Like this study set? Create a free account to save it.

Sign up for an account

Already have a Quizlet account? .

Create an account

4 Major Layers of GI Tract
-->Mucosa, Submucosa, Muscularis Externa/Propria, Adventitia/Serosa

Example of Protective (Above)(Ex. Stratisfied Squamous Ep.; Esophagus) & Secretatory (Below)(Stomach)

Example of Absorptive (Above)(Ex. Simple Columnar Epithelium; SI) and Aborptive/Protective (Below)(Ex. Simple Columnar Epithelium; Reabsorptive of water; LI)

Simple Columnar Epthelium
-->Goblet Cells
-->Microvilli covering surface of the intestinal villi

Lamina Propria
-->Microvilli on Apical Surface of simple columnar epithelium
-->Plasma Cells in lamina propria

Deep Layers Layers of GI Tract
-->Messiner's Ganglion ("Submucosal Ganglion")(PG)

Muscularirs Mucosa (2 Layers: Circular & Longitudinal)

Meissner's Ganglion/Submucosa Plexus
-->Eccentric Nucleus

Myentric/Auerbach's Ganglion betwn. the 2 Layers of Muscularis Externa
-->The plexus (ganglion & nerve)

Aurbach's Plexus in Muscularis Externa
1) Serosa (Corvered by 1 layer of squamous epithelium)

Esophagus (Oropharynx to Stomach)
-->Star Shape Lumen
-->Observe Difference betwn Circular & Longitudinal Muscle

Middle 1/3 of Esophagus (smooth & skeletal muscle)

Esophageal Mucosa

Esophageal Mucosa & Submucosa
-->**Contain Esophageal Gland Proper in Submucosa**

Mucosa of Esophague (Srat. Squamous non-ker. epithelium)
-->Lamina Propria underneath epithelium

Mucous gland in the Submucosa of Esophagus ("Esophageal Gland Proper")
-->Mucus cell nuclei are condensed & flattened against basement membrane

Gastro-esophageal Junction
-->See transition from stratisfied squamous epithelium (esophagus on far right) to simple columnar epithelium of the stomach (left)

Gastro-esophageal Junction

Upper 1/3 of Esophagus
-->Esophageal Gland Proper of Submucosa
-->Muscularis externa contains skeletal muscle

Skeletal Muscle of Muscularis Mucosae in upper 1/3 of esophagus

Lower 1/3 of Esophagus
-->Smooth muscle in outer muscularis externa

Gastro-Esophageal Juntion =

Glands in GE Junction
**CARDIAC GLANDS in lamina propria**(Secrete products in gastric pits)
***ESOPHAGEAL GLAND PROPER in submucosa of esophagus

Cardia of Stomach
-->Shallow gastric pit & short gastric gland
-->See the **CARDIAC GLANDS** in the lamina propria (Branching and coiled)

Cardiac Gland leading in from a gastric pit (upper right)
-->Cardiac gland produces mucus by **Surface mucus cell**
--Mucus prevents HCl from destroying the epithelium that surrounds the stomach

Mucosal Surface Of The Stomach
-->Arrows on the left represents the openings of glands from cardia, corpus (body), or pylorus

Body of the stomach
-->Same histologically as the fundus
-->Short & shallow gastric pit (GP)
-->Contains long, tubular gland that occupies entire length of lamina propria
-->***STOMACH contains 3 layers in muscularis externa (inner oblique, inner circular, & outer longitudinal)

3 Layers of Muscularis Externa of the stomach

Junction betwn. cardia & fundus (Cardiac vs. Fundic Gland)

Fundus or Corpus of Stomach
-->Surface Mucus cells (upper right) & parietal cells (large, eosinophillic cytoplasm; centrally placed nucleus, & fried-egg appearence ~oligodendrocytes)
-->Chief cells seen on bottom near bottom with granules of pepsin (basophilic due to high ribosome content)

Fundus & Corpus of Stomach

Gastric Cells of Gastric Gland of fundus/body
-->Surrounds a gastic pit (secretes mucus on the surface)

