Digestive System
consists of
gastrointestinal tract / alimentary canal
accessory digestive organs
food enters the tract at the mouth and is processed by the organs
the contents that leave the system at the end of the tract are primarily undigested food
what you need to know:
That mucous membranes line body cavities that are open to the outside.
The histological makeup of mucous membranes.
The types of epithelial tissues and their functions.
Anatomy : wall of GI tract
The histological organization of the 4 layered wall in the GI tract is similar from the stomach to the last
portion of the anal canal
Throughout the tract, modifications of the histological organization serve regional functions.
Small intestine
The villi, microvilli, and intestinal crypts are
specific modifications of the small intestine.
functions of the GI epithelium include
secretion of substances used in
digestion
absorption of the digested products
mucosa
An epithelium, made up of columnar cells, forms the inner or luminal boundary of the tract.
lamina propria
a connective tissue layer
underlies the epithelium
carries blood and lymph vessels.
muscularis mucosae
A thin sheet of smooth muscle
forms the deep boundary of this layer
Functions of the GI epithelium include:
Secretions of substances used in digestion
, Other epithelial cells secrete fluids (such
as acid in the stomach and water and
salts in the small intestine)
Secretory products are released into the
lumen
enteroendocrine cells
individual mucosal cells
The hormones of the GI system are
produced and secreted by this
They are present over a large area
Stimuli for release are in the lumen or near
the basal surface of the cells.
hormones are released into the interstitial
fluid to enter capillaries of the lamina propria
Hormones are not released into the lumen
of the GI tract.
lacteals
Nutrients are absorbed across a single layer
of cells into blood capillaries or lymph
vessels called this
As we leave the mucosa, note that there are
stem cells present throughout the GI tract
that divide continuously to replace epithelial
cells that are regularly shed.
A new epithelium is produced every three to
consists of
gastrointestinal tract / alimentary canal
accessory digestive organs
food enters the tract at the mouth and is processed by the organs
the contents that leave the system at the end of the tract are primarily undigested food
what you need to know:
That mucous membranes line body cavities that are open to the outside.
The histological makeup of mucous membranes.
The types of epithelial tissues and their functions.
Anatomy : wall of GI tract
The histological organization of the 4 layered wall in the GI tract is similar from the stomach to the last
portion of the anal canal
Throughout the tract, modifications of the histological organization serve regional functions.
Small intestine
The villi, microvilli, and intestinal crypts are
specific modifications of the small intestine.
functions of the GI epithelium include
secretion of substances used in
digestion
absorption of the digested products
mucosa
An epithelium, made up of columnar cells, forms the inner or luminal boundary of the tract.
lamina propria
a connective tissue layer
underlies the epithelium
carries blood and lymph vessels.
muscularis mucosae
A thin sheet of smooth muscle
forms the deep boundary of this layer
Functions of the GI epithelium include:
Secretions of substances used in digestion
, Other epithelial cells secrete fluids (such
as acid in the stomach and water and
salts in the small intestine)
Secretory products are released into the
lumen
enteroendocrine cells
individual mucosal cells
The hormones of the GI system are
produced and secreted by this
They are present over a large area
Stimuli for release are in the lumen or near
the basal surface of the cells.
hormones are released into the interstitial
fluid to enter capillaries of the lamina propria
Hormones are not released into the lumen
of the GI tract.
lacteals
Nutrients are absorbed across a single layer
of cells into blood capillaries or lymph
vessels called this
As we leave the mucosa, note that there are
stem cells present throughout the GI tract
that divide continuously to replace epithelial
cells that are regularly shed.
A new epithelium is produced every three to
