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					             GIT hormones are


Gastrin
CCK                             Secretin
VIP                         Somatostatin
Motilin                         Glucagon
Entero-glucagon                 Neurotensin
GRP                              Villikinin
 Gastrin
1-Site of release:
G- cells in the antral part of gastric mucosa and
duodenal mucosa
Types

        Gastrin 34
        • 34 amino acid
        • Big gastrin
        • Secrete during the
          interdigestive period
          (between meals)
        • Secreted at low basal levels
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)
    Cholecystokinin (pancreozymin)
Site of release:
Mucosa of the upper small intestine (jejunum)


Stimulus:
 digestive products of   fats and proteins (+ve feedback)
 less by acids
synthesized as a pre-prohormone

It has 2 types of receptors:

1)CCK A in the pancreatic acinar cell
2)CCK B in brain and stomach
Cholecystokinin (pancreozymin)
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
    Secretin
Site of release:
Mucosa of the upper small intestine as prosecretin
and activated by acid into secretin
Stimulus:
   acid chyme (-ve feedback)
Secretin
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
     Vaso-active intestinal peptide (VIP)
Site of release:
Glands and neurons throughout the intestine

Stimulus:
   neural stimulation
 distension
Acid chyme
Vaso-active intestinal peptide (VIP)
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
        Somatostatin
         Growth Hormone Inhibiting Hormone (GHIH) or Somatotropin
                        Release-Inhibiting Factor


Site of release:
D- cells in pancreas , GIT mucosa and hypothalamus

Stimulus:
   according to site of release
Somatostatin
    Actions:
    Stomach: -- secretions & motility
    Small intestine: -- secretions & motility
_
    Pancreas: -- secretions
    Gall bladder: -- evacuation
  Motilin
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

 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.

				
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posted:9/14/2012
language:Latin
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