GI1&2 - Purpose & Anatomy of the Gut

Question 1

3 features of the enteric nervous system

Functions x5
Location x2

Answer 1

1. ) Functions - semi autonomous and controls:
   - immune and motor functions, blood flow, secretions, transport across the mucosa
2. ) Location - in the submucosa (Meissner’s plexus) and between the external muscle layers (Auerbach’s plexus)
3. ) Is heavily linked with the autonomous nervous system

Question 2

What are the 4 layers of the gut tube?

Answer 2

1. ) Mucosa (innermost) - selectively permeable layer between the gut lumen, made up of epithelium, lamina propria, and muscularis mucosae
2. ) Submucosa - contains DCT, blood vessels, glands, lymphoid tissue
3. ) Muscularis Propria - contains inner circular muscle and outer longitudinal muscle
4. ) Serosa - continuous with mesenteries, contains blood, lymph vessels and fat

Question 3

What are 6 specialised cells/structures in the gut?

Answer 3

1.) Enterocyte - involved in absorption, contains microvilli to increase SA, found in the intestines

2. ) Goblet Cells - secrete mucus to protect gut epithelium from friction, chemical damage and bacteria.
   - increases in number from the duodenum to the colon
3. ) Folds - rugae, pilica circulares, haustra
4. ) Villi - projections in the SI into increase SA
5. ) Crypts - invaginations of the epithelial surface of the intestines
   - contain stem cells, paneth cells, enteroendocrine cells

6.) Epithelial Cells - stratified squamous in oesophagus and distal anus, simple columnar everything in between

Question 4

What are the 3 types of folds in the internal surface of the gut?

Answer 4

1. ) Rugae - temporary folds in the stomach
2. ) Pilica Circulares - permanent folds in the SI
3. ) Haustra - folds that result from the contraction of longitudinal muscle layers (sacculations) in the LI

Question 5

What are the 4 major muscle groups that form the anterolateral abdominal wall?

Answer 5

1. ) External Oblique
2. ) Internal Oblique
3. ) Transverse Abdominus - lateral muscles with flat tendons (aponeuroses) that project anteriorly to form the rectus sheath
4. ) Rectus Abdominus

Question 6

4 features of the peritoneum/peritoneal cavity

Parietal and Visceral Peritoneum
Peritoneal Cavity
Mesentery
Structures

Answer 6

1. ) Parietal and Visceral Peritoneum
   - parietal is in contact with the abdominal wall whilst the visceral envelops the abdominal viscera
2. ) Peritoneal Cavity - lined with mesothelium, enclosed in males but open in females (fallopian tubes)
3. ) Mesentery - double layer of peritoneum, in between the layers are blood and lymph vessels and fat
4. ) Structures - are either intraperitoneal or retroperitoneal
   - intra: abdominal viscera enveloped in the peritoneum
   - retro: abdominal viscera that lie behind the peritoneum