Histology Intestines Flashcards
Shortest and widest part of small intestine?
Duodenum
Principle site for digestion of food?
Small intestine
- absorption here
- synthesis and secretion of digestive enzymes
- control microbial growth
Small intestine regulates GI function via the ____ secretion by ____ cells.
Endocrine secretion by enteroendocrine cells
Unique feature of the small intestine? What do they contain?
Presence of place circulares- permanent transverse folds that contain a core of submucosa
Contain both mucosa and submucosa
Plicae are most numerous in the _____ and _____ and increase the surface for absorption.
Distal duodenum and proximal jejunum
Most unique feature of the mucosa of the small intestine is the presence of what?
Villi
The core of the villus is formed by ______ of the _____.
Loose CT of the lamina propria
NO submucosa in the villus
Enterocytes are responsible for the _____ of ____ and produce _____.
Absorption of nutrients and produce digestive enzymes
Where does the final stage of digestion of carbohydrates and proteins occur?
Glycocalyx of the intestinal absorptive cells
Lipids are broken down into monoglycerides and fatty acids within the _____. They diffuse across the ______ and are resynthesized into triglycerides in the _____ of the ______. Fat droplets are then transported to the ____ where they acquire a protein coat and become ______. They then bud and are transported to eh basolateral surface of the absorptive cell where they are released into the _____.
Lumen of the intestine Absorptive cell membranes Smooth ER Intestinal absorptive cell Golgi apparatus Chylomicra Extracellular space
Enterocytes are also involved in transcytosis of ___ from the lamina propria of the intestinal lumen. What is this synthesized by? What does it protect and regulate?
IgA
Synthesized and secreted by plasma cells in lamina propria
Protect mucosa by regulating microbial growth
Enterocytes contain what on the apical surface? What are they bounded by?
Microvilli
Tight and anchoring junctions
Narrow base, wide apex, mucinogen granules, small triangular and heterochromatic nucleus that is nasally placed
Goblet cells
Found in the epithelium overlying lymphoid follicles
M-cells
M-cells are ____ cells. They convey microorganisms and other macromolecules from the epithelial lumen to the ____.
Antigen-transporting
Lymphoid follicles
Large, dome-shaped cells, filled with macrophages, dendritic cells, and lymphocytes. Covered by microfolds.
M-cells
Unusual type of T-lymphocytes. Blood-derived. Involved in providing mucosal immunity.
Intraepithelial lymphocytes
What two cell types are foun dint he crypts of Lieberkuhn but not the surface epithelium?
Paneth cells and progenitor cells
What is found at the bottom of the crypts of Lieberkuhn?
Paneth cells- regulate normal bacterial growth
Most prominent feature of Paneth cells?
Numerous large, refractive eosinophilic granules int he apical portion of the cell
- granules contain antibacterial enzyme lysozyme, alpha defensins
- basal part of cell has well-developed RER
Large associations of lymphoid follicles are found where? What are they called? What do they contain?
Ileum, called Peyer’s patches
Consists mainly of M-cells
Blood supply to lamina propria consists of ____ that begin from the arteriolar of the submucosal vascular plexus and return to the venues of the same plexus. What is transported by blood vessels? What isn’t?
Capillary loops
Soluble nutrients unlike chylomicra
Each villus contains a central blind-ended lymphatic capillary called a ____. These drain into large lymphatic vessels within the ____. What do they transport?
Lacteal
Submucosa
Transport lipids in the form of chylomicra produced by enterocytes
Submucosa of the small intestine is typical for the rest of the alimentary canal and consists of _____ and the ___ plexus.
Dense CT
Vascular and nerve- Meissner’s
Mucous-producing branched tubular glands most abundant in the proximal part of the duodenum. Purpose?
Brunner’s glands- neutralize acid-containing chyme
Where is the Auerbach’s plexus found?
Muscularis externa between the inner circular and outer longitudinal layer
Adventitia or serosa?
Duodenum
Jejunum
Ileum
Duodenum- mostly adventitia, some serosa
Jejunum and ileum- serosa
Features of duodenum
Submucosa Brunner’s glands
Least amt of goblet cells
Features of jejunum
Tallest villi and most prominent lacteals
More of a rule out
Features of the ileum
Peyer’s patches, highest concentration of goblet cells
Villi are shorter
Principal function of the large intestine?
Reabsorption of electrolytes and water AND elimination of undigested food and waste
How is the mucosa of the large intestine different?
No villi, no paneth cells
More abundant goblet cells
What is foun dint he deeper parts o the crypts of Lieberkuhn in the large intestine?
Progenitor cells
In the muscularis externa of the large intestine, the other longitudinal muscle layer forms three thickened equally spaced bands called what?
Teniae coli
The ___ of the large intestine contains small fatty projections called the _____ which are visible on the outer intestinal surface.
Serosa
Omental appendices
Taeniae coli is absent from what two things?
Appendix and rectum
What contains a large number of aggregated lymphatic follicles?
Vermiform appendix
Rectum contains prominent folds called what?
Transverse rectal folds
