Histo Digestive System I & Ii

Front 1

Duodenal crypts (aka the “crypts of Lieberkuhn”) are located in the lamina propria between villi; they receive ducts from the underlying submucosal ____________.

Back 1

Brunner's glands


Front 2

______ cells are the main epithelial cell type lining the lumen of the small intestine.

Back 2

Absorptive cells

Front 3

As a Thompson rule, what epithelial tissue type will line the gut from the stomach all the way to the rectal-anal junction? What is the function of this epithelium?

Back 3

Simple columnar

Absorption and secretion!!

Front 4

As you move distally in the small intestine, you ________ the number of goblet cells.

Back 4

increase

Front 5

Besides the epithelium, describe the histology of the anus.

Back 5

The lamina propria and muscularis mucosae layers disappear distally, and the connective tissue of the submucosa changes to the dense fibrous tissue characteristic of the dermis.

The colonic smooth muscle gives way to the striated muscle of the voluntary anal sphincter.

Front 6

Describe cardiac glands: region, characteristics, type of cells.

Back 6

found in the cardiac region, have mostly mucous cells

short pits

Front 7

Describe fundic/body glands: region, characteristics, type of cells.

Back 7

the pit and gland areas are approximately equal

cells are: top third- mucous, middle third - parietal cells, lower third- chief cells

also enteroendocrine cells and stem cells located here.

Front 8

Describe pyloric glands: region, characteristics, type of cells.

Back 8

(in the pyloric region). Long pits- more mucosal cells

Front 9

Describe chief cells: location, function, what are they stimulated?

Back 9

Found in the base of the gastric glands.

-secrete pepsinogen (cleaved to pepsin in acidic lumen) and rennin,

-store cytoplasm,

-secretion is stimulated by secretin

Front 10

Describe the muscularis externa layer of the digestive tract.

Back 10

3. Muscularis Externa = inner circular, outer longitudinal smooth muscle layers; includes Auerbach’s plexus (ANS).


Front 11

Describe the serosa layer of the digestive tract.

Back 11

4. Serosa (or Adventitia for the esophagus and other retroperitoneal organs). This is the outermost layer, covering the gut tube.
Composed of a single layer of squamous epithelium (mesothelium) plus connective tissue.



Front 12

Describe the submucosa layer of the digestive tract.


Back 12

2. Submucosa = connective tissue layer which includes Meissner’s plexus (ANS)


Front 13

Describe the colon histology- the layers:


Back 13

Mucosa
1) Epithelium- simple columnar with absorptive cells and mucous cells. The crypts contain enteroendocrine cells. There are no Paneth cells.
2) Lamina propria- made of loose connective tissue, lymphoid cells, lymphoid nodules, blood vessels and lymphatics.
 Submucosa
A layer of Loose Connective Tissue with Meissner’s plexus.
 Muscularis Externa
Contains intervening Auerbach’s plexus between layers.

Front 14

Describe the function and innervation of the muscularis extrema of the small intestine.

Back 14

-function is to mix the intestinal contents and propel the contents along the
intestinal path.
-Auerbach’s plexus, (autonomic nervous system) visible sandwiched between the muscular layers

Front 15

Describe the lamina propia of the small intestine.

Back 15

-loose, delicate connective tissue and makes up the core of each
villus
-central lacteal vessel is a lymphatic capillary in the connective tissue core of the villus.
-villi have an extensive capillary supply.

Front 16

Describe the location and histology of the rectum.

Back 16

-similar in histological appearance to the colon, until about 2 cm from the anus.
-anorectal junction: crypts (glands) disappear and the epithelium becomes stratified squamous.

Front 17

Describe the structure of the intestinal brush border.

Back 17

The apical surface area of each absorptive cell
is increased by the presence of microvilli –
visible as a “brush border”.

Actin microfilaments comprise the terminal webs of
the microvilli.

Front 18

Describe the surface mucous cells of the stomach.

Back 18


The surface of the stomach is lined by surface mucous cells - simple columnar
-The mucosa beneath the pits is densely packed with simple tubular gastric glands

Front 19

Describe the three layers of the digestive tract mucosa.


Back 19

1. Mucosa = Epithelium plus underlying connective tissue (the lamina propria) plus thin layer of smooth muscle (muscularis
mucosa).

Front 20

Describe the transition in epithelium from the rectum to the anal canal.

Back 20

T transition from the lower digestive tract to skin...

-epithelium changes from simple columnar epithelium with goblet cells, through a short area of non-keratinized stratified squamous epithelium, to keratinized stratified squamous epithelium of the skin (epidermis).

