Exam 3 - GI Histology 2 Flashcards
1
Q
What are major structural features that increase surface area for absorption in the GI tract ?
A
- length of snall and alrge intestine
- plicae circulares (valves of kerckring)
- Villi
- Microvilli
2
Q
What is the histology of the crypt villus system?
A
- Each villus cotains a core of lamina propria
- crypts extends down between the villi below the abses of the villi
- crypts and villi consititute glands of the small intestine
- wall villus is composed of a simple columnar epithelium with goblet cells
- each villus contains a capillary plexus
- each villus contains a blind ending lymphatic reffered to as a lacteal
3
Q
What is the fine structure of a microvillus system
A
- Covered with glycoprotein and glyocalyx
- Bundles of actin filaments within microvillus is covered by aformin cap
- supported by a core of actin microfilaments
- actin filaments are tied to terminal web intermediate filaments (cytokeratins) via spectrin fibrils
- ACtin filaments are bound to plasma membrane covering villus via membrane-linking proteins
- myosin 1 and calmodulin
- Actin Fialments are boudn to each other via actin cross- linking proteins
- villin and fimbrin
4
Q
What is the glycocalyx?
A
- a glycolipid coat that contins an array of brush border enzymes
- maltase, sucrase, isomaltase, lactase, lipase, peptidase
- produced by small intestinal epithelial cells
5
Q
A
6
Q
What are the three orders of folding?
A
- Plicae ( folds of mucosa wach with submucosal core)
- Crypt-villus system
- Microvillus
7
Q
know this photo
A
8
Q
What is the shape of villus and the histological characteristics of the duodenum?
A
- Villi with wide spatulate or leaflike distal shape
- deep crypts of lieberkuhn
- brunners glands with excretory ducts in submucosa
9
Q
What is the shape of villus and the histological characteristics of the jejunum?
A
- Vili longer and narrow
- crypts of leiberkuhn present
- no glands in submucosa
10
Q
What is the shape of villus and the histological characteristics of the ileum?
A
- Villi narrow and shorter than in jejunum
- crypts of leiberkuhn present
- no glands in submucosa
11
Q
What is the histology of the crypt of lieberkuhn ?
A
- Simple tubular glands within the intestinal mucosa
- open between adjacent villi and extend to muscularis mucosa
- cells of crypt
- Goblet cells
- Enterocytes
- columnar epithelial cells with……
- produce disaccharides
- involved in absorption of proteins, carbohydrates, lipids
- enzymes present on apical brush border are important in carbohydrate digestion
- produce enteriopeptidase (enterokinase) necessary for activation of pancreatic zymogens and proenzymes
- columnar epithelial cells with……
- Paneth cells
- basal crypt cells
- prominent eosinophillic grnaules
- produce lysozyme to control intestinal flora
- Enteroendocrine cells
- stains with chromium (chromaffin)
- agryophillic (respond to sliver stains)
- produces peptide hormones and serotonin
- paracrine or autocrine secretions
- = to unicellular goblet cells
- formed from endoermal stem cells in all regions of GI
12
Q
What is the brunner gland and where is it found?
A
- Found in submucosa of duodenum
- fomration of bicarbonate and mucus
- supplements bicarbonate from pancreas and necessary to neutral gastric acid
13
Q
What is the function of the large intestine ?
A
- Epithelium
- simple columnar epithelium
- cryprts no villi
- Functions
- secretion of mucous for lubrication
- goblet cell is prominent cell of the large intestine
- absorption of fluid
- formation of fecal mass
- continuation of digestion initiated in small intestine
14
Q
A
15
Q
What does the small intestine consist of and what of are the layers of its wall?
A
- Consists….
- duodeum
- jejeunum
- ileum
- Layers (inside to outside)
- Mucosa with lamina propria and muscularis mucosa
- submucosa
- muscularis layers
- serosa
16
Q
A
17
Q
A
18
Q
A
19
Q
A
20
Q
A
