LESSON 6: DIGESTIVE SYSTEM LBBBIO7
FIRST TRIMESTER | 2025-2026
■ Adventitia: fibrous tissue covering
SYNCHRONOUS SESSION areas outside the peritoneal cavity
(e.g., esophagus, retroperitoneal
structures like the rectum)
The Digestive System and the Accessory organs and glands
○ Myenteric (Auerbach’s) Plexus
■ Autonomic nerve plexus
● Histology of the Alimentary Tract (parasympathetic)
○ We will also discuss accessory organs and glands ■ Regulates peristalsis
such as the salivary glands, gallbladder, and liver.
General Histological Features
● Layers of the Alimentary Tract:
○ Mucosa ● Summary of Layers:
■ Epithelium ○ Mucosa → Epithelium + Lamina propria +
■ Basement membrane or lamina Muscularis mucosae
propria ○ Submucosa → Glands, blood vessels, nerve
■ Muscularis mucosae – smooth muscle plexus
that helps with contraction ○ Muscularis externa → Inner circular + Outer
■ The epithelium, basement membrane, longitudinal + Myenteric plexus
and muscularis mucosae together ○ Lumen → Central space
make up the mucosa, the innermost ○ Serosa / Adventitia → Outermost layer
layer of the GIT
○ Submucosa Pharynx
■ Located beneath the mucosa
■ Contains blood vessels, lymphatic
nodules, and nerve plexuses
○ Muscularis externa
■ Inner circular layer – smooth muscle
(spindle-shaped)
■ Outer longitudinal layer – circular
bands
● Nasopharynx
■ The inner circular layer is adjacent to
○ Respiratory function
the submucosa
○ Lined by pseudostratified tall columnar
○ Serosa / Adventitia
epithelium
■ Serosa: outermost layer made of
● Oropharynx
visceral peritoneum
○ Posterior to the oral cavity
● Parietal peritoneum: lines
○ Lined with non-keratinized stratified squamous
the peritoneal cavity
epithelium for protection against friction and
● Visceral peritoneum: covers
wear and tear from food passage
the organs (viscera)
● Laryngopharynx (Hypopharynx)
LBBBIO7: Histology Laboratory LESSON 6 1
FIRST TRIMESTER | 2025-2026
■ Adventitia: fibrous tissue covering
SYNCHRONOUS SESSION areas outside the peritoneal cavity
(e.g., esophagus, retroperitoneal
structures like the rectum)
The Digestive System and the Accessory organs and glands
○ Myenteric (Auerbach’s) Plexus
■ Autonomic nerve plexus
● Histology of the Alimentary Tract (parasympathetic)
○ We will also discuss accessory organs and glands ■ Regulates peristalsis
such as the salivary glands, gallbladder, and liver.
General Histological Features
● Layers of the Alimentary Tract:
○ Mucosa ● Summary of Layers:
■ Epithelium ○ Mucosa → Epithelium + Lamina propria +
■ Basement membrane or lamina Muscularis mucosae
propria ○ Submucosa → Glands, blood vessels, nerve
■ Muscularis mucosae – smooth muscle plexus
that helps with contraction ○ Muscularis externa → Inner circular + Outer
■ The epithelium, basement membrane, longitudinal + Myenteric plexus
and muscularis mucosae together ○ Lumen → Central space
make up the mucosa, the innermost ○ Serosa / Adventitia → Outermost layer
layer of the GIT
○ Submucosa Pharynx
■ Located beneath the mucosa
■ Contains blood vessels, lymphatic
nodules, and nerve plexuses
○ Muscularis externa
■ Inner circular layer – smooth muscle
(spindle-shaped)
■ Outer longitudinal layer – circular
bands
● Nasopharynx
■ The inner circular layer is adjacent to
○ Respiratory function
the submucosa
○ Lined by pseudostratified tall columnar
○ Serosa / Adventitia
epithelium
■ Serosa: outermost layer made of
● Oropharynx
visceral peritoneum
○ Posterior to the oral cavity
● Parietal peritoneum: lines
○ Lined with non-keratinized stratified squamous
the peritoneal cavity
epithelium for protection against friction and
● Visceral peritoneum: covers
wear and tear from food passage
the organs (viscera)
● Laryngopharynx (Hypopharynx)
LBBBIO7: Histology Laboratory LESSON 6 1
