Taste
Taste buds
Epithelial structures within
stratified epithelium lining
dorsum of tongue
Four Layers of the Digestive System Wall
1) Mucosa
a) Epithelium: stratified squamous non-keratinized;
simple columnar with/without microvilli
b) Lamina propria: areolar connective tissue; glands may
be present
c) Muscularis mucosa: smooth muscle
2) Submucosa: areolar connective tissue; glands may be
present; nerve plexus
3) Muscularis
a) Inner: circular smooth muscle typically
b) Outer: longitudinal smooth muscle typically
c) Nerve plexus
4) Adventitia/Serosa: loose connective tissue with/without
serous membrane (visceral peritoneum)
Intrinsic nerve plexuses
Myenteric nerve plexus
Submucosal nerve plexus
Glands in submucosa
Mucosa
Epithelium
Lamina propria
Muscularis mucosae
Submucosa
Muscularis externa
Longitudinal muscle
Circular muscle
Serosa
Epithelium
Connective tissue
Mesentery
Nerve
Artery
Gland in mucosa
Vein
Duct of gland outside
Lymphatic vessel
alimentary canal
Lumen
Mucosa-associated
lymphoid tissue
(a) Longitudinal and cross-sectional views through the small intestine
Myenteric nerve plexus
Lies between circular and longitudinal
muscularis
Controls peristalsis and segmentation
Submucosal nerve plexus
Lies in submucosa
Signals glands to secrete
Innervation
Sympathetic and parasympathetic motor
fibers
Visceral sensory fibers
The Esophagus
• Gross anatomy – muscular tube
– Begins as a continuation of the pharynx
– Joins the stomach inferior to the diaphragm
• Cardiac sphincter – closes lumen to prevent
stomach acid from entering esophagus
The Esophagus
• Microscopic anatomy
– Epithelium is stratified squamous
epithelium
– When empty – mucosa and submucosa in
longitudinal folds
– Mucous glands – primarily compound
tubuloalveolar glands
– Muscularis externa
• Skeletal muscle first third of length
– Adventitia – most external layer
Microscopic Structure of the Esophagus
Figure 22.17a, b
Figure 23.18d Microscopic
anatomy of the stomach.
( Plicae + Villi + Microvilli) = 600-fold increase in surface area
Mucosa
Submucosa
Muscularis externa
Serosa
(b) Light micrograph cross section through the small intestine (30)
Absorptive cells
Goblet
cells
Villi
(c)
Intestinal crypt
Absorptive cells
Lamina propria
Goblet cells
Intestinal crypts
Muscularis
mucosae
Lobule
(b)
Central vein
Connective
tissue septum
Microscopic Anatomy of the Liver
• Some functions of hepatocytes
– Rough ER manufactures blood proteins
– Smooth ER produces bile salts, detoxifies
poisons
– Peroxisomes detoxify poisons (alcohol)
– Golgi apparatus packages secretory
products
– Mitochondria provide energy for liver
processes
– Glycosomes store sugar
– Great capacity for regeneration
The Peritoneal Cavity and
Peritoneum
• Peritoneum – a serous membrane
– Visceral peritoneum – surrounds digestive
organs
– Parietal peritoneum – lines the body wall
• Peritoneal cavity – a slit-like potential
space
The Peritoneal Cavity and
Peritoneum
• Mesentery – a
double layer of
peritoneum
– Holds organs in
place
– Sites of fat storage
– Provides a route for
circulatory vessels
and nerves
Figure 22.9a
The Peritoneal Cavity and
Peritoneum
• Retroperitoneal
organs
– Behind the
peritoneum
• Peritoneal organs
– Digestive organs that
keep their mesentery
Figure 22.9b
Secondarily Retroperitoneal
Organs
•
•
Initially formed within peritoneum
Become retroperitoneal
– Fuse to posterior abdominal wall
Figure 22.11
Summary of Intraperitoneal and
Secondarily Retroperitoneal Organs
Table 22.1
Mesenteries
Figure 22.10a
Mesenteries
• Lesser omentum attaches to lesser curvature of stomach
Figure 22.10b
Mesenteries
• Greater
omentum – a
“fatty apron” of
peritoneum
• Greater omentum
and transverse
colon reflected
Figure 22.10c
Mesenteries
• Sagittal section
through the
abdominopelvic
cavity
• Mesenteries attach
to posterior
abdominal wall
Figure 22.10d
Peritoneal cavity
lesser and greater sacs
epiploic foramen
Mesenteries
1) falciform ligament
2) lesser omentum
3) greater omentum
4) “the mesentery” of the small
intestine
5) transverse mesocolon
6) sigmoid mesocolon
Liver:
1) Falciform ligament
Liver to anterior abdominal
wall
2) Lesser omentum
Liver to lesser curvature of
stomach
Coronary ligament is reflection
of peritoneum from liver to
diaphragm
Epiploic foramen (f. of Winslow)