Histology of the Lower GI Tract (Small and Large Intestine)

Question 1

What can the small intestine secrete

Answer 1

CCK, VIP, secretin

Question 2

Chyme

Answer 2

semifluid mass of partly digested food expelled by the stomach into duodenum

Question 3

Villi of the small intestine

Answer 3

• folds of mucosa projecting into the lumen

- increase absorptive surface area

Question 4

4 degrees of folding in SI

Answer 4

Plicae circularis, Intestinal villi, Intestinal glands (Crypts of Lieberkuhn, and microvilli

Question 5

Where in the SI are the plicae circularis most prevelant

Answer 5

duodenum

Question 6

Where in the SI are the plicae circularis least prevelant

Answer 6

ileum

Question 7

Function of intestinal villi of SI

Answer 7

increase surface area

form crypts of Lieberkuhn

Question 8

How do the plicae and the villi increase the surface area

Answer 8

when the SI gets more full, they flatten out but once they it empties- they