Phys + Pharm of intestines Flashcards
Where in the GI tract is Gastrin secreted from?
From G cells in the gastric antrum (mainly) and duodenum
Where in the GI tract is Cholecystokinin secreted from?
From I cells in the duodenum and jejunum
Where in the GI tract is Secreten secreted from?
From S cells of the duodenum
Where in the GI tract is Motilin secreted from?
From M cells of the duodenum and jejunum
What would parasympathetic nerve activity do to the levels of Secretion in the small intestine?
Enhance it.
What would excessive activity of secretions in the small intestine cause?
Secretory Diarrhoea (Cholera)
What does small intestine secretion contain?
Mucus - (for protection/lubrication)
Aqueous salt - (For enzymatic digestion)
NO DIGESTIVE ENZYMES
What are the two different categories of pancreatic secretions?
Endocrine - insulin + glucagon (Into blood)
Exocrine - digestive enzymes, aqueous NaHCO3 solution (Into duodenum as pancreatic juice)
Explain how the Pancreas knows to release NaHCO3 solution into the duodenum.
Acid in the duodenal lumen causes incresed Secretin release from S cells.
Carried in the blood this then triggers the Pancreatic duct cells to increase secretion of NaHCO3 into the duodenal lumen.
How does the pancreas know to release digestive enzymes into the duodenum?
Fats and proteins in the duodenal lumen lead to increased CCK release from I cells.
This then triggers the Pancreatic acinar cells with increase secretion of digestive enzymes into the duodenal lumen.
Explain the cephalic phase of secretion?
Mediated by vagal stimulation of (mainly) the acinar cells
Explain the Gastric phase of secretion.
Gastric distension evokes vagovagal reflex resulting in parasympathetic stimulation of acina and duct cells.
What is absorbed in the large intestine?
H2O
Na+ + CL-
Short chain fatty acids
What is secreted in the large intestine?
K+
HCO3- (Neutralises)
Mucus
