Br Histology: Gi Tract

Front 1

What type of epithelium covers the oral cavity? What do eptithelial ridges connect to? what is the rete appuratus composed of?

Back 1

1) It is covered in most places by a stratified squamous epithelium whose epithelial ridges interdigitate with tall connective tissue papillae
(connective tissue ridges) of the subjacent connective tissue
2) The epithelial ridges and the connective tissue ridges are known collectively as the rete apparatus.

Front 2

What are the 3 sections of the lips? What type of epithelium does each have?

Back 2

1) external region = keratinized stratified squamous epithelium
2) vermillion zone = keratinized stratified squamous epithelium
3) internal region = nonkeratinized stratified squamous epithelium

Front 3

what types of glands are found in the external region of the lips?

Back 3

1) sabaceous glands
2) sweat glands
3) hair follicles

Front 4

What type of gland is present in the internal region of the lips?

Back 4

1) minor salivary glands

Front 5

What type of epithelium lines the entire palate on nasal aspect?

Back 5

pseudostratified ciliated columnar epithelium

Front 6

What type of epithelium lines the hard palate on oral side?

Back 6

1) stratified squamous parakeratinized to stratified squamous keratinized epithelium

Front 7

what type of epithelium lines the soft palate on oral side?

Back 7

nonkeratinized stratified epithelium

Front 8

Which cells produce enamel? What type of collagen does dentin contain and what cells make it? What type o

Back 8

1) ameloblasts
2) type I made by odontoblasts

Front 9

Are gingivae karatinized or nonkeratinized?

Back 9

keratinized stratified squamous epithelium

Front 10

The tongue is divided into an anterior two thirds and a posterior onethird by what?

Back 10

sulcus terminalis, whose apex ends in the foramen cecum

Front 11

what type of epithelium covers the dorsal aspect of the tongue? What type covers ventral surface?

Back 11

1) dorsal = parakeratinized
to keratinized epithelium
2) ventral = stratified squamous nonkeratinized epithelium

Front 12

Lingual papillae are located on the dorsal surface of the anterior two thirds of the tongue. What are they? What are features of each?

Back 12

a. Filiform papillae are short, narrow, highly keratinized structures lacking taste buds.
b. Fungiform papillae are mushroom-shaped structures interspersed among the filiform papillae; they contain occasional taste
buds.
c. Foliate papillae are shallow, longitudinal furrows located on the lateral aspect of the posterior region of the anterior two thirds of the tongue. Their taste buds degenerate shortly after the second year of
life.
d. Circumvallate papillae are 10 to 15 large, circular papillae, each of which is surrounded by a moat-like furrow. They are located just anterior to the sulcus terminalis and possess taste buds.

Front 13

what are taste buds? Which lingual papillae are they associated with?

Back 13

Taste buds are intraepithelial structures located on the
lateral surfaces of circumvallate papillae and the walls of
the surrounding moat-like furrows.

Front 14

what are the glands of von Ebner? what is their function?

Back 14

1) minor salivary glands that deliver
their serous secretion into the furrow surrounding each papilla,
assisting the taste buds in perceiving stimuli

Front 15

Where are the lingual tonsils located?

Back 15

located on the dorsal surface of the posterior one third of the tongue.

Front 16

What type of epithelium covers esophagous?

Back 16

stratified squamous nonkeratinized epithelium.

Front 17

What does the lamina propria of the esophagous contain? What about submucosa?

Back 17

1) the lamina propria contains mucus-secreting esophageal cardiac glands
2) the submucosa contains mucus-secreting esophageal
glands proper

Front 18

What is the muscularis mucosae of the esophagous composed of?

Back 18

a single longitudinal layer of smooth muscle.

Front 19

what does the muscularis externa of the esophagous contain in the upper, middle and lower portions?

Back 19

1) upper = skeletal muscle
2) middle = skeletal and smooth muscle
3) lower = smooth muscle

Front 20

what are the longitudinal folds of mucosa and submucosa called in the stomach called?

Back 20

1) rugae

Front 21

Where are the gastric pits deepest?

Back 21

1) shallowest at cardia and deepest at pylorus

Front 22

Describe the gastric mucosa! Does it contain goblet cells?

Back 22

(a) The simple columnar epithelium of the gastric mucosa is composed of mucinogen-producing surface lining cells (not goblet cells).
(b) The lamina propria is a loose connective tissue housing smooth muscle cells, lymphocytes, plasma cells, mast cells, and fibroblasts. It contains gastric glands
(c) The muscularis mucosae is composed of a poorly defined inner circular layer, an outer longitudinal layer, and, occasionally, an outermost circular layer of smooth muscle.

