04a: GI Tract Histology Flashcards by Nuna H

Simple tubular invaginations of the surface epithelium of stomach.

Gastric pits

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List the 5 cell types found in gastric glands. Star the ones you have to ID.

Parietal cells*
Chief cells*
Mucus “neck” cells
Stem cells
Eneteroendocrine cells (EEC)

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Parietal cells are source of (X). They’re notably (basophilic/eosinophilic).

X = HCl and gastric intrinsic factor

Eosinophilic

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Chief cells are source of (X). They’re notably (basophilic/eosinophilic).

X = pepsinogen

Basophilic (due to RER, ribosomes)

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Which two features specifically characterize the

small intestine?

Intestinal villi and plicae circulares

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Intestinal villi are folds of (X) tissue layer that extend into lumen.

X = lamina propria

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Plicae circulares are folds of (X) tissue layer. They’re similar to (Y) structure, but (do/don’t) flatten with distension of lumen.

X = submucosa
Y = rugae
Don’t

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The wall of small/large intestine itself has tubular invaginations called (X). How far/deep do these extend?

X = intestinal crypts (crypts of Lieberkuhn)

To muscularis mucosae

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(X) cells are the most frequent in the epithelium of the duodenum, decreasing in frequency in the direction of the large intestine.

X = enterocytes (simple columnar absorptive cells)

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(X) cells are least frequent in the duodenum, and increase in frequency toward the large intestine and anal canal. What does their cytoplasm contain?

X = goblet

Mucinogen

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(X) is the exocrine cell of small intestine. They have (basophilic/eosinophilic) granules that secrete (Y).

X = paneth
Eosinophilic
Y = lysozyme (anti-bac for protection)

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Colon has three grossly visible bands of thickened (X) tissue
layer, known as taeniae coli.

X = muscularis externa (outer longitudinal layer)

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Which embryonic tissue gives rise to epithelium lining of digestive system?

Endoderm

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Which embryonic tissue gives rise to glands of digestive system?

Endoderm

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Embryology: epithelial tube is surrounded by (X) tissue.

X = splanchnic mesoderm

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Which embryonic tissue gives rise to muscle and CT of digestive system?

Splanchnic mesoderm

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Which embryonic tissue gives rise to blood vessels of digestive system?

Splanchnic mesoderm

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Which embryonic tissue gives rise to visceral peritoneum components of digestive system?

Splanchnic mesoderm

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Which embryonic tissue gives rise to parietal peritoneum components of digestive system?

Somatic mersoderm

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Embryology: Pharyngeal portion of foregut extends from (X) to (Y).

X = buccopharyngeal membrane
Y = respiratory diverticulum

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Embryology: Foregut “proper” begins (rostral/caudal) to pharyngeal tube and extends until (X).

Caudal

X = superior duodenum (superior to ampulla of pancreatic duct)

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Embryology: midgut extends from (X) to (Y).

X = inferior to bile/pancreatic duct in duodenum
Y = Jxn of right 2/3 and left 1/3 of transverse colon

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Embryology: hindgut extends from (X) to (Y).

X = Left 1/3 of transverse colon
Y = cloacal membrane

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Embryology: Stomach rotates (X) degrees (clockwise/counter-clockwise).

X = 90

Clockwise

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List the main characteristic of pyloric stenosis.

Inner circular layer of muscularis externa hypertrophies

Pyloric stenosis is most common in (newborns/adults/elderly) and (males/females).

Newborns (presents 3-5 days post-partem) | Males

T/F: Ultrasound provides accurate diagnosis of pyloric stenosis in over 90% of cases.

True

During development, physiological herniation occurs when intestinal loops enter (X). This occurs during weeks (Y) of development. What's the reason?

``` X = extraembryonic cavity Y = 6-10 ``` Liver growing

If intestines fail to return to body cavity following phase of physiological herniation, which malformation occurs?

Omphalocele

Protrusion of viscera into amniotic cavity due to abnormal closure of body wall is called:

Gastrochisis

(Omphalocele/gastrochisis) presents with intestines covered in amnion.

Omphalocele

Usually the reason gastrochisis occurs is (excess/lack) of (X).

Lack | X = vascularization (thus, proliferation; not enough tissue mass for proper fusion/folding)

The pectinate line is found within (X) structure. It marks the junction between which two tissue types?

X = anal canal Endoderm (superior 2/3) and ectoderm (inferior 1/3)

Pectinate line represents site where (X) embryological structure was.

X = cloacal membrane

Most common congenital defect of GI system is (X), which is due to (Y).

``` X = Meckel's (ileal) diverticulum Y = persistence of vitelline duct ```

T/F: Meckel's diverticulum typically presents with persistent vomiting and distended bowel.

False - typically symptomless

Meckel's diverticulum may present with serious symptoms if (X) is present.

X = ectopic gastric/pancreatic mucosa (secretes acid)

Serosa, by definition, is composed of which components?

Mesothelium and underlying CT

(Serosa/adventitia) covers esophagus.

Adventitia until esophagus passes diaphragm (then, serosa)

The prevalent history of esophageal tumors involves which cell type? Tumors involved the (adventital/serosal) part of esophagus have a poor prognosis.

