Gut Hormones Flashcards
What are the two forms of gastrin
G34
G17
When is gastrin produced
Antrum
When is gastrin released
High pH
Stimulated by proteins, peptides and amino acids
What are the two actions of gastrin
Acid secretion from parietal cells
Growth promoting effects on gastric mucosa
Hypergastrinaemia occurs in…
Decreased acid production (atrophic gastritis)
Overuse of PPI
zollinger ellison syndrome
Which cells secrete CCK and where
I cells
Small intestine
CCK release is stimulated by…
Ingestion of fat and protein
What are the 3 actions of CCK
Gallbladder contraction and bile acid release
Regulates gastric emptying and bowel motility to induce satiety
Regulates meal stimulated pancreatic secretion
Which conditions are associated with a low CCK
Coeliac disease
Bulimia
Which condition are CCK levels reportedly high
Chronic pancreatitis
Which cells secrete secretin
S cells
When is secretion released
Stimulated by acid in duodenum
What are the actions of secretin
Pancreatic and bicarbonate secretion neutralising acidic chyme in intestine
Inhibits gastric acid, gastric secretions and intestinal motility
Aids osmoregulation of hypothalamus and pituitary
Where is VIP released from
Neurones in gut, pancreas
What is the action of VIP
Vasodilator = smooth muscle relaxation
Secretion of electrolytes into lumen
Neuromodulator of sphincters of GI tract
What does a lack of VIP lead to?
Hirschsprungs
What does excessive VIP lead to
WDHA
Watery diarrhoea
Hypokalaemia
Achlorhydria
Which cells produce glucagon
Alpha cells in pancreas
What is the action of glucagon
Regulates glucose homeostasis:
Gluconeogenesis
Glycogenolysis
Lipolysis
Where is gastric inhibitory polypeptide released
K cells in duodenum, jejunum mucosa
What is the action of GIP cells
Inhibit gastric acid secretion
Stimulate insulin release in hyperglycaemic state
Augments triglyceride storage contributing to fat accumulation
Where is pancreatic polypeptide released
Endocrine cells of pancreas
Describe pancreatic polypeptides actions
Self regulation of pancreatic secretory activity
Affects hepatic glycogen levels and GI secretions
Somatostatin is produced in the…
D cells
When is somatostatin released
Influenced by pH
Mechanical stimulation
Dietary component (fat, protein, glucose)
Actions of somatostatin
Regulate gastric acid secretion
Reduce pepsinogen secretion
Inhibit bicarbonate and pancreatic enzyme release
Reduce bile flow
Reduce gut motility
Reduce splanchnic blood flow
Lepton blood levels reflect total body fat stores, but where is it released from
Chief and adipose cells in stomach
How does lepton regulate food ingestion?
Lowers neuropeptide Y levels (a potent stimulator of food intake within the brain)
Where is ghrelin produced
P/D1 cells in gastric fundis, pancreas, pituitary
Describe the actions of ghrelin
Stimulate gastric contraction
Enhance stomach emptying
Initiation of ingestion
LEVELS HIGH WHEN HUNGRY
Where is motilin produced
Endocrine cells in duodenum
Motilins secretion is periodic and not affected by food ingestion, but what are its actions?
Increase migrating myoelectric complex of GI motility
Stimulate pepsin production
Peristalsis in small intestine in preparation for next meal
What does substance P primarily mediate?
Neurogenic inflammation
What is the role of substance P
Activate vomiting reflex
Involvement in nociception
High levels of substance P found in UC and Crohn’s
In relation to satiety signals, what is the role of CCK
Delays gastric emptying
Signals termination of food ingestion
In relation to satiety signals what is the role of ghrelin
Initiates meal ingestion
Levels rise rapidly before a meal and fall rapidly afterwards
In relation to satiety signals what is the role of glucagon like peptide
Delays gastric emptying
Increases satiety
In relation to satiety signals what is the role of leptin
Reduced food intake
Produces greater reduction in body weight
In relation to satiety signals what is the role of neuropeptide Y
Increases food intake
Increases proportion of food stored as fat
In relation to satiety signals what is the role of peptide YY
Reduced calorie intake
Inhibits gastric motility
Increases water and electrolyte absorption in colon