Front 21

Describe the transition in the muscularis externa as you move from the upper third to middle third to lower third of the esophagus.

Back 21

upper third-skeletal m.
middle third- skeletal and smooth mm.
lower third- smooth m.

Front 22

Every gastric gland cell opens into the ________.

Back 22

gastric pit

Front 23

Fat micelles also diffuse into absorptive cells (smooth ER reforms triglycerides; these are then transported to
the Golgi, glycosylated to form chylomicrons and then absorbed via ________ in villi).

Back 23

lacteals

Front 24

Function and histology of colon.

Back 24

-Function: absorption; especially water
-Many goblet cells
-no villi
-has crypts (glandular invaginations)

Front 25

Functions of the small intestine.

Back 25

•Neutralization of chyme from stomach
•Chemical digestion
•Absorption of nutrients, water, and salts
•Immune “surveillance”

Front 26

Given that this is a fundic/body gland, name the cell types:


Back 26

mucous cells
parietal cells
chief cells

Front 27

How does a food bolus get from the esophagus to the stomach?

Back 27

A wave of muscle contraction (muscularis externa) results in the cardiac sphincter opening and allows the bolus to enter the stomach.

Front 28

How is the digestive tract innervated?

Back 28

By the autonomic nervous system,
which regulates peristalsis and secretions.

Front 29

Identify the layers of the Esophagus:



Back 29

Inner blue line - Mucosa: Epithelium (stratified squamous), Lamina propria,
Green line - Muscularis mucosa
Blue line - Submucosa: CT
Brown lines - Muscularis Externa: 2 layers are- inner circular layer, outer longitudinal.
Not shown on this slide - Adventitia

Front 30

Identify the parts of the small intestine villi:


Back 30


the light blue are the crypts of the intestinal glands
lacteals are lymphoid capillaries

Front 31

Identify the sides of this junction and the indicated features:


Back 31

gastroduodenal junction


Front 32

Identify the two sections of the stomach:


Back 32

Mucosa: epithelial invaginations form gastric glands.
Blue section - cells are light pink with central nuclei - they live in the middle portion of the gland...must be PARIETAL cells
Green section - more basophilic cells = more ER = protein production...must be CHIEF cells


Front 33

In the small intestine, the lamina propria forms the core of each villus which also contains a _______.

Back 33

lacteal

Front 34

In which part of the esophagus are glands usually present? What is their function??

Back 34

the distal part of the esophageal mucosa or submucosa

to provide lubrication for the surface

Front 35

Name the four regions and the two sphincters of the stomach:


Back 35


cardiac and pyloric sphincters

Front 36

Name these structures of the colon:


Back 36


muscularis externa

Front 37

Picture of what?


Back 37

colon, mucosa


-more goblet cells

-lamina propir is cellular!

Front 38

Recognize this structure? Where is this found?!


Back 38

ileum

Peyer's patches!!!

Front 39

The digestive tract is a muscular tube made up of a series of structures including (in order):

Back 39

oral cavity, pharynx, esophagus, stomach, small intestine (duodenum, jejunum, ileum),
large intestine (colon), appendix, rectum and anal canal.





Front 40

The digestive tract is suspended within the body cavity by a ______ through which nerves, blood vessels and lymphatics pass to and from the gut tube.

Back 40


mesentery

Front 41

The stomach epithelium is formed into numerous gastric____. The mucosa beneath this is thick and densely packed with simple tubular gastric _____.

Back 41

pits

glands

Front 42

The surface of the stomach is lined by surface ____ cells which demonstrate a simple _____ epithelium.

Back 42

mucous

columnar

Front 43

The villi of the small intestine are lined by _________ composed primarily of _________ cells, with scattered _______ cells.

Back 43

simple columnar epithelium
absorptive
goblet

villus with lacteal (lymph capillary)


Front 44

The villi of the small intestine are lined by simple columnar epithelium composed primarily of _____ cells, with scattered _______ cells.

Back 44

absorptive

goblet

Front 45

The wall of the digestive tract consists of the following tissue layers:

Back 45

1. Mucosa
2. Submucosa
3. Muscularis Externa
4. Serosa


Front 46

What is this an image of?


Back 46

ileum

Front 47

What are Brunner's glands and where are they found?

Back 47

Brunner’s glands are distinctive to the duodenum.

These mucous glands nearly fill the submucosa

-Produce a thick alkaline mucous which protects the duodenum from acidic chyme




Front 48

What are M cells?

Back 48

found in the small intestine
microfold cells are special APCs - transport antigens from lumen to tissue (GALT/ Peyer's Patches) - present antigen to T cells leading to the appearance of IgA.


