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Transcript 
GUT PHYSIOLOGY
Secretion 1
Dr. Jack Grider
Rm 12-004 Sanger Hall
828-1853
[email protected]
2009
Secretions
Secretions
• Serious component
– Water
– Electrolyte (H/Na/K/Cl/ HCO3)
• Protein or mucus component
– Mucopolysaccharide
– Glycoprotein
– Protein as digestive enzyme
Secretions
Tubular Gland
Mucous Gland
Compound Gland
Secretions
Depending on the gland, secretion is the result of
Increases in intracellular Ca++ and/or cAMP
Salivary Secretion
Three glands: parotid, submaxilary, sublingual
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•
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•
•
•
•
Mucous
Amylase (ptyalin)
Lingual Lipase
Lysozymes
IgA
Growth Factors
Serous component
•
•
•
•
•
•
•
Lubricates& neutralize
Starch digestion
Lipid digestion
Antibacterial action
Immune protection
Protective to mucosa
Taste/sensory stimulation/
pH neutralization
Salivary Secretion
Salivary Secretion
• Hormonal Control
• Neural control
– Parasympathetic nervous system
– Sympathetic nervous system
Salivary Secretion
Salivary Amylase: pH Optimum=7
Lingual lipase: pH optimum = 4
Gastric Secretion
•
•
•
•
•
Mucus
HCl
Intrinsic factor
Pepsinogen/pepsin
Lipase
Gastric Secretion
Gastric tubular glands or gastric pits in Proximal Stomach
Gastric Secretion: Mucous
Viscous fingering of HCl through mucus
HCl through H2O
HCl through mucin
Bhaskar et al., Nature 1992
Gastric Secretion: Mucous
Mucous layer provides protection for mucosal cells
and forms a pH gradient.
Gastric Secretion:HCl
Canaliculi
Tubular
Vesicles
Unstimulated
Stimulated
Gastric Secretion
H2O + CO2 + NaCl -----> NaHCO3 + HCl
Gastric Secretion
Gastric Secretion
Neural control mechanisms
FUNDUS
ANTRUM
Gastric Secretion
Hormonal & paracrine control mechanisms
Amino Acid
ANTRUM
FUNDUS
Gastric Secretion
Paracrine control mechanisms: Feedback regulation
SSt also inhibits oxyntic cell in fundus
Gastric Secretion
• Gastric secretion divided into 3 periods
– Cephalic
– Gastric
– Intestinal
Gastric Secretion
Cephalic phase
Gastric Secretion
Cephalic Phase to Gastric Phase
Gastric Secretion
Gastric phase
Gastric Secretion
Intestinal Phase
• Decline in stimulation
• Paracrine somatostatin released as pH falls
• Duodenal signals are inhibitory
–
–
–
–
secretin
CCK (competitive antagonism)
GIP
neural
Gastric Secretion
A similar curve would describe gastrin secretion
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