Gibneys + Dreyfus. - Histo Of Alimentary Canal

Question 1

How does The muscularis externa change depending on which part of the esophagus you are in?

Answer 1

Upper - all skeletal
Middle - half skeletal half smooth
Lower - all smooth

Question 2

What kind of epithelium in the esophagus?

Answer 2

Stratified squamous

Question 3

What type of epithelium does the stomach have?

Answer 3

Simple columnar with no goblet cells and villi. 3 layers of muscularis externa as opposed to the esophagus that had 2.
- Has pits and glands

Question 4

What is the location called that we switch from stratified squamous to simple columnar?

Answer 4

Gastoesophageal junction

Question 5

Cardiac of the stomach

Answer 5

• mostly mucous secreting glands
• glands are tubular, coiled, and perhaps branched
• 1:1 ratio of Piti to gland

Question 6

Fundus of the stomach

Answer 6

• most colorful area due to staining o chief and parietal cells.
• 1:3 ratio of pit to glands

Question 7

WHAT COLOR DO parietal cells stain? Chief cells?

Answer 7

Parietal - red stain

Chief - blue

Question 8

What does a chief cell secrete?

Answer 8

Pepsinogen

Question 9

What does an Inactive parietal cell secrete?

Answer 9

HCl, HCO3-, IF

- lots of mitochondria and tubules and vesicles termed the “membrane reserves”

Question 10

Pyloric stomach

Answer 10

• mostly mucous secreting glands
• no chief or parietal cells
• glands are branched, coiled tubular glands with a wide lumen
• 3:1 pit to gland ratio.

Question 11

What part of the stomach can you find the chief and parietal cells?

Answer 11

Fundus

Question 12

Gastroduodenal junction

Answer 12

Stomach - no goblet cells
Duodenum - yes goblet cells

Stomach - no villi
Duodenum - yes villi

Stomach - 3 layers of muscularis externa
Duodenum - 2 layers of muscularis externa

Question 13

Histological features of the SI

Answer 13

• goblet cells
• villi
• simple columnar epithelium
• crypts of Lieberkuhn

Question 14

Plicae circularis

Answer 14

Sub mucosal folds in the intestines that increase surface area

Question 15

KEy feature of the duodenum

Answer 15

Brunners glands - produce alkaline secretion to neutralize acidity of stomach.
- in mucosal layer

Question 16

Key feature of the jejunum

Answer 16

Long villi

Question 17

Lacteals

Answer 17

Found in the villi.

- Processing of lipids into chylomicrons occurs in the enterocytes and is then discharged into the lacteals.

Question 18

Key feature of the Ileum

Answer 18

Peyers Patches - lymphoid nodules

- short and fat villi

Question 19

M-cell

Answer 19

Specialized epithelial cell that takes up antigens which are then transported by transcytosis to present immunocompetent B lymphocytes.

• Essentially responsible for getting rid of invading microbes/pathogens in the ileum.
• found in the peters patches.

Question 20

DNES cells

Answer 20

• found throughout the digestive system
• secretes hormones such as gastrin, glucagon, somatostatin, and motility.
• secretes these hormones directly into the blood circulation.
• influences motility and digestion
• can be open or closed

Question 21

Paneth cells

Answer 21

Located at the bottom of crypts. They monitor microbial flora.
- they produce lysozyme, tumor necrosis factor-alpha, and defensins/cryptidins

Question 22

4 layers of the GI tract

Answer 22

Mucosa - epithelium, lamina, propria, muscularis mucosae
Sub mucosa
Muscularis externa - Circular + Longitudinal
(Serosa)
- More Sweet Chili Langert

Question 23

Key features of the colon

Answer 23

No villi
Increase in goblet cells
Taenia coli

Question 24

Plicae semilunar

Answer 24

Submucoal fold in the large intestine

Question 25

Appendix

Answer 25

Same epithelial lining as the colon Differs. From colon in that it has a uniform layer of longitudinal muscle in the muscularis externa Key feature - many lymph nodules with germinal centers

Question 26

Recto-anal junction

Answer 26

Simple columnar with goblet cells --> stratified squamous epithelium

Question 27

What is a key feature of the esophagus

Answer 27

Mucous glands are found in the lamina propria or th submucosa. These glands lubricate the esophagus so that food can pass down.

Question 28

What are the 6 cells of the stomach?

Answer 28

``` Surface mucous cells Neck Mucous cells Stem cells Parietal cells Chief cells DNES (enteric doctrine) cells ```

Question 29

Surface mucous cells

Answer 29

- granules contain glycoproteins (mucins) that combine with water on the surface to form a protective and insoluble gel. They produce HCO3- that diffuses into surface mucous gel

Question 30

Neck mucous cells

Answer 30

Produce soluble mucous

Question 31

What hormones regulate acid secretion

Answer 31

Acetylcholine, histamine, and gastrin | - parietal cells have receptors for all three of these.

Question 32

Why does pH go up after eating a large. Meal

Answer 32

In order for Cl to be excreted from parietal cells, it first has to be taken up. It does this through a Cl-/HCO3- swap. This way, we still have a H+ left over from the break down of H20 and CO2 to be sent out into the lumen.

Question 33

What activates chief cells?

Answer 33

Acetylcholine or secretin.

Question 34

What activates Pepsinogen?

Answer 34

H+

Question 35

Stem cells

Answer 35

- in base of gastric pits - give rise to mature epithelium in 4-5 days - replace damaged cells rom the gastric lumen

Question 36

What 5 things act in a protective role of the GI epithelium?

Answer 36

``` Bicarbonate mucus Prostaglandins that increase local circulation and secretion of HCO3- Tight junctions Pepsinogen Stem cells ```

Question 37

6 cells of the SI

Answer 37

``` Enterocytes Goblet cells Paneth cells immune cells Stem cells DNES cells ```

Question 38

Enterocytes

Answer 38

Absorption of lipids in order to make chylomicrons. . - also absorbs sugars, AAs, vitamins, minerals, ions, and water. - makes enzymes associated with glycocalyx

Question 39

What are the names of the two arteriolar systems in the villi? What other part of the circulatory system is in the villi?

Answer 39

Capillary villus plexus - supplies the tip of the villi Pericryptal capillary plexus - supplies the crypt - Also has a lacteal