Front 49

What are some examples of enteroendocrine cell products?

Back 49

CCK, gastrin


Front 50

Name the accessory organs/structures of the digestive tract?

Back 50

tongue, teeth, salivary glands, pancreas, liver, and gall bladder.

Front 51

What are the distinguishing characteristics of the ileum?

Back 51

-Peyer's patches
-villi are shorter, stubbier
-goblet cells are abundant in the epithelium


Front 52

What are the four main functions of the Digestive System?

Back 52

Mechanical (mastication) and chemical (emulsify foods) digestion
Absorption of nutrients
endocrine activity - hormones that regulate the gut motility and secretions
Waste elimination

Front 53

What are the functions of the stomach?

Back 53

chemical digestion - secretion of acid and enzymes (i.e. HCl and pepsinogen)

mechanical digestion

Front 54

What are the characteristic structures of the small intestine?

Back 54

The small intestine has both villi (protrusions) and crypts (invaginations). The lining is simple columnar
epithelium. There are modifications that increase the surface area for absorption:
- Elongation (to about 5 m);
- Plicae circularis – pleated folds of mucosa and submucosa, that are visible to the naked eye;
- Villi – projections of mucosa
- Microvilli – folds in a single cell membrane; aka “brush border”

Front 55

What are the three sections of the small intestine?

Back 55

duodenum, jejunum and ileum (in that order)

Dow Jones Index (may help you remember)

Front 56

What are the three types of gastric glands?

Back 56

cardiac glands
fundic/body glands
pyloric glands

Front 57

What are these cells and where are they found?


Back 57

parietal and chief cells
gastric gland, base and middle


Front 58

What are these cells? Where are they located?


Back 58


Parietal cells, gastric gland, middle

Front 59

What are three structures that serve to increase surface area of the digestive tract? Why increase surface area?

Back 59

villi (evaginations)
glands (invaginations)
muscularis mucosa portion of the mucosa

Increased surface area allows for increased secretion and absorption.

Front 60

What are two main examples of exocrine products of epithelial cells that line the stomach?

Back 60

HCl
pepsinogen - emulsify protein

Front 61

What clinical problems can occur in the rectum and why?

Back 61

The lamina propria has large veins (which can cause hemorrhoids when varicosities form).

Pressure inside the vein is great - causes swelling. This area is under a lot of pressure.

Front 62

hat happens when parietal cells are activated?

Back 62

They pump H+ and Cl- into the lumen

The tubulovesicles (vesicles) and canaliculus (grooves) fuse to create even more surface area



Front 63

What is an example of paracrine activity in the gut?

Back 63

When enteroendocrine products have effects on neighboring cells with specific receptors (bypassing the circulatory path)

ex. gastrin activating parietal cells

Front 64

What is another name for the single layer of squamous epithelium in the serosa?

Back 64

mesothelium

Front 65

What is found in the mucosa of the stomach?

Back 65

simple columnar epithelium and many gastric glands formed by epithelial invaginations

Front 66

What is important about the secretion of gastric intrinsic factor?

Back 66

It is involved in vitamin B12 absorption (which is needed for RBC production)

Front 67

What is the abrupt change in lining of the Esophageal/Stomach junction?


Back 67

Stratified squamous epithelium in the Esophagus
to
Simple columnar epithelium in the Stomach

Front 68

What is the adventitia of the esophagus composed of?

Back 68

CT (no mesothelium), numerous blood vessels and nerves.

Front 69

What is the appendix?

Back 69

The appendix is a diverticulum of the colon with many lymph nodules in its lamina propria.


Front 70

What is the esophagus lined with? Why?

Back 70

stratified squamous epithelium

to withstand abrasion

Front 71

What is the function of Brunner's glands?

Back 71

-Produce a thick alkaline mucous which protects the duodenum from the acidic content of chyme (from the stomach).

-optimal for intestinal enzyme activity (allowing absorption to take place), while also lubricating the intestinal walls.

Front 72

What is the function of CCK?

Back 72

CCK - target musculature of the gall bladder, receptors at acinar cells of pancreas
-when chyme enters duodenum - stimulated by CCK to secrete into duct lumen - get that detergent out! (and by that I mean BILE)

Front 73

What is the function of enteroendocrine cells?

Back 73

synthesize and release hormones, for example, gastrin, which promotes parietal cell activity.

They secrete their products basally, where they then diffuse to their targets in a paracrine fashion in the connective tissue compartment.

Front 74

What is the function of Paneth cells?

Back 74

Paneth cells are present at the bases of intestinal glands.

They secrete lysozyme and other antimicrobial molecules into the lumens of crypts.

