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25 Cards in this Set

  • Front
  • Back
Salivary glands produce salivary amylase (also known as ptyalin)
Stomach (fundus, body, and pylorus)
-Pepsin (derived from chief or zymogenic cells which produce pepsinogen)
-Hydrochloric acid (derived from parietal cells)
-Intrinsic factor (made by parietal cells)
Small intestine (in luminal membranes of epithelial cells.
-Enterokinase (activates trypsin from trypsinogen)
-Aminopeptidase (peptides to amino acids)
The four processes carried out by the GI tract
digestion, secretion,
absorption, and motility.
-Pancreatic amylase (carbohydrates)
-Pancreatic lipase (lipids)
-Trypsin (protein peptides)
Trypsin activates the other enzymes
-Chymotrypsin (protein peptides)
-Carboxypeptidase (peptides to amino acids)
Digestive secretions
from the liver and the pancreas are
delivered into the duodenum of the small intestine through
the sphincter of Oddi.
Stomach Lining
-The mucosa in the stomach is thrown into folds called rugae.
-The lining of the stomach has numerous openings leading down into the mucosa called gastric pits.
-From these pits emerges the pepsin and HCl.
-Folds in the stomach lining are called “rugae.”
-They increase the surface area of the stomach wall.
One inhibitory and
three stimulatory
signals that alter
acid secretion by
parietal cells
in the stomach.
-Gastrin +
-Histamine +
-ACh +
-Somatostatin -
Acid production by the parietal cells in the stomach depends on
the generation of carbonic acid; subsequent movement of hydrogen ions into the gastric lumen results from primary active transport
Chief cells
synthesize and secrete the protease precursor known as pepsinogen.
Parietal cells
synthesize and secrete the hydrochloric acid responsible for the acidic pH in the gastric lumen.
By projecting
into the lumen,
the villi increases
the surface area
for absorption of

Microvilli [aka brush
border] fringe the
villi to further increase
surface area.
Release of Pancreatic Enzymes and Bicarbonate
-Now it is known that enzyme release and bicarbonate release are controlled by different hormones.
-Cholecystokinin causes release of enzymes from the pancreatic acinar cells.
-Secretin causes the release of bicarbonate from the pancreatic duct cells.
Cholecystokinin-Pancreozymin CCK-PZ or Simply CCK
-Cholecystokinin discovered by Ivy and Oldberg in 1923. They described the contraction of the gall bladder
-Pancreozymin discovered by Harper and Raper 1943. Demonstrated that it caused secretion of pancreatic enzymes.
-Now know that the above are actually the same molecule.
Cholecystokinin (CCK)
stimulates the gallbladder, which responds by contracting and
delivering more
bile to the duodenum
through the sphincter
of Oddi, which relaxes (opens) in response to CCK.
Basal Granulated Cells of the GI Tract
Two types:
-Argentaffin (silver reducing) cells. Cells of the GI tract capable of reducing silver salts to metalic silver. Are also known as enterochromaffin cells (EC cells)
-Argyrophile (silver absorbing) cells. Cells can cause silver to precipitate, but only after treatment with an extraneous reducer.
Gastrointestinal Hormones
-Collectively they comprise the largest gland in the body.
-Great delay in determining the product of the cells because they are scattered throughout the GI tract.
-Hindered by the fact that many proteinases are present (trypsin, pepsin, etc.).
-It was the 1970s before much progress was made.
Is produced in the stomach wall by basal granulated cells known as G-cells.
ED Cell
D Cell
L Cell
EC Cell --Motilin
D Cell -- Somatostatin
L Cell -- CCK
APUD Cells
Amine Precursor Uptake and Deamination
- there is a whole family of these types of cells
-possibility of origin from the neural crest
Bile salts and
convert large fat globules into smaller pieces with polar surfaces that inhibit reaggregation.
Emulsified fat globules
small enough that lipase
enzymes gain access to
degrade triglycerides
to monoglycerides and
fatty acids, which enter
the absorptive cells by
simple diffusion or aggregate to form loosely held micelles, which readily break down.
Big Droplets of Fat -->
Small Droplets of Fat-->
Fatty Acids and
Chylomicron Assembly-->
Distribution and Processing
Bile formation by cells in the liver includes 6 components:
bile salts, lecithin, bicarbonate ions, cholesterol, bile pigments, and trace metals.
-The bile is funneled into the gallbladder and then delivered
into the duodenum upon stimulation from CCK.
of the small intestine
Most of the contractions
of the small intestine are
of the mixing and churning
actions portrayed here as
segmentation contractions;
peristalsis and the
downstream movement
of materials is infrequent.