GI hormones Flashcards
What cell type secretes gastrin?
G cells
Where are G cells located?
Antrum
Duodenum
What factors increase gastrin secretion?
Amino acids
Peptides
Gastric distension
Increased pH
Parasympathetic (using GRP)
What receptors does Gastrin act at?
CCK2 receptor called CCK-B
How does gastrin affect the stomach?
Parietal cells: inc. HCl, IF secretion
Chief cells: inc. pepsinogen, gastric lipase
Mucosal cells: inc. # and size
ECL cells: inc. histamine release
What cells secrete histamine?
ECL
Mast cells
Where are ECL and mast cells located?
Gastric glands
GI mucosa
What factors increase secretion of histamine?
Gastrin
Parasympathetic
Gastric distension
What receptor does histamine act on?
H2
What affect does histamine have on the stomach?
Parietal cells: increase HCl, IF
Chief cells: increase pepsinogen, gastric lipase
How is carbonic acid distributed from the parietal cell?
acid is pumped out to lumen
Bicarbonate is pumped out to blood on basolateral end of cell
How is H+ pumped out of parietal cell?
H,K - ATPase: recycles potassium to pump out acid
What cells secrete cholecystokinin?
I cells
Where are I cells located?
Duodenum
Jejunum
What factors increase secretion of CCK?
From CCK releasing peptide:
Fatty acids
Amino acids
Peptides
Monitor Peptide
What receptor does CCK act at?
CCK1 receptor called CCK-A
Where do CCK’s actions have effect?
Pancreas
Gallbladder
Sphincter of Oddi
Gastric emptying
CNS
What effect does CCK have?
Pancreas:
Acinar cells = inc. enzyme release
Ductal cells = potential HCO3 secretion by secretin
Gallbladder = contraction
Sphincter of Oddi = relaxation (via NO)
Gastric emptying = slowed
CNS = increases feeling of fullness
What cells secrete Secretin?
S cells
Where are S cells located?
Duodenum
Jejunum
What factors increase secretion of secretin?
Low pH
Fatty acids
What receptor does secretin act on?
SCTR
Where does secretin’s actions have effect?
Pancreas
Bile duct
G cells
Gastric emptying
What effect does Secretin have?
Pancreas
Ductal cells = inc. HCO3 secretion
Acinar cells = potentials enzyme release by CCK
Bile duct = inc. HCO3 secretion
G cells = dec. gastrin release
Gastric emptying = slowed
What cells secrete Somatostatin?
D cells
Where are D cells located?
Stomach
Small intestines
Pancreas
What factors increase SST secretion?
Low pH
Fatty acids
Amino acids
Peptides
What receptor does SST act on?
SSTR
Where do SST’s actions have an effect?
Stomach
Duodenum
Pancreas
Gallbladder
What effects does SST have?
Stomach:
G cells = dec. gastrin release
Parietal cells = dec. HCl, IF
Chief cells = dec. pepsinogen, gastric lipase
Duodenum
I cells: decrease CCK release
Pancreas
Acinar cells: dec. enzyme
Beta cells = dec. insulin release
Alpha cells = dec. glucagon release
Gallbladder = dec. contraction (mostly from dec. CCK around)
What cells secrete glucose-dependent insulinotropic peptide?
K cells
Where are K cells located?
Duodenum
Jejunum
What factors increase GIP secretion?
Glucose
Fatty acids
What receptor does GIP act on?
GIP receptor
What actions does GIP have?
Pancreas
Beta cells: inc. insulin release
Gastric emptying: slowed
What cells secrete motilin?
M cells
Where are M cells located?
Duodenum
Jejunum
What factors increase motilin secretion?
Fasting
What receptor does motilin act on?
Motilin receptor
What actions does Motilin have?
Migrating motor complex (MMC):
Peristaltic sweep
Relaxes pyloric sphincter
What does intrinsic factors help with?
Vitamin B12 absorption
What effects do vagal stimulation have on GI hormones?
Chief cells: inc. gastric lipase, pepsinogen
Parietal cells: inc. HCl, IF
ECL cells: inc. histamine
G cells: inc. gastrin
What effect does prostaglandin stimulation have on GI hormones?
Surface mucous cells: inc. HCO3, mucus, trefoil peptides
Chief cells: dec. gastric lipase, pepsinogen
Parietal cells: dec HCl, IF
What cells secrete bicarbonate?
Pancreatic duct cells
Parietal cells
