The document summarizes key aspects of gut structure and function. It describes the layers of the gut wall and pH ranges throughout the gastrointestinal tract. The buccal cavity, esophagus and stomach have a small surface area, while the duodenum and small intestine have a very large surface area of 10-14 feet. Transit times are shortest in the buccal cavity, esophagus and stomach at 30-40 minutes, while the large intestine has the longest transit time of up to 24 hours.

2. Gut structure
• Mucosa
• Submucosa
• Muscularis externa
• Serosa

5. • Regarding the PH range is as the following
• A) For buccal cavity the PH is approximately 7
• B) Esophagus PH is 5-6
• C) Stomach PH is 1-3, decomposition of some drugs
occurs here & weak acids are un-ionized
• D) Duodenum PH is 6-6.5 contains ducts & surfactant
properties
• E) Small Intestine PH is around 7-8
• F) Large Intestine PH is about 5.5-7

6. pH of the Gastrointestinal Contents of
Various Species∗

7. Regarding the Surface Area
A)Buccal cavity, esophagus & stomach have a small
surface area
B) Duodenum have a very large surface area
C) Small intestine have a very large 10-14 ft
D) The large intestine doesn’t have very large area,
about 4-5 ft

8. Regarding the Transit Time
A) Buccal Cavity have a short unless controlled
time
B) Esophagus have a short time
C) Stomach have 30-40 minutes (small time)
with reduced absorption
D) Duodenum have a very short window effect
E) The small intestine have about 3 hours
F) The large intestines have a long one up to 24
hours

9. Regarding the Transit Time
A) Buccal Cavity have a short unless controlled
time
B) Esophagus have a short time
C) Stomach have 30-40 minutes (small time)
with reduced absorption
D) Duodenum have a very short window effect
E) The small intestine have about 3 hours
F) The large intestines have a long one up to 24
hours