Digestive System 3 Flashcards
What do the intestines of a mammal consist of?
- small intestine (duodenum, jejunum, ileum)
- large intestine (cecum, colon, rectum, anal canal)
What is the tissue found in the small intestine?
simple columnar epithelium
+ striated border
What tissue is the large intestine composed of?
simple columnar epithelium
+ striated border
What other cells, except of simple columnar epithelium, can be found in the intestines?
goblet cells
How is the tunica muscularis of the intestines organised?
What type of cells?
- inner circular layer
- outer longitudinal layer
smooth muscle cells
How do the intestines compare from a histological point of view?
They are very similar.
duodenum, jujenum, ileum are very similar; but also, small and large intestines are very similar.
What is the outermost layer of the intestines? Why?
Tunica Serosa
- serous cells provide secrete which lubricates the surface of intestines,
- allows intestines to glide against other organs
What is the second layer of the intestines (from the outside)?
Tunica Muscularis
- outer longitudinal layer
- inner circular layer
- (both layers = smooth muscle cells)
What is the 3rd layer (counting from the outside) of the intestines? What tissue is it based on?
Tunica Submucosa
- based on loose connective tissue
What is the final tissue layer of the intestines (most inner layer)? What cells is it composed of?
Mucosa:
- simple columnar epithelium
- striated border
What is meant by the “striated border” of the intestines?
“striated border” = microvilli
What are ‘microvillis’?
very small projections located on EACH simple columnar epithelial cell.
What do microvilli provide the intestines with? Why is this necessary?
- microvilli increase the intestinal surface area
- necessary to absorb water and nutrients more effectively
What is the major difference between the histological structure of the small and large intestine?
villi!
(only found in the small intestine)
What is the special structure of the small intestine?
villi
What are the differences in villi between species?
ruminants: short and thick
carnivores: long and slender
What is located at the bases of villi?
Invaginations of the epithelium called the intestinal glands.
What are the invaginations in the epithelium at the villi bases called?
intestinal glands
What occurs in the invaginations? How does it occur? What is a different name of the villi invaginations?
invaginations = intestinal glands
- replacement of the mucosal epithelium
- by cell division
By what process is mucosal epithelium replaced?
cell division
What is a distinctive feature of the small intestine?
Mucosa takes up a very large portion of the entire intestinal wall/organ.
- 80% of entire wall
- 20% remaining layers (tunica submucosa, muscularis and serosa)
What type of projections can be spotted in the small intestine?
outer projections: villi
inner projections: intestinal glands
What other organ has glands in the digestive system? What are their names?
stomach
gastric glands (in gastric pits)
What is the difference between glands in the stomach and small intestine?
stomach- gastric pits
small intestine- intestinal glands
stomach: invaginations (gastric pits) which only later open into gastric glands