Ingestive behaviours
The need for food:
● Fuel-energy
● Nutrition-chemicals and nutrients,vitamins
What are the factors that affect out eating habits
Biological:
Genetics
Economic-availability and cost
Social: cultural,religiou,pressures
Psychological factors: food preferences,comfort eating
Associative learning-reduced stress and increased pleasure-self medication
Physiological regulatory mechanisms:
Regulated by negative feedback
Correctional mechanisms-replenish body depleted stores of water/nutrients
Detectors- initiate Correctional mechanisms
Satiety mechanisms-monitor the activity of the correctional mechanisms and will inhibit
further actions= maintains internal environment at its optimal state
These are needed as there is a delay between ingestion and replenishment
Eg control of drinking:
Thirst:
Triggers of thirst:
Increase in plasma osmolariy, angiotensin 2 and relaxin via subforminal organ and organum
vasculosum of the lamina terminalis
Modulated by GI afferent and baroreceptor inputs
Median preoptic nucleus-signals to insula and cingulate cortex
CNS and hunger-hypothalamus-key controller
, 2 regions-influence feeding behaviour
Lateral hypothalamus- hunger centre
Damage=anorexia
Ventromedial hypothalamus-satiety centre
Damage=obesity-won’t stop eating
Feedback mechanisms-control food intake:
Inhibition of food intake
Stretch receptors-inhibit food intake
Activate sensory afferent pathways in the vagus nerve
Peptide yy- released by SI after meal-proportional to calories ingested
CCK- related to the number of nutrients,provides a satiety signal to the brain
Insulin- detection of insulin levels-absorptive phase of metabolism
Leptin- produced in increasing amounts of fat cells- increase in size-inhibits food intake
Promotion of food intake:
Hypoglycemia
Ghrelin- binds to receptors in the hypothalamus-stimualtes
High levels-with fasting
Blocking ghrelin-weight loss
Increasing ghrelin-weight gain
5 modalities of taste
Sweet-sugars,alcohols,esters
Sour-H+
Salty-ionsied salts
Ummai-L- glummate
Bitter- nitrogen and alkaloids
Modulation of taste:
Angiotensin 2-decreases sensitviity to salty increases to sweet
Glucagon-increases sensitity to sweet
TNF alpha-decrease sensitivity to bitter tating
Pica-craving to non-foods
Association with micronutrient deficiencies
Sodium appetite:
Increased palatability and drive to ingest salty substances
The need for food:
● Fuel-energy
● Nutrition-chemicals and nutrients,vitamins
What are the factors that affect out eating habits
Biological:
Genetics
Economic-availability and cost
Social: cultural,religiou,pressures
Psychological factors: food preferences,comfort eating
Associative learning-reduced stress and increased pleasure-self medication
Physiological regulatory mechanisms:
Regulated by negative feedback
Correctional mechanisms-replenish body depleted stores of water/nutrients
Detectors- initiate Correctional mechanisms
Satiety mechanisms-monitor the activity of the correctional mechanisms and will inhibit
further actions= maintains internal environment at its optimal state
These are needed as there is a delay between ingestion and replenishment
Eg control of drinking:
Thirst:
Triggers of thirst:
Increase in plasma osmolariy, angiotensin 2 and relaxin via subforminal organ and organum
vasculosum of the lamina terminalis
Modulated by GI afferent and baroreceptor inputs
Median preoptic nucleus-signals to insula and cingulate cortex
CNS and hunger-hypothalamus-key controller
, 2 regions-influence feeding behaviour
Lateral hypothalamus- hunger centre
Damage=anorexia
Ventromedial hypothalamus-satiety centre
Damage=obesity-won’t stop eating
Feedback mechanisms-control food intake:
Inhibition of food intake
Stretch receptors-inhibit food intake
Activate sensory afferent pathways in the vagus nerve
Peptide yy- released by SI after meal-proportional to calories ingested
CCK- related to the number of nutrients,provides a satiety signal to the brain
Insulin- detection of insulin levels-absorptive phase of metabolism
Leptin- produced in increasing amounts of fat cells- increase in size-inhibits food intake
Promotion of food intake:
Hypoglycemia
Ghrelin- binds to receptors in the hypothalamus-stimualtes
High levels-with fasting
Blocking ghrelin-weight loss
Increasing ghrelin-weight gain
5 modalities of taste
Sweet-sugars,alcohols,esters
Sour-H+
Salty-ionsied salts
Ummai-L- glummate
Bitter- nitrogen and alkaloids
Modulation of taste:
Angiotensin 2-decreases sensitviity to salty increases to sweet
Glucagon-increases sensitity to sweet
TNF alpha-decrease sensitivity to bitter tating
Pica-craving to non-foods
Association with micronutrient deficiencies
Sodium appetite:
Increased palatability and drive to ingest salty substances