Front 23

Describe the gastric submucosa! what plexus does it house?

Back 23

(a) Is composed of dense irregular collagenous connective tissue
(b) Contains fibroblasts, mast cells, and lymphoid elements embedded in the connective tissue
(c) Houses Meissner (submucosal) plexus
(d) Possesses arterial and venous plexuses that supply and drain the vessels of the mucosa, respectively

Front 24

Describe the gastric mucosa! what plexus does it house?

Back 24

1) Is composed of three layers of smooth muscle:
a. an incomplete
inner oblique layer
b. a thick middle circular layer,
which forms the pyloric sphincter
c. an outer longitudinal
layer.
2) Auerbach myenteric plexus is located between
the middle circular and outer longitudinal smooth muscle
layers.

Front 25

Describe gastric glands! What does each gland consist of?

Back 25

1) simple branched tubular glands located in the lamina propria of the cardia, fundus, and pylorus.
2) Each gland consists of
an isthmus, which connects the gland to the base of a gastric pit, a neck, and a base.

Front 26

What is another name for parietal cells? Where are they found?

Back 26

1) oxyntic cells
2) cells of fundic glands

Front 27

What are some features of parietal cells?

Back 27

1) They possess a unique intracellular tubulovesicular system, many mitochondria, and secretory intracellular
canaliculi (deep invaginations of the apical plasma membrane) lined by microvilli

Front 28

What is another name for chief cells? where are they located in a gland? what do they secrete?

Back 28

1) zymogenic cells
2) pyramid-shaped cells located in the lower half of the gland
3) Secrete pepsinogen (a precursor of the enzyme pepsin) and the precursors of two other enzymes, rennin and lipase

Front 29

Chief cells are found in fundic glands. What are histologic features of chief cells?

Back 29

1) abundance of basally located rough endoplasmic
reticulum (RER),
2) supranuclear Golgi complex
3) many apical zymogen (secretory) granules

Front 30

Where are mucus neck cells located in gastric glands? What are histologic features?

Back 30

(a) Are located in the neck of the gland (and may be able to divide)
(b) Possess short microvilli, apical mucous granules, a prominent Golgi complex, numerous mitochondria, and some basally located
RER

Front 31

enteroendocrine cells are also known as what?

Back 31

1) APUD cells (amine precursor uptake and decarboxylation cells)
2) Possess an abundance of mitochondria and RER and a moderately well-developed Golgi complex
3) secrete only one horome

Front 32

Where are regenerative cells in the fundic glands located?

Back 32

1) primarily in the neck and isthmus
2) they replace all the epithelial cells of the gland, gastric pit,
and luminal surface

Front 33

Cardiac and pyloric glands are different from fundic glands how?

Back 33

they are coiled tubular mucus-secreting glands and lack chief cell

Front 34

Gastrin is released from what cells? What other molecules have same function?

Back 34

1) released by enteroendocrine cells in the gastric and duodenal
mucosa, together with histamine and acetylcholine, stimulates
HCl secretion

Front 35

Where is somatostatin produced? what is its function?

Back 35

produced by enteroendocrine cells of the pylorus and duodenum, inhibits the release of gastrin and thus indirectly inhibits HCl secretion.

Front 36

What produces urogastrone? what is its function?

Back 36

1) produced by Brunner glands of the duodenum, and
gastric inhibitory peptide, produced by enteroendocrine cells in the small intestine, directly inhibit HCl secretion.

Front 37

What luminal surface structures does the small intestine have?

Back 37

a. Plicae circulares (valves of Kerckring) are permanent spiral
folds of the mucosa and submucosa that are present in the distal half of the duodenum, the entire jejunum, and proximal half of the ileum. Plicae circulares increase the surface area two-fold to
three-fold.
b. Intestinal villi are permanent evaginations that possess,
in their connective tissue core (lamina propria), numerous
plasma cells and lymphocytes, fibroblasts, mast cells, smooth muscle cells, capillary loops, and a single lacteal (blind-ended lymphatic
capillary). Villi increase the surface area ten-fold.
c. Microvilli of the apical surface of the epithelial cells of each villus possess actin filaments that interact with myosin filaments in the terminal
web. Microvilli increase the surface area about twentyfold.

Front 38

What type of epithelium does the small intestine have?

Back 38

simple columnar, composed of goblet cells, surface absorptive cells, and some neuroendocrine cells

Front 39

What are features of the goblet cells in the small intestine? How do there numbers change from duodenum to ileum

Back 39

(a) Are unicellular glands that produce mucinogen, which accumulates in membrane-bounded granules, distending the apical region (theca) of the cell. After being released, mucinogen becomes hydrated and is thus converted to mucin, a thick, viscous substance that acts as a protective coating of
the epithelial lining of the lumen.
(b) Have their nucleus and other organelles in the basal region (stem) of the cell
(c) Increase in number from the duodenum to the ileum

Front 40

How are the surface absorptive cells of the small intestine characterized? what type of junction is present?

