Histology of the Small and large intestines

Question 1

What is chyme

Answer 1

semifluid mass from stomach to duodenum

Question 2

What are plicae circulares

Answer 2

they are IN the wall,
includes the mucosa and submucosa
-begin in duodenum and disappear mid ileum

Question 3

What are villi

Answer 3

extensions of mucosa that increase surface area

Question 4

What forms the crypts of Lieberkun?

Answer 4

the villi, they extend deep into the mucosa

Question 5

How can we tell if what we are looking at is a gland or not

Answer 5

if it goes all the way down to the muscularis mucosa, it’s a gland

Question 6

What are crypts of Lieberkuhn?

Answer 6

simple tubular glands that increase intestinal surface area

-formed by ivaginations of mucosa between adjacent intestinal cilli

Question 7

What are microvilli?

Answer 7

evaginations of the apical part of the enterocytes to increase surface area
-produce a brush border on the apical border of ENTEROCYTES

Question 8

What are enterocytes?

Answer 8

epithelial cells lining the lumen

Question 9

What is the border between mucosa and submucosa?

Answer 9

muscularis MUCOSA

Question 10

What is muscularis externa responsible for?

Answer 10

segmentation and peristalsis

Question 11

What is the serosa?

Answer 11

a thin layer of loose CT covered by visceral peritoneum (mesothelium)

Question 12

Which layer is the main distribution site of blood and lymphatic flow?

Answer 12

the submucosa

Question 13

What are the 2 capillary plexuses in the small intestine?

Answer 13

villus and pericryptal capillary networks

Question 14

What does the villus capillary plexus supply?

Answer 14

intestinal villus and upper portion of the crypts of lieberkuhn

Question 15

What does the pericryptal capillary plexus supply?

Answer 15

the lower half of the crypts of lieberkuhn

Question 16

What conveys Chyle (lymph-containing lipids) from the intestine to lymph circulate (thoracic duct)?

Answer 16

lacteals

-within a villus

Question 17

What controls the motility of the small intestine?

Answer 17

the ANS through submucosal and myenteric plexi

Question 18

Where does the intrinsic input come from?

Answer 18

the mucosa and muscle wall of the small intestine

Question 19

Where does the extrinsic input come from?

Answer 19

the CNS through parasympathetic nerve trunks (vagus N.)

Question 20

What cell is specific to the duodenum?

Answer 20

brunner’s glands

-few goblet cells and leaf like villi

Question 21

Where are the brunner’s glands located?

Answer 21

in the submucosa

Question 22

What is a special characteristic of the jejunum?

Answer 22

well developed plicae circulares

• NO brunner’s glands or peyer’s patches
• more goblet cells

Question 23

What is a special characteristic of the Ileum?

Answer 23

peyer’s patches

• LOTS of goblet cells
• finger-like villi

Question 24

What kind of epithelium lines the crypts of lieberkuhn?

Answer 24

simple columnar

Question 25

What are the 4 kinds of cells found int he crypt of lieberkuhn?

Answer 25

1. ) absorptive cells, or ENTEROCYTES
2. ) goblet cells
3. ) paneth cells
4. ) enteroendocrine cells
   * and stem cells I guess

Question 26

What do the enterocytes have in their membranes?

Answer 26

enzymes! to digest carbs

Question 27

What do goblet cells do?

Answer 27

secrete mucus via exocytosis

Question 28

What do enteroendocrine cells do?

Answer 28

secrete peptide hormones controlling several functions of the GI system

Question 29

What are the 3 things that are secreted from enteroendocrine cells?

Answer 29

Gastrin
Secretin
CCK

Question 30

What does gastrin do?

Answer 30

stimulates gastric motility, HCL (parietal cells), and insulin

Question 31

What does secretin do?

Answer 31

Stimulates pancreatic bicarb secretion and enhances insulin release
-opposite of gastrin except for the insulin part

Question 32

What does CCK do?

Answer 32

acts on pyloric sphincter to slow emptying, stimulates release of bile and pancreatic enzymes

Question 33

What do paneth cells do?

Answer 33

secrete antimicrobial proteins to limit bacteria-enterocyte contact
-enzymatic degradation of bacterial wall or disrupt the bacterial inner membrane

Question 34

What is Crohn’s disease

Answer 34

it’s when neutrophils get into the crypts of lieberkuhn and destroy the intestinal glands

Question 35

What is the major function of enterocytes in the large intestine?

Answer 35

transport of Ions and Water

Question 36

Where do we stop seeing plicae circulares or villi?

Answer 36

beyond the ileocecal valve

-BUT there’s lots of straight tubular glands to lubricate

Question 37

What cellular process removes water and concentrated the chyme into semisolid feces?

Answer 37

active transport of sodium

Question 38

What is the main feature of microvilli of the large intestine?

Answer 38

short

Question 39

What does aldosterone do?

Answer 39

increases the absorption of sodium

Question 40

What does the crypts of lieberkuhn have in the large intestine?

Answer 40

goblet cells, eneteroendocrine, and stem cells

NO PANETH CELLS those are in the ileum

Question 41

What smooth muscle layer of the muscularis externa does not aggregate into the taenia coli?

Answer 41

the outer longitudinal smooth muscle layer