0219 - Control of Body Weight Flashcards
Describe Grehlin and how it is involved in appetite regulation.
The only compound that stimulates hunger. Made in stomach (particularly fundus), and is at highest levels during fasting, with levels falling within 1 hour of food intake.
Describe Cholecystokinin (CCK) and how it is involved in appetite regulation.
One of many satiety compounds. Secreted by endocrine cells in GIT in response to feeding - at lowest level during fasting.
Describe Glucagon like peptide-1 (GLP-1) and how it is involved in appetite regulation.
One of many satiety compounds. Product of pre-proglucagon in GI and CNS, at lowest during fasting, and increased by feeding.
Describe Peptide YY (PYY) and how it is involved in appetite regulation.
One of many satiety compounds. Produced by gut endocrine cells, lowest during fasting, increased by feeding.
What are the major satiety compounds produced in the GI tract?
Cholecystokinin - CCK
Glucagon Like Peptide-1 - GLP1
Peptide YY - PYY
Describe Leptin and its role in appetite regulation.
A medium/long term satiety compound that is the protein product of Obesity gene in adipose tissue. Absence or deficiency in mice causes obesity.
Plasma level correlates with adipose tissue mass, with obesity representing a form of leptin resistance.
Works on the brain (hypothalamus), with a diurnal pattern of secretion - nadir 0900-1100, peak 0000-0400 (keep you full at night).
What are the two adipose-tissue based satiety compounds?
Leptin - obesity= leptin resistance. Medium/long term signalling.
Adiponectin (poorly understood) - inversely related to body weight.
What are the pancreatic satiety compounds?
Amylin - Decreases short-term food intake
Insulin - Levels proportionate to adipose tissue, reduces feeding by inhibiting NPY, enhancing CCK effects
Pancreatic Polypeptide - May reduce appetite and food intake in humans.
Describe neural homeostatic regulation of appetite
Arcuate Nucleus (hypothalamus) controls. Neurons which express Neuropeptide Y (NPY), Agouti-related Peptide (AgRP) stimulate food intake. Neurons which express pro-opiomelanocortin (POMC) have opposite effect.
In paraventricular nucleus (Hypothalamus), TRH, CRH, and oxytocin (hunger-suppressing) are produced.
In lateral hypothalamus, MCH and Orexins (hunger stimulating) are produced.
Which compounds are short-term (meal-to-meal) and which are medium-long term in appetite regulation?
Short term - Grehlin, CCK, GLP-1, Amylin, PP, PYY
Medium/long - Leptin, Insulin
Describe the role of sensory and hedonic factors in regulating body weight?
Sensory and hedonic factors can override the satiety homeostatic satiety signals received in the orbitofrontal cortex to produce the reward value of food. This can lead to increased appetite and eating despite abundant energy stores and food supply.
In what order are macronutrients oxidised?
Oxidised in order that is inverse to amount body can store.
Alcohol, then protein, then carbohydrates, then fats.
Which is the most and least satiating macronutrients?
Protein is most satiating, then CHO, then fat. (leaving alcohol out).
How many calories per gram of each of the macronutrients?
KEY EXAM CONCEPT
Fat - 9
Alcohol - 7
Carbs - 4
Protein - 4