Back 40

(a) Are tall columnar cells with numerous mitochondria, smooth and RER, and a Golgi complex
(b) Possess a layer of closely packed microvilli (striated border) on their free apical surface
(c) Have a glycocalyx, which overlies the microvilli and binds
various enzymes (disaccharidases and dipeptidases)
(d) Have well-developed tight junctions and zonula adherens

Front 41

What does the lamina propria contain in the small intestine?

Back 41

(1) Occupies the cores of the villi and the interstices between the numerous glands (crypts) of Lieberkiihn
(2) Consists of loose connective tissue with lymphoid cells, fibroblasts, mast cells, smooth muscle cells, nerve endings, and lymphoid nodules
(3) Also contains lacteals (blind-ended lymphatic vessels) and capillary loops

Front 42

Describe the crypts of lieberkuhn? What cell types do they have?

Back 42

1) simple tubular glands that extend from the intervillous spaces to the muscularis mucosae of the intestine.
2) They are composed of goblet cells (and oligomucous cells), columnar cells (similar to surface absorptive cells), enteroendocrine cells, regenerative cells, and Paneth cells

Front 43

Where are paneth cells located? what do they secrete? What are histologic features?

Back 43

1) located at the base of the crypts of Lieberkiihn, are pyramid-shaped cells that secrete the antibacterial enzyme lysozyme stored in large, apical, membrane-bounded secretory granules.
2) These cells also
display extensive RER (basally), a large supranuclear
Golgi complex, and many mitochondria.

Front 44

Where are the regenerative cells of the crypts of Lieberkuhn located? What are there histologic features?

Back 44

1) located in the basal half of the crypts of Lieberkiihn, are thin, tall, columnar stem cells that divide to replace themselves and the other types of epithelial cells.

Front 45

how do lymph nodules progress in the small intestine? What are features?

Back 45

1) usually small and solitary in the lamina propria of the duodenum and jejunum
2) They increase in size and number in the ileum, where they form large contiguous aggregates, known as Peyer patches, which extend
through the muscularis mucosae into the submucosa.

Front 46

What are features and function of M cells?

Back 46

1) highly specialized, have an unusual shape, and lie in the epithelium over lymphoid nodules and Peyer patches.
2) They are derived from undifferentiated cells of the crypts of Lieberkiihn.
3) They sample antigens as well as bacteria, viruses, and parasitic microorganisms
4) The endocytosed particles are conveyed, via transcytosis, to macrophages and lymphocytes that lie in the infoldings of the basal plasmalemma of M cells.
5) These macrophages and the B and T lymphocytes are actually located in the lamina propria.

Front 47

After M cells stimulate B cells to produce IgA what happens?

Back 47

1) Plasma cells manufacture IgA, some of which is taken
up by and bound to secretory protein within the epithelial
cells and is transported across the intestinal epithelium
(transcytosis) to the glycocalyx, where it remains as an immunologic defense against bacteria and antigens in the lumen. Much of the IgA enters blood vessels, and goes to the liver, where it is picked up by hepatocytes to be secreted as part of bile.
2) From the liver, IgA enters the gall bladder to be released into the lumen of the duodenum

Front 48

What is the muscularis mucosae of the small intestine composed of?

Back 48

an inner circular and an
outer longitudinal layer of smooth muscle.

Front 49

What does the submucosa of the small intestine contain? what hormones are produced from the glands there?

Back 49

a. Consists of fibroelastic connective tissue containing blood and lymphatic vessels, nerve fibers, and Meissner plexus
b. Also houses Brunner glands, which are present only in the duodenum.
c. These glands produce an alkaline fluid and urogastrone.
The former protects the duodenal epithelium from the acidic chyme; the latter is a polypeptide hormone that enhances epithelial cell division
and inhibits gastric HCl production.

Front 50

What is the muscularis externa of the small intestine is composed of? What is formed and contained within the muscularis externa?

Back 50

1) an inner circular and an outer longitudinal layer
2) The inner layer participates in the formation of the ileocecal
sphincter
3) Auerbach (myenteric) plexus is housed between the two
layers.

Front 51

What is the function of the large intestine?

Back 51

absorption of electrolytes, fluids, and gases

Front 52

What does the mucosa of the cecum and colon lack?

Back 52

lacks villi and possesses no
specialized folds.

