Gastrointestinal Lecture 1 Part 3 Intestinal Wall Flashcards
What is the “shape” of the digestive system?
Tube with functional segmentation
Basic Anatomy of the digestive system
layers of Cross-section of the intestinal wall
- epithelium
- basement membrane - lamina propia
- muscularis mucosa
- submucosa
- circular muscle
- myenteric plexus
- longitudinal muscle
- Mesothelium (serosa)
Epithelium
“Barrier” of cells that nutrients must traverse to be absorbed into the body
What is in the submucosa?
Capillaries and lymphatics aid transport to and from intestine - absorb nutrients from the tract
Circular and longitudinal layers
Circular and longitudinal layers of smooth muscle allow motile contractions of the intestine - not voluntary
myenteric plexus
Rich nerve supply controls multiple aspects of motility and secretion
Sections of the epithelium layer
- endocrine cells
- exocrine cells
- mucous cells
endocrine cells of the epithelium
Secrete hormones into blood that regulate digestion and appetite
exocrine cells of the epithelium
Secrete substances into lumen that aid digestion (e.g. acid, enzymes, water, ions,…)
Mucous cells of the epithelium
give rise to ducts from accessory organs (e.g. salivary glands, pancreas) to secret fluid to Gi tract when necessary
What are sphincters of the GI tract?
Rings of muscle creating a constriction point in the tube
- Open/closing regulates flow through the tract
- Prevents backflow
What are the sphincters of the GI tract?
- Upper esophageal (pharynx/esophagus)
- Lower esophageal (esophagus/stomach)
- Pyloric (stomach/small intestine)
- Ileocecal (small intestine/large intestine)
- Internal anal (rectum/anus)
- External anal (rectum/anus
Where are each of the sphincters located?
