Digestive System

Front 1

Mouth

Back 1

Salivary glands produce salivary amylase (also known as ptyalin)

Front 2

Stomach (fundus, body, and pylorus)

Back 2

-Pepsin (derived from chief or zymogenic cells which produce pepsinogen)
-Hydrochloric acid (derived from parietal cells)
-Lipase
-Intrinsic factor (made by parietal cells)

Front 3

Small intestine (in luminal membranes of epithelial cells.

Back 3

-Enterokinase (activates trypsin from trypsinogen)
-Sucrase
-Maltase
-Lactase
-Aminopeptidase (peptides to amino acids)

Front 4

The four processes carried out by the GI tract

Back 4

digestion, secretion,
absorption, and motility.

Front 5

Pancreas

Back 5

-Pancreatic amylase (carbohydrates)
-Pancreatic lipase (lipids)
-Trypsin (protein peptides)
Trypsin activates the other enzymes
-Chymotrypsin (protein peptides)
-Carboxypeptidase (peptides to amino acids)

Front 6

Digestive secretions

Back 6

from the liver and the pancreas are
delivered into the duodenum of the small intestine through
the sphincter of Oddi.

Front 7

Stomach Lining

Back 7

-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.

Front 8

One inhibitory and
three stimulatory
signals that alter
acid secretion by
parietal cells
in the stomach.

Back 8

-Gastrin +
-Histamine +
-ACh +
-Somatostatin -

Front 9

Acid production by the parietal cells in the stomach depends on

Back 9

the generation of carbonic acid; subsequent movement of hydrogen ions into the gastric lumen results from primary active transport

Front 10

Chief cells

Back 10

synthesize and secrete the protease precursor known as pepsinogen.

Front 11

Parietal cells

Back 11

synthesize and secrete the hydrochloric acid responsible for the acidic pH in the gastric lumen.

Front 12

Villi

Back 12

By projecting
into the lumen,
the villi increases
the surface area
for absorption of
nutrients.

Microvilli [aka brush
border] fringe the
villi to further increase
surface area.

Front 13

Release of Pancreatic Enzymes and Bicarbonate

Back 13

-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.

Front 14

Cholecystokinin-PancreozyminCCK-PZ or Simply CCK

Back 14

-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.

Front 15

Cholecystokinin (CCK)

Back 15

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.

Front 16

Basal Granulated Cells of the GI Tract

Back 16

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.

Front 17

Gastrointestinal Hormones

Back 17

-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.

Front 18

Gastrin

Back 18

Is produced in the stomach wall by basal granulated cells known as G-cells.

Front 19

ED Cell
D Cell
L Cell
-secrete?

Back 19

EC Cell --Motilin
D Cell -- Somatostatin
L Cell -- CCK

Front 20

APUD Cells

Back 20

Amine Precursor Uptake and Deamination
- there is a whole family of these types of cells
-possibility of origin from the neural crest

Front 21

Bile salts and
phospholipids

Back 21

convert large fat globules into smaller pieces with polar surfaces that inhibit reaggregation.

Front 22

Emulsified fat globules

Back 22

are
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.

Front 23

Big Droplets of Fat -->

Back 23

Small Droplets of Fat-->
Micelles-->
Fatty Acids and
Monoglycerides-->
Chylomicron Assembly-->
Distribution and Processing

Front 24

Bile formation by cells in the liver includes 6 components:

Back 24

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.

Front 25

contractions
of the small intestine

Back 25

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.