GI Tract Flashcards
1
Q
General Structure of the GI Tract
A
Mesentary
- wall around the tube (protective membrane)
Serosa
- serous producing glands
- internal visceral layer
- outside parietal layer
- Secretion between the two to establish a boundary
2 Layers of Muscle
- Muscularis Externa - longitudinal
- Muscularis Mucosa - goes around the tube
Mucosa layer
- invaginations into the lumen to increase surface area for absorption of proper nutrients
- contains Plica Circularis
Submucosa
- behind mucosa
- lymphoid nodules and some glands
2
Q
Esophagus
A
Mucosa
- Epithelial portion - stratified squamous non keratinized
- Some glands
- layer of smooth muscle - muscularis mucosa
Muscularis Externa
- longitudinal muscle
- skeletal muscle and smooth muscle
- lumen in very small compared to other portions of GI tract
3
Q
Esophago-gastric Junction
A
- Where the esophagus meets the stomach
- Epithelium changes
- Goes from stratified squamous to simple columnar epithelium which invaginates as gastric pits
4
Q
Cardiac Stomach
A
- Simple Columnar epithelium
- Gastric pits - invaginations
- Cardiac Glands - mucous secreting
5
Q
Body and Fundus Stomach
A
- Large cavity
- many folds inside the body to expand the surface area (called rugae)
- Gastric pits become deeper and the glands become more complex
6
Q
Pyloric Stomach
A
- Deeper gastric pits
- short pyloric glands which are coiled tubular branched
- secretes mostly mucous
7
Q
Surface mucous cells
A
- on the surface of gastric pits
- secrete mucous
- serves as protection, preserves the content
8
Q
Mucous neck cells
A
- under surface mucous cells
- secrete mucous
9
Q
Parietal Cells
A
- Produce HCl and intrinsic factor
- needed for digestion
- When active - they secrete HCl
- there is a rearrangment of intracellular organelles when active
- More microvilli increase the surface are so there is more secretion
- Have a prominent Golgi and a lot of mitochondria due to their secretory nature
10
Q
Chief Cells
A
- also called zymogenic cells
- Produce lipase - cleave lipids
- Takes care of any lipid content in the food
- Produce pepsinogen that is made into pepsin
11
Q
G cells
A
- Produce gastrin
12
Q
Enteroendocrine Cells
A
- Called Argentaffin cells because you use silver stain to find these
- secrete serotonin
13
Q
HCl Production
A
- Secreted by parietal Cells
- Production consumes ATP - involves active transport
- Carbonic anhydrase - synthesizes bicarbonate
- Protons are channeled to the outside
- Bicarbonate ion is exchanged with Cl
- Cl is released with H to form HCl
14
Q
Transition from the Stomach to the Intestine
A
- Duodenum is the beginning of the small intestine
- Change in mucosa from gastric pits to intestinal villi
- Sphincter- circle of smooth muscle that opens and closes at the end of stomach - Pyloric sphincter
- There is an increase in amount of microvilli for increased surface area for absorption
15
Q
Structure of the small intestine
A
- Large number of glands and microvilli
Glands of Liberkuhn
- Goblet Cells - Secrete mucous
- Paneth Cells - secrete serous
- Absorptive Cells- able to absorb whats coming in GI Tract
- Argentiffin - endocrine cells
- Dividing cells constantly push cells upwards for replacement
- lymphocytes that give a connection with immune system
Microvilli contain some of the same cells
- Formed by actin
- Fibrin bridges between filaments of actin
- Villin - protein that forms the top of the microvilli
- smooth muscle inside
- Blood circulation and lymphoid circulation inside
- some nervous connection in submucosa and muscle
