eating regulation Flashcards
What regulates eating?
energy deficit
nutrient deficits
pleasure seeking
How is energy homeostasis achieved?
Energy balance = Intake – Expenditure
Caloric intake = metabolic rate, thermogenesis, activity
what are the parameters of regulation?
Quantity (E Intake): meal-size and frequency
Quality = Composition of Meal: food selection
recruits motivational, reward, learning, memory and cognitive systems
Energy Output: physical activity and activity of sympathetic NS
recruits systems controlling thermogenesis, basal metabolism and movement
Energy Storage: body weight and composition
recruits endocrine/hormonal and neural systems
eating can also be voluntary
What is short term control?
regulates meal size and frequency
dynamic parameters (minutes, hrs) positive and negative feedback from the ingested meal/ GI tract = “hunger and satiety signals
What is long term control?
defends BW / adiposity
proportional to total body fat
“adiposity signals”: insulin, leptin
What are the three phases of short term regulation of feeding behavior?
Cephalic
Gastric
Substrate
What is the cephalic phase of short term regulation of feeding and what hormones are released?
Cephalic - hunger
Ghrelin released when stomach is empty
Activates NPY- and AgRP-containing neurons in arcuate nucleus
What is the Gastric phase of short term regulation of feeding and what hormones are released?
Gastric - feeling full
Gastric distension signals brain via vagus
Works synergistically with CCK released in intestines in response to certain nutrients
Insulin also released by β cells of the pancreas - important in anabolism
What is substrate phase?
the time after a meal is eaten until the hunger feeling
When is the blood insulin levels the highest?
during substrate phase
What is prandial and post absorptive state?
Prandial state - Anabolism: Energy storage as glycogen and triglycerides
Postabsorptive state - Catabolism: Breaking down complex macromolecules
What are the direct factors that control eating?
Orosensory effects (4Ts: taste, texture, temp, + to smell)
Food in the GI tract (mechano-, chemo-, osmo-rec.)
= stimuli that directly engage receptors in the mucosa of the alimentary tracts
What are indirect factors that influence eating?
Metabolic factors and body temperature
Postingestive effects of digested nutrients
GI hormones
Rhythms (circadian, hormonal, annual cycles)
Learned effects (preferences, and aversions)
Cognitive factors (dietary awareness, beliefs)
Cultural, ethnical, social, economical factors
= effects that are not derived from a direct receptor interaction with a meal
What are general features of hormones that affect food intake?
Released from the GI tract in response to intraluminal nutrients
Regulate appetite acting directly on CNS receptors, or indirectly via nX.
Some are synthesized and released also in the brain
Potential therapeutic targets
What are the anorexigenic GI hormones?
CCK PYY PP, amylin glucagon incretin hormones: GLP-1
