Lecture 20: Basic structure of the GI Flashcards
What is the role of the Gl system?
Bring nutrients/water into internal environment to be used by the body
MSDA (My Sausage Dog Ate)
* Motility: transport food into & through the body,
mixing luminal contents, and transport waste out
- Secretion: synthesise and release enzymes,
mucus & serous fluid into the lumen - Digestion: break nutrients into smaller pieces
(mechanically and chemically) - Absorption: bring nutrients/water from the lumen to
internal environment
What are the majors organs of the digestive tract?
Oral cavity (mouth)
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
What are the accessory organs of the organs of the digestive system?
Teeth/tongue
Salivary glands
Liver
Gall bladder
Pancreas
What structure separates parts of the digestive system and allows for unique environments in each organ?
Sphincters close off ends, and separate sections of tube. This allows for unique environments to be achieved within the digestive tract.
What is the epithelia found in the mouth and esophagus?
Stratified squamous epithelium - allows protection from rough foods etc.
What type of epithelia is found in the stomach, small intestine and large intestine?
Simple columnar epithelium - Good for secretion and absorption of nutrients/water etc.
What are unicellular glands in the GI system?
Goblet cells: (mucus secreting)
* Columnar
* Goblet shape
* Apical mucous granules
* Basal nucleus
What type of epithelium is found at the anus?
Stratified squamous epithelium - provides protection from abrasion
What are the two types of multicellular glands in the GI system?
Epithelium can invaginate to form glands:
- Simple: gland with single duct (e.g. stomach and small
intestine) - Compound: gland with 2 or more ducts (e.g. salivary
glands) = more surface area for greater secretion
What are the four gut tube layers (in order from in to out)?
- Mucosa
- Submucosa
- Muscularis (externa/proper)
- Adventitia
What does the mucosa layer consist of?
- Epithelium
- Basement membrane
- Lamina propria (FCT)
- Muscularis mucosae
Plus, sometimes, glands
What does the submucosa consist of?
- FCT
- Glands
- Blood vessels
How is secretion regulated in the submucosa?
Secretion is regulated by the submucosal nerve plexus, part of the enteric nervous system (ENS)
What does the muscularis consist of? What are the two main layers and what regulates the muscular motility?
The muscularis (externa/proper) consists of smooth muscle
Two main layers:
* Inner circular
* Outer longitudinal
The Myenteric plexus (Part of ENS), Located between muscle layers regulates motility of the muscles
What does the adventitia consist of?
It is the Outermost layer of the gut tube and consists of FCT