Intestine Mircoanatomy Flashcards
What are the layers of the digestive tract
Lecture Slide
Mesenteric artery and vein
Mesentary
Serosa
Muscualris
Submucosa
Mucosa
Plica
- Villi
- Mucosa (Mucosal epithelium, lamina porpria)
- Mucosal glands
-submucosal glands
-musclaris mucosae
-lymphatic vessle
-artery and vein
- Submucosal plexus
-cicular muscle layer
myenteric plexus
Longitudal muscle layer
Histology slide of ileum
Lecture Slide
Celiac disease affects the gut how
autoimmune disease that attacks cells of villi
↳ Villus atrophy - destruction of villi (less SA)
· less absorption
· less digestion
↳ malabsorption
Role of lacteals
lacteals :
-blinded-ended capillary at core of villus
-lymphatic vessel
-no smooth muscle in walls
-rely on smooth muscle fibres inside the villus to help propel contents along
-smooth muscle fibres are extensions of the muscularis mucosae into the villus
What part is the villus, intestinal gland, mucosa and submucosa
Lecture Slide
What transports carbs
What transports lipids
Transport of carbohydrates (monosaccharides), proteins (amino acids), water and electrolytes. Venules in the submucosa are tributaries of the hepatic portal vein.
Transport of absorbed lipids. Lymphatic vessels eventually drain into the venous system.
Mucosa of the small intestine:
What cells
Columnar absorptive cells (enterocytes): Absorb the small molecules resulting from digestion
Role of micorvilli
microvilli membrane (lipid bilayer) studded with enzymes
- Directly digest items eg glycosidases help to breakdown carbs
- enterokinase activate pancreatic enzymes coming from pancreas
Role fo goblet cells
Components
Secrete mucus for lubrication
Mucinogen granules filling apical cytoplasm and Basal nucleus
Enteroendocrine cells:
- role
- what is bile made from
enteroendocrine cells to m ake Cholecystokinin (CCK)
Bile:
chyme
HCl
fatty acids
amino acids
What does CCK do
What does HCl do
Act on gallbladder to release bile
act on pancreas to release digestive enzymes
HCl:
activates secertin which acts on duodenum (increase bicarb production) and stomach (stop gastrin release)
Undifferentiated cells:
role
Stem cells dividing to generate new epithelium
↳ near base of glands
more upwards to replace superficial cells
Paneth cells
release what
TNF-a (produces inflammation in response to bacteria and parasites)
Lysozyme (bactericidal; destroys bacterial membranes)
Defensins (increasees ion channels in cell membranes of invading organisms; increases permeability)
Compare duodenum, jejnum and ileum
duodenum 25cm
Macroscopically curvy (c shaped), secrete bicarb, rich in mucus to neutralise acid
jejnum 2.5m
lots of plicae cicurlais and villi for lots of digestion and abs
ileum 3.5m
leads into large intestine and theres lots of bacteria (flora) lots of defensive mechanisms
Label chunk of intestine diagram
Lecture Slide
Label small intestine histo
Lecture Slide
Label plica histo
Lecture Slide
Label villi and crypts histo
Lecture Slide
What cells are in epithelium
Simple coloumnar enterocytes
Goblet cells
What cells/features are in the lamina propria
BV
Lacteal
SM
Lymphocytes
Fibroblasts (collagen)
Label Outer tunics histo
Lecture Slide
Label gastric/duodenual junction histo
Lecture Slide
Label duodenual brunners glands (submucosa)
Lecture Slide
Role of ileocecal valve large intestine
The ileocecal valve regulates the passage of materials into this expanded pouch. Collects and stores the arriving materials and begins the process of compaction
Colon - ascending, transverse, descending and sigmoid
- mucosa cell types
Smooth, no villi or plicae
Mucosal glands (crypts of Lieberkuhn) are numerous. Two cell types predominate:
* Columnar absorptive cells (similar to the enterocytes of the small intestine):
- absorb water & electrolytes
- absorb vitamins produced by bacteria (B & K)
* Goblet cells: secrete mucus for lubrication.
Label large intestine cell diagram
Lecture Slide
Lamina propria Large intestine
- cell types
-what does it lack
Contains a dense layer of collagen immediately beneath the surface epithelium; also numerous lymphatic nodules (GALT / MALT - gut- or mucosa-associated lymphatic tissue) extending down into the submucosa.
No lymphatic vessels drain the lamina propria until the level of the muscularis mucosae is reached; this may explain the relatively slow rate of metastasis from some colon cancers.
Muscularis externa Large intestine
-layers present and their purpose
Circular and longitudinal layers present. Outer longitudinal layer forms three distinct strips / bands running along the colon (teniae coli)
- Allow segments of the colon to contract independently
- Contraction pulls the intestinal tube into sac-like pockets (haustra coli)
Rectum / Anus
-purpose
what does each section of it contain
Temporary storage of faecal material; movement of material into this area triggers the urge to defecate.
Final portion = anal canal (mucosa contains longitudinal folds called anal columns).
Distal margins = transverse folds - marks boundary between columnar epithelium –> stratified squamous.
Anal sphincters = internal (smooth muscle) & external (skeletal muscle)
End of anal canal = anu
Label the large intestine (alimentary canal) anatomy
Lecture Slide
Colon histo Label
Lecture Slide
Layers of colon histo label
Lecture Slide
Colon – mucosa and submucosa Histo label
Lecture Slide
Label appendix histo AND specifics of appendix