Surface mucous cells & Neck mucous cells

Parietal & Chief Cells

Schematic of Parietal Cell

Parietal Cell on EM
-->High amounts of mitochondria
-->Intracellular Caniculi ("Inside the cell")
-->Tubulovesicular System

Schematic of Chief Cell

Chief Cell on EM
-->Zymogen Granules
-->Rough ER
-->Supranuclear Golgi Apparatus

Base of Gastric Gland
**Contains Neuroendocrine Cells**
-->Also see parietal cell & gastric cell (Pc; peptic cell)

Pyloric Stomach
-->Contains DEEP gastric pits that run ~1/3 the length of the lamina propria
-->The second half becomes coiled (Gastric Gland) & contains "G" Cells that STIMULATE chief cells to produce HCl

Overview of Pylorus of the stomach

Pyloric Glands in the lamina propria

Pyloric Glands in the lamina propria

Gastroduodenal Junction
-->Contains Pyloric sphincter (PS), glandular mucosa of the stomach (S), Mucosa of Duodenum (D), Brunners Gland (B), and 2 layers of muscularis externa (CM & LM; ***no oblique layer)
-->***Brunner's Gland in the mucus secreting glands in SUBMUCOSA OF THE DUODENUM

Small Intestine
-->Distinct characteristics
1)Villi on outside surface cover the transverse folds (plicae circulares)
-->Microvilli on top of villi
2)**Brunner's Glands in Submucosea ALWAYS indicate that you are in DUODENUM

-->Contains Brunner's Glands in submucosa

Intestinal Villi & Crypts of SI
-->Lined by simple columnar epithelium
-->Other important cell types (some not visible in picture):
1)Goblet cells
2)Paneth cells (***Prominent, eosinophilic apical granuels; fxn. is defensive)
3)Neuroendocrine cells
4)Stem Cells (***At base of the crypts)

Intestinal Villi of SI
Note: Both mucus & glcocalyx both protect the epithelium against AUTODIGESTION

Brunners glands in subucosa of SI

***Crypts of Lieberkuhn of the duodenum

Intestinal Villi ("Fingerlike projections")
-->Also contain lymph capillaries in the CORE OF VILLUS

Central Lacteal in the Intestinal Villi
-->Lacteal represent a blind-ended lymphatic capillary that may contain smooth muscle that is NOT APART OF MUSCULARIS MUCOSAE
1)Major fxn is to bring lipid-absorbed substances from the lumen into the lacteal

Intestinal Villi
-->Can be variable in shape
-->Lacteal on the far right contains a CENTRAL LACTEAL

Intestinal Villus of rat
-->Illustrates presense of absorped lipids
-->Black stain represents high amount of lipid in enterocyte cytoplams & chylomicrons (lipoprotein droplets)
1)Chylomicrons will use the central lacteal to enter systemic circulation

Topagraphy of Duodenum

Topagraphy of Jejunum

Topagraphy of Illeum
-->High aggregation of lymphoid is seen as PEYER'S PATCHES

Villous of Jejunum
-->Contains High number of GOBLET CELLS

Lymphocytes Aggregation In Jejunum

-->Contains valves of Kerckring & Peyer's Patches

Enterocyes (*See Wheaters for bigger image)
(1)Features of enterocytes (upper pic.)
-->Large # of microvilli that represent the BRUSH BORDER microscopically
-->Mitochondria (M) in high amounts
-->Intercellular Clefts (IC) & basement membrane (BM) represent layers chylomicrons must pass to enter core of the villus
->Lymphocytes found in the intercellular clefts in betwn. enterocytes
(2)Features of enterocytes (lower pic.)
-->Prominent GYCOCALYX on enterocyte microvilli
-->Terminal web sen at bottom of microfilament cytoskeletion of microvilli (Def:A dense meshwork of spectrin and myosin molecules located at the base of a microvillus to which the bundle of actin microfilaments that make up the core of the microvillus is anchored)