Front 75

What is the function of secretin?

Back 75

- promotes activity of cells that line pancreatic ducts - adjacent to duodenum - duct connects the two
- promote the secretion of a bicarbonate-rich fluid

Front 76

What is the function of the brush border?

Back 76

Brush border membrane enzymes contribute to digestive breakdown with
proteolytic and disaccharidase activities.

Front 77

What is the function of the large intestine? How does this affect its histology?

Back 77

-continued absorption (especially water)
-many goblet cells
-no villi.
-has crypts (glands) that can become “engorged” in diverticulitis.



Front 78

What is the function of the muscularis externa in the digestive tract?

Back 78

Accounts for peristalsis of the gut.

Front 79

What is the mucosa of the duodenum composed of?

Back 79

villi with absorptive enterocytes (with apical microvilli) and goblet cells



Front 80

What is the name for the gross (visible) ridges of the stomach? What is their function?


Back 80

Rugae

permit expansion and contraction.

Front 81

What is the name of self-regulating cells that can live amongst the exocrine cells of the stomach?

Back 81

endocrine cells

part of the enteroendocrine system

Front 82

What is the origin of the Digestive system?

Back 82

endoderm - epithelial lining

splanchnic mesoderm - digestive tract wall (connective tissue and smooth muscle)

ectoderm- but there are nerve contributions in the form of the myenteric plexi

Front 83

What is this (both the organ and within the circle)?


Back 83

appendix

lymph follicle - sometimes referred to as a Peyer's Patch when they are found in groups

Front 84

What is this a picture of?


Back 84

apex of absorptive cell: microvilli and glycocalyx

brush border

Front 85

What is this additional feature of the small intestine?


Back 85

Paneth cells - intensely eosinophillic and at the bottom of crypts which empty into the intestinal lumen


Front 86

What is this an image of?


Back 86

Esophageal/Stomach junction

SS epithelium in the esophagus to simple columnar epithelium in the stomach

Front 87

What is this an image of?


Back 87

rectoanal junction: change in epithelium and the glands disappear

epithelium returns to stratified squamous - resist abrasion

Front 88

What is this image showing? What is their purpose?


Back 88

plicae, for increased surface area

(gross structure - visible to the eye)

Front 89

What is this image showing?


Back 89

enteroendocrine cells using a silver stain

"argentaffin cells"

Front 90

What is this image showing?


Back 90

duodenum


Front 91

What is this organ?


Back 91


stomach

note the glands along the top:

Front 92

What is this organ?


Back 92

esophagus

note the two layers of the muscularis externa and the submucosal glands

Front 93

What is this structure as a whole? What about the cells in the green circle?


Back 93

gastric gland pit



Note the simple columnar epithelium and surface mucous cells (on the surface of the stomach)

Front 94

What organ and structure is this?


Back 94

jejunum (leaf-shaped villi)

little white circles are Goblet cells!!!

Front 95

What type of cell is this?


Back 95

Parietal cell

note his tubulovesicle system:


Front 96

What type of gland is this? Which cells are shown here?

Back 96

found in deepest base of gastric glands



Front 97

Where are parietal (oxyntic) cells located and what is their function?

Back 97

Found in the middle parts of gastric glands.

HCl production and ion transport (H+, Cl-)

Secrete gastric intrinsice factor (GIF)

Have microvilli and intracellular canaliculi

Lots of mitochondria (for all that production)

Front 98

Where are the parietal (oxyntic) cells found? What is their function

Back 98

middle parts of the gastric glands

transport H+ and Cl- to lumen, secrete GIF (involved with vitamin B12), lots of mitochondria, microvilli



Front 99

Which cell is the target of gastrin, an enteroendocrine cell product?

Back 99

parietal cells

gastrin promotes their activity

Front 100

Which cell type and in which area of the digestive tract can the absorption of sodium be inhibited during episodes of severe diarrhea or Cholera?

Back 100

Absorptive cells

duodenum

-specialized for absorption of nutrients (including sodium and water) across the apical plasma membrane and export of nutrients across the basal plasma membrane.

(Normally very little sodium is eliminated. Cholera and severe diarrhea can inhibit the resorption of sodium).

Front 101

Which cells are scattered in all parts of the stomach, small intestine, and colon?

Back 101

enteroendocrine cells

Enteroendocrine cells are difficult to distinguish in routine preparations; silver stains must be used.

Front 102

Which type of cell has this surface-area-increasing system?


Back 102

Parietal cells

Front 103

Which type of cell is this special stain depicting?


Back 103

Parietal cell
note - the grooves (canaliculi)