Page 201 - Physiology and Pathophysiology MNU 2024-2025 نظرى

Clinical pharmacy 2024/2025 Level 2 Pharm D Physiology and Pathophysiology (MD303)

4) Digestive tract wall

The digestive tract wall has the same basic structure from the esophagus till the colon.
The four major layers within the wall are:

a. Mucosa
b. Submucosa
c. Muscularis externa

d. Serosa

1- Mucosa

• Lines luminal surface of digestive tract
• Highly folded surface  greatly increases absorptive area.

• Three layers:
Mucous membrane Lamina propria

• Serves as protective surface. Houses gut-associated lymphoid tissue
• Modified for secretion & absorption. (GALT)  Important in defense against
• Contains disease-causing intestinal bacteria

a. Exocrine gland cells  secrete
digestive juices. Muscularis mucosa

b. Endocrine gland cells  secrete Sparse layer of smooth muscle
blood-borne gastrointestinal

hormones.
c. Epithelial cells  specialized for

absorbing digestive nutrients

2- Submucosa

• Thick layer of connective tissue
• Provides digestive tract with distensibility & elasticity.

• Contains larger blood and lymph vessels.
• Contains nerve network known as submucosal plexus.

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