GI Tract

Question 1

What is the general function of the gastrointestinal tract?

Answer 1

To digest and absorb nutrients from ingested food, eliminate waste, and serve endocrine and immune functions

Question 2

What are the four major layers of the GI tract wall (from innermost to outermost)?

Answer 2

1. Mucosa
   
   2. Submucosa
   3. Muscularis externa
   4. Serosa (or adventitia)

Question 3

What are the components of the mucosa layer?

Answer 3

• Epithelium (varies by region)
• Lamina propria (connective tissue with blood vessels and lymphatics)
• Muscularis mucosae (thin smooth muscle layer)

Question 4

What is the role of the submucosa?

Answer 4

It supports the mucosa and contains:
• Blood vessels
• Lymphatics
• Nerve plexus (submucosal/Meissner’s plexus)
• Glands (in certain regions)

Question 5

What is the function of the muscularis externa?

Answer 5

Responsible for peristalsis and segmentation; typically has:
• Inner circular layer
• Outer longitudinal layer
• Controlled by myenteric (Auerbach’s) plexus

Question 6

What is the difference between serosa and adventitia?

Answer 6

• Serosa: a slippery visceral peritoneum layer in intraperitoneal organs
• Adventitia: a fibrous connective tissue covering retroperitoneal organs

Question 7

What are the main functions of the mouth in digestion?

Answer 7

• Mechanical digestion (chewing or mastication)
• Chemical digestion (salivary enzymes)
• Formation of the bolus
• Initiates swallowing (deglutition)