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GIT hormones. GIT hormones are CCK Secretin VIP Somatostatin Motilin Glucagon Entero-glucagon Neurotensin - PowerPoint PPT Presentation
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GIT hormones are
CCK Secretin
VIP Somatostatin
Motilin Glucagon
Entero-glucagon Neurotensin
GRP Villikinin
Gastrin
Gastrin 34
• 34 amino acid• Big gastrin• Secrete during the
interdigestive period (between meals)
• Secreted at low basal levels
Types
Stimulus for release:
gastric distension
chemical factors (secretagogues) e.g. amino acid , coffee, alcohol, vegetables.
vagal stimulation (bombesin)
Gastrin
Actions:
Stomach: ++ secretions (HCL)
++ pyloric pump
trophic factor to the mucosa
Small intestine: ++ motility
Pancreas: ++ secretions (enzymes)
Site of release:
Mucosa of the upper small intestine (jejunum)
Stimulus:
digestive products of fats and proteins (+ve feedback)
less by acids
Cholecystokinin (pancreozymin)
synthesized as a pre-prohormonesynthesized as a pre-prohormone
It has 2 types of receptorsIt has 2 types of receptors : :
11((CCK A in the pancreatic acinar cellCCK A in the pancreatic acinar cell22((CCK B in brain and stomachCCK B in brain and stomach
3- Actions:
Pancreas: * ++secretions ( rich in enzymes by action
on pancreatic acini )
* augment secretin * stimulates glucagon secretion
Stimulate pancreatic growth
Gall bladder:++ evacuation (cholagogue)
Small intestine: ++ secretions & motility
Stomach: -- secretions (HCL) & motility
Cholecystokinin (pancreozymin)
Secretin
Site of release:
Mucosa of the upper small intestine as prosecretin and activated by acid into secretin
Stimulus:
acid chyme (-ve feedback)
Actions:
Pancreas: * ++secretions (copious and very alkaline by action on pancreatic ducts)
*augment CCK
Biliary:++bile rich in H2O+HCO3(choleretic
Stomach: -- secretions & motility
Small intestine: ++ secretions but -- motility
Secretin
Vaso-active intestinal peptide (VIP)
Site of release:
Glands and neurons throughout the intestine
Stimulus:
neural stimulation
distension
Acid chyme
Actions:
Pancreas: * ++secretions (copious and alkaline by action on pancreatic ducts)
Stomach: -- secretions & relax smooth muscles &
stimulating pepsinogen secretion by chief cells
Small intestine: ++secretions but relax smooth muscles
Blood vessels: vasodilatation
Vaso-active intestinal peptide (VIP)
SomatostatinGrowth Hormone Inhibiting Hormone (GHIH) or Somatotropin Growth Hormone Inhibiting Hormone (GHIH) or Somatotropin
Release-Inhibiting FactorRelease-Inhibiting Factor
Site of release:
D- cells in pancreas , GIT mucosa and hypothalamus
Stimulus:
according to site of release
Actions:
Stomach: -- secretions & motility
Small intestine: -- secretions & motility
Pancreas: -- secretions
Gall bladder: -- evacuation
_
Somatostatin
Site of release:M cells in small intestine(duodenum and jejunum)
Stimulus
Unknown, although some studies suggest that an alkaline pH in the duodenum stimulates its release
Motilin
Actions:
1-increases the migratory motor complex