make choices by translating all of the homeostatic and environmental information into a behavioural response
what is the role of the limbic system in modulating food intake
nerve network which is concerned with instinct, learning, reproductive behaviour, emotions / mood (pleasure, fear)
act of satiation of feeding behaviour associated with moto planning and execution
which factors affect if food is sought and what type we ingest
food preferences emotions environment (cold environments stimulate feeding whilst hot environments reduce appetite lifestyle circadian rhythms individual based requirements
what signals appetite
glucose concentration in the blood - stimulates glucose receptors in the hypothalamus
a decrease in blood sugar signals hunger
an increase in blood glucose signals satiety
what is the role of gut hormones in signalling appetite
fat ingestion causes CCK release and the slowing of gastric emptying - sense of fullness
CCK and somatostatin are satiety factors - inhibit further food intake
what type of cells secrete leptin
fat cells
what is the mechanism of action of leptin
acts on the hypothalamus and changes food intake
increases the expression of anorexigenic factors (POMC, CART, CRH)
inhibits neuropeptide Y which stimulates feeding
what effect is seen in humans with leptin deficiency / leptin receptor defects
hyperphagia and severe obesity
what is ghrelin
appetite inducing hormone
what is the mechanism of action of ghrelin
increases central orexins (NPY, AgRP)
circulating levels of ghrelin are high pre-prandially and low post-prandially
what inhibits the secretion of ghrelin
leptin
where is obestatin produced
epithelial cells of the stomach
what is the function of obestatin
opposes the effect of ghrelin
supresses food intake
antagonises ghrelin induced food intake
obstatin mediates its effects via different receptors to ghrelin
what physiological factors give rise to early satiety
reduced capacity to eat
a small meal = state of satiety
gastroparesis (reduced gastric emptying)
cancer
reflux
peptic ulcers
vagotomy impairs accomodation and empyting - a cause of early satiety in some patients
