Intestines Flashcards
What is the length of the jejunum and ileum?
Jejunum is 2.5 m and ileum is 3.5 m
What features increase the surface area in the small intestines?
Plicae circulares (valves of kerckring), villi/crypts, and microvilli (with brush border)
Do crypts of intestinal villi cross the muscularis mucosae?
No
What type of epithelium is present in the small intestine?
Simple columnar
The simple columnar epithelium of small intestines is populated by what 5 types of cells?
- Enterocytes 2. Goblet cells
- EEC/APUD cells 4. Paneth cells
- Stem cells
What provides protection from invasive microorganisms in the small intestines?
- sIgA 2. tight junctions between enterocytes 3. GALT
Where are goblet cells highest in frequency: duodenum, jejunum, ileum, large intestine?
Goblet cells increase in frequency toward the large intestine.
What type of stem cells are present in the small intestine?
Pleuripotential cells
Where are APUD cells found in the small intestines?
In crypts
Where is sertonin secreted?
EC cells in the small intestine and fundus of the stomach
What cells secrete CCK?
I cells in the small intestines
What cells secrete secretin?
S cells in the small intestines
What is the function of secretin?
stimulates pancreatic and biliary bicarbonate and water secretion
What is the function of somatostatin?
Inhibits parietal and chief cell secretion
What is the function of chief cells?
secrete pepsinogen
What layer of the small intestine contains smooth muscle cells?
Lamina propria
Where are Brunner’s glands found?
submucosa of the duodenum
Where are Peyer’s patches found?
submucosa of the ileum
What is the function of Brunner’s glands?
secretes a clear alkaline mucin into neck of crypts (protection against acid chyme)
Define Peyer’s patches.
GALT, covered by M cells, important in immune response
True or False: M cells are APC’s
FALSE. They are NOT APC’s.
What is the difference between the mucosa of the large intestine versis the mucosa of the small intestine?
The mucosa of the large intestine has no villi and no plicae circularis. Crypts/glands are still present.
What is the difference between the mucsularis externa of the large intestin and the muscularis externa of the small intestine?
The outer longitudinal muscle layer of the large intestine is formed by 3 longitudinal stripes called TANEA COLI
How are the layers of the colon different from the rectum?
The rectum lacs tanea coli
What is the embryonic origin of the proximal 1/2 of the anal canal?
Endoderm
What is the embryonic origin of the distal 1/2 of the anal canal?
Ectoderm
What is the dividing point between the upper and lower anal canal?
Pectinate line
What type of epithelium is found above the pectinate line?
Simple columnar
What type of epithelium is found below the pectinate line?
Non-keratinized strafied squamous
Where is the most likely place to get hemorrhoids?
Lamina propria at the pectinate line contains large plexus of veins.
Where are anal columns located?
Upper anal canal
What is the blood supply of the anal canal above the pectinate line?
Superior rectal artery (branch of the IMA)
What is the blood supply of the anal canal below the pectinate line?
Inferior rectal artery (branch of the internal pudendal artery)
What is the internal anal sphincter composed of?
thickened inner circular layer of muscularis externa