Squamous cell; Adventitial (spread easier)

List the two types of glands found in esophagus. Star the mucin-secreting ones.

1. Esophageal glands proper* | 2. Esophageal cardiac glands*

Esophageal glands proper are found in (X) tissue layer and secrete (Y) for which function?

``` X = submucosa Y = mucus ``` lubricate wall

Esophageal cardiac glands are found in (X) tissue layer and secrete (Y) for which function?

``` X = lamina propria Y = mucus ``` Protective (from regurgitated gastric contents)

T/F: Esophageal cardiac glands are purely mucus.

True

UES formed by (X) muscle. LES formed by (Y) muscle.

``` X = cricopharyngeus Y = inner circular layer of muscularis externa ```

Function of UES is to prevent (X). Function of LES is to prevent (Y).

``` X = reflux and air from entering esophagus Y = reflux from stomach into esophagus ```

List the three components of the anti-reflux barriers.

1. LES 2. Angle of His 3. Diaphragm

T/F: Main barrier to reflux of gastric contents is diaphragm.

False - LES

"(X) esophagus" can result from chronic GERD. Describe what's going on.

X = Barrett Metaplasia (esophagus epithelium becomes simple columnar instead of SSNK)

List the histological findings of Barrett esophagus.

1. Pink epithelium 2. Goblet cells 3. Gastric surface mucus cells

You'd expect to find (1/2/3) different cell types lining stomach lumen. List them.

1; | Surface mucous cell (simple columnar)

T/F: Surface mucous cells line entire surface of stomach as well as the gastric pits.

True

T/F: Surface mucous cells aren't found in gastric glands.

False

In the stomach, the "isthmus" marks transition from (X), containing purely surface mucous cells, to (Y), containing variety of cell types.

``` X = gastric pit Y = gastric gland ```

Parietal cells are (X)-shaped cells that are primarily found in (Y) region of gastric (pit/gland)

X = triangular Y = neck Gland

T/F: EECs in stomach are primarily located toward stomach lumen in gastric glands.

False - typically deeper/further from lumen

Surface mucous cells are renewed every (X) (hours/days/weeks). The stem cells are located near (Y) region of gastric glands.

``` X = 3-5 days Y = isthmus ```

Which glands would you expect to find in submucosa of stomach?

None!

T/F: Parietal and chief cells are found in gastric glands throughout entire stomach.

False! Only fundic/gastric region (and maybe some in cardiac region)

T/F: Mucus neck cells, EECs, and stem cells are found in gastric glands throughout entire stomach.

True

List the three specializations/modifications of small intestine that increase surface area.

1. Intestinal villi 2. Microvilli 3. Plicae circularis

Core of microvillus is composed of (X), which extend into apical aspect and inset into (Y).

``` X = vertical microfilaments Y = horizontal microfilaments ```

Epithelial cells of small intestine are bound to one another via (X). This consists of which three structures?

X = Junctional complexes 1. Zonula occludens (tight junctions) 2. Zonula adherens 3. Macula adherens (Desmosome)

The junctional complex is seen on (EM/LM) and corresponds to (X) structure on (EM/LM).

EM; X = terminal bar LM

(X) cells in small intestine function in absorption as well as secretion of water, electrolytes, and (Y).

``` X = enterocytes Y = glycoprotein enzymes (form glycocalyx) ```

The small intestine stem cells are located near (X) region of intestinal glands.

X = base of crypt

T/F: M cells are APCs.

False - antigen-transporting cells

(X) are blind-ended lymphatic capillaries in (Y) part of GI tract.

``` X = central lacteals Y = small intestine ```

A number of steps are involved in lacteal uptake of fat. (X) cells absorb (TAG/MAG and FA) from lumen. The fat is exocytosed to lacteal in which form?

X = enterocytes MAG and FA Re-synthesized TAG, in chylomicron

What's the function of Brunner's glands in (mucosa/submucosa/muscularis) of (X) anyway?

Submucosa X = duodenum Protect epithelium (bring intestinal contents to optimal pH)

You'd find Peyer's patches in (X) tissue layer of (Y) structure.

``` X = lamina propria and submucosa Y = ileum ```

List the three basic functions of the colon.

1. Reabsorption of water/electrolytes 2. Propel undigested food/waste 3. Protect epithelium from abrasion

Large intestine has uniquely (thin/thick) CT layer in lamina propria. This functions to regulate (X).

Thick; | X = water/Na absorption and transport to capillaries

There's an extensive development of lymph tissue in (stomach/small intestine/large intestine) lamina propria. But the lymphatic vessels are found in (X) tissue level.

Large intestine | X = muscularis mucosae

Lymph nodules of appendix are found in (mucosa/submucosa/muscularis).

Mucosa

(Upper/lower) region of (rectum/anal canal) has transverse folds.

Upper; rectum

Anal canal is about (X) long and divided into which zones?

X = 4 cm 1. Colorectal zone 2. Anal transitional zone 3. Squamous zone

Epithelium transitions: from colon until (X), epithelium is which type? Then what does it transition to?

X = proximal anal canal; SSNKE, then SSKE