Page 202 - Physiology and Pathophysiology MNU 2024-2025 نظرى

Clinical pharmacy 2024/2025 Level 2 Pharm D Physiology and Pathophysiology (MD303)
3- Muscularis Externa

• Major smooth muscle coat of digestive tube
• In most areas consists of two layers:

a. Circular layer b. Longitudinal layer
• Inner layer • Outer layer
• Contraction   diameter of • Contraction  shortens the tube
lumen
• Contractile activity produces propulsive and mixed movements.
• Myenteric plexus: Lies between the two muscle layers.

4- Serosa

1- Secretes serous fluid:
Lubricates  prevents friction between digestive organs & surrounding viscera.

2- Continuous with mesentery throughout much of the tract
a. Attachment provides relative fixation.

b. Supports digestive organs in proper place while allowing them freedom for
mixing & propulsive movements.

5) Regulation of GIT by autonomic nervous system

Parasympathetic nervous system [M3] Sympathetic nervous system
Stimulate motility and GI secretions Reduce motility and GI secretions

6) Gastrointestinal tract organs

1- Mouth:

➢ The first step in the digestive process is chewing, or mastication  initial mechanical
breakdown of the food  facilitates its movement to the stomach.

➢ This mixes food with saliva.
➢ Saliva contains:

Component Functions:

99.5% of saliva is water.

a. Water: a. Moistening of food materials  facilitate Swallowing.
b. Solvent for molecules that stimulate the taste buds.

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