GIT hormones are

CCK Secretin

VIP Somatostatin

Motilin Glucagon

Entero-glucagon Neurotensin

GRP Villikinin

Gastrin

Gastrin

1-Site of release:

G- cells in the antral part of gastric mucosa and duodenal mucosa

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)

GastrinActions:

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

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Somatostatin

Site of release:M cells in small intestine(duodenum and jejunum)

StimulusUnknown, although some studies suggest that an

alkaline pH in the duodenum stimulates its release

Motilin

Actions:1-increases the migratory motor complex

villikinin

Local hormone released by intestinal mucosa

stimulus: digestive products of food.

Action: it stimulates movements of villi and help absorption.