Front 53

What are features of the mucosa of the cecum and colon?

Back 53

(1) The epithelium of the mucosa of the cecum and colon is simple columnar with numerous goblet cells, surface absorptive cells, and occasional DNES cells.
(2) The lamina propria is similar to that of the small intestine, possessing
lymphoid nodules, blood and lymph vessels, and closely
EP packed crypts of Lieberkuhn, which lack Paneth cells.
(3) The muscularis mucosae consists of an inner circular and outer longitudinal layer of smooth muscle cells.

Front 54

What is the submucosa of the cecum and colon composed of? What does it contain?

Back 54

1) composed of fibroelastic
connective tissue
2) It contains blood and lymphatic vessels, nerves, and Meissner (submucosal) plexus.

Front 55

What is the muscularis externa of the cecum and colon composed of? what nerve plexus does it contain?

Back 55

1) The muscularis externa of the cecum and colon is composed of an inner circular and a modified outer longitudinal layer of smooth
muscle.
2) The outer layer is gathered into three flat, longitudinal ribbons of smooth muscle that form the teniae coli. When continuously contracted, the teniae coli form sacculations of the wall known as haustra coli.
3) Auerbach (myenteric) plexus is housed between the
two layers of smooth muscle.

Front 56

What are features of the anal mucosa?

Back 56

longitudinal folds called anal columns (or rectal columns of Morgagni), which join each other to form anal valves. The regions between adjacent valves are known as anal
sinuses

Front 57

what type of epithelium is found in the anal canal?

Back 57

(a) Is simple columnar changing to simple cuboidal proximal to the anal valves
(b) Is stratified squamous nonkeratinized distal to the anal
valves
(c) Changes to stratified squamous keratinized (epidermis) at the anus

Front 58

What is the muscularis mucosae composed of in the anal canal?

Back 58

consists of an inner circular and an
outer longitudinal layer of smooth muscle, both of which terminate
at the anal valves.

Front 59

What is the anal muscularis mucosa composed of? What is formed from internal layer?

Back 59

composed of an inner circular and
an outer longitudinal layer of smooth muscle. The inner circular layer forms the internal anal sphincter.

Front 60

What is the mucosa of the appendix composed of?

Back 60

The epithelium is simple columnar and contains surface
columnar cells and goblet cells.

Front 61

What does the lamina propria of the appendix contain?

Back 61

1) displays numerous lymphoid nodules (capped by M cells) and lymphoid cells. It does not form villi but possesses shallow crypts of Lieberkiihn with some goblet cells,
surface columnar cells, regenerative cells, occasional Paneth cells, and numerous enteroendocrine cells

Front 62

Where does the absorption of lipid primarily occur?

Back 62

1) duodenum
2) upper jejunum

Front 63

In what organelle are chylomicrons produced?

Back 63

golgi complex

Front 64

Which cell produces CCK and where is cell found? What is function?

Back 64

1) I cell
2) small intestine
3) Stimulates release of pancreatic enzymes and contraction of gall bladder (with release of bile)

Front 65

What cell type produces GIP and where in GI? What is function?

Back 65

1) K cells
2) small intestine
3) Inhibits gastric hydrochloric
acid (HCl) secretion

Front 66

Which cells produce gastrin and where in GI? what is function?

Back 66

1) G cells
2) pylorus and duodenum
3) Stimulates gastric secretion of
HCl and pepsinogen

Front 67

Which cells produce glicentin? where in GI tract? What is function?

Back 67

1) GL cells
2) stomach through colon
3) Stimulates hepatic glycogenolysis

Front 68

Which cells in GI tract produce glucagon? Where?

Back 68

1) A cells
2) stomach and duodenum

Front 69

Which cells produce motlin? Where are they located? What is function?

Back 69

1) Mo cells
2) small intestine
3) increase GI motility

Front 70

Which cells produce neurotensin? Where? What is function?

Back 70

1) N cells
2) small intestine
3) inhibits gut motility, stimulates blood flow to ileum

Front 71

Which cells produce secretin? where in GI? what is function?

Back 71

1) S cells
2) small intestine
3) Stimulates bicarbonate secretion by pancreas and biliary tract

Front 72

Which cells in GI secrete serotonin and substance P? where in GI? what is function?

Back 72

1) EC cells
2) stomach through colon
3) increase gut motility

Front 73

Which cells in GI produce somatostatin? where? what is function?

Back 73

1) D cells
2) pylorus and duodenum
3) inhibits nearby enteroendocrine cells

Front 74

What cells secrete VIP? Where in GI? what is function?

Back 74

1) VIP cells
2) stomach through colon
3) Increases gut motility, stimulates intestinal ion and water secretion