Basal Aspect of 2 Enterocytes
-->Contains intracellular cleft betwn 2 enterocyte cell
-->Endothelium of central lacteal

Goblet Cell

Crypts of Lieberkuhn of SI
-->Contains **PANETH CELLS**
1)Intensly eosinophilic apical cytoplasmic granules
2)Granules contain **DEFENSINS**(antimicrobial peptides) and **LYSOZYME & PHOSPHOLIPASE A (protective enzymes) that serve as the first line of defense against any pathogens that survive passage through the stomach (i.e. "Natural form of antibiotic")

Capillary Network of the Intestinal Villi
**Most of absorbed food products enter the capillaries & pass via the portal vein to the liver EXCEPT TRIGLYCERIDES**

Prominent Peyers Patches of lymph nodules in the lamina propria of Ileum

Aurbach's Plexux in SI
-->In betwn inner circular & outer longitudinal SM

Ileocacecal Junction
-->See transition of lining of IC Valve from small intestines (villiform patters; S) to glandular form in the LI *L)
-->Ileocecal valve consists of a thickened extension of muscularis propria (M) that provides robust support for the mucosa
-->Lymphoid tissue (lymphoid tissue (Ly) in form of large Peyer's Patches are found in the mucosa

Coeliac Disease (Coeliac Sprue or Gluten Enteropathy)
-->Caused by an immunologic response to gluten (component of wheat, oats, barley, rye)
-->Individuals with condition present with symptoms of malaborption (weight loss, steatorrhoea, anemia, vitamin deficiences) b/c fewer NUTRIENTS are able to be absorbed
->***Biopses of small bowel for diagnosis will displayL
1)Loss of normal intestinal villi
2)Incr. of lymphocytes & plasma cells in lamina propria

Large Intestine
-->Contains absorptive cells & mucus-secreating goblet cells arranged in CRYPTS (closely packed straight tubular glands) that extend into the MUSCULARIS MUCOSEA
***Contains NO VILLI
-->Mucosa forms longitudinal folds (COLUMNS OF MORGANI) above anal valves
-->Muscularis Mucosae rhythmically contract to prevent clogging of the glands & enhance the expulsion of mucus

Muscular wall of large intestine
-->**Can see tenia coli in the longitudinal layer of muscularis externa (**Not seen in the rectum)

Mucosa of Colon
-->Arrows point to opening of crypts of Leiberkuhn (straight, unbranched tubular glands
-->Lamina propria seen IN BETWEEN the glands
-->Opening of the crypts of Luberkuhn makes the feces MORE COMPACT via lubrication (feces is easier to move)

Absorptive & Goblet Cells of the Colon

Crypts of Colon containing many goblet cells

Pictures of colon
-->Alcian blue method stains goblet cell cell mucus greenish blue vs poorly stained absorptive
1)Goblet cells encompass BASE OF GLAND
2)Absorptive cell found mostly in the luminal surface

Colrectal Adenocarcinoma
-->Affect older patients 50-60 yrs. old
-->Is a *malignant tumours arising in the glandular epithelium

-->Structure similar to that of large intestine
-->Contain large masses of lymphoid tissue in mucosa & submucosa (*Esp. in the young)
-->High # of lymphocytes in lamina propria
1)Lymphoid tissue forms follicles that contain germinal centers (***Invested by a simple epithelium of M Cells; M Cells facilitate the sampling of antigen in the lumen)
-->Less packed mucosal glands than in large intestine

Recto-anal Junction
-->in anus you see sebaceous and LARGE apocrine glands

-->Contains large apocrine glands and **complete muscularis externa**(anal sphincter

Topagaphy of anal canal

Micofold (M) Cells
-->Epithelial cells that overlie Peyer's patches & other large lymphatic nodules

M Cells are APC's b/c they contain both MHC Class I & MHC Class II (**ERORR ON SLIDE**)

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions and try again


Reload the page to try again!


Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

Voice Recording