Metabolic Hormones Flashcards
Where is gastrin produced?
G cells in distal stomach
Where is secretin produced?
duodendum
Where is cholecystokinin produced?
Duodenum
Where is gastric inhibitory peptide produced?
Duodenum
Where is glucagon-like peptide (GLP-1) produced?
Ileum L cells
Where is motilin produced?
duodenum and jejunum
Where is ghrelin produced?
Stomach
What is the release stimuli for gastrin?
Presence of peptides and AA in the stomach
Stomach distention
Vagal stimulation
Hypercalcaemia
What are the effects of gastrin?
Stimulates release of gastric acid from parietal cells
Stimulates pepsinogen release from chief cells
What is the release stimuli for secretin?
H+ in the small intestine
What are the effects of secretin?
This signals to the exocrine pancreas that food is on its way and it should start secreting bicarb and digestive enzymes now
What is the release stimuli for Cholecystokinin CCK?
Fatty acids, monoglycerides and AA in the small intestine
What are the effects of Cholecystokinin?
This is the gall bladder squeezing hormone, when products of digestion reach the duodenum then CCk signals for the exocrine pancreatic secretion. CCK is more enzymes and secretin is more bicarb.
What is the release stimuli for Gastric Inhibitory Polypeptide?
Fat, glucose and amino acids in small intestine
What are the effects of Gastric Inhibitory Polypeptide?
Inhibits gastric secretion and motility (tries to deal with the large amount of food coming)
Causes release of insulin in response to elevated blood glucose concentration
Stimulation of lipoprotein lipase activity in adipocytes
What does GLP-1 do?
GLP-1 is stimulated when it senses too much nutrient in this part of the gut so it tells us to slow down food movement and tells us to stop eating (as well as telling the pancreas to secrete insulin)
Suppresses glucagon driven gluconeogenesis
Slowed gastric emptying
Promotes satiety (hypothalamus)
What is the release stimuli for motilin?
Secretion is associated with fasting
(?) high pH in the duodenum
What are the effects of Motilin?
Maintains motility in the stomach and intestine
Stimulates the production of pepsin
What does leptin do?
Leptin causes satiety (anorexigenic)
What does ghrelin do?
Ghrelin stimulates appetite (orexigenic)
What does the satiety centre respond to?
Responds to high glucose levels
Inhibits eating
What does the appetite centre respond to?
Responds to low glucose levels
Stimulates eating
Where do the appetite and satiety centres lie?
Satiety lies either side of the ventral third ventricle
Appeteite centre lies laterally to this
What is the lipostat hypothesis of obesity?
Adipose tissue produces a hormonal signal- leptin
Leptin level proportionate to the amount of fat
Signal acts upon membrane bound receptors in the hypothalamus to decrease food intake and increase energy output.
Genetic lack of leptin leads to obesity so Leptin can be described as an anorexigenic hormone
What is the CCK (appetite) /peptide YY hypothesis?
CCK is synthesised in the small intestine and acts upon G protein coupled receptors.
CCK also found in cells in the brain - expansion of the stomach after a meal causes release of CCK from these brain cells. This release of CKK slows gastric emptying ad decreases food intake.
What is the Ghrelin hypothesis?
Produced predominantly by the lining of stomach (also from intestine and hypothalamic nuclei).
Increases before meals, decreases after.
Stimulates appetite at hypothalamus
Ghrelin can be described as an orexigenic hormone
Ghrelin receptors are also found in other areas of the brain, including the hippocampus and regions known to be involved in reward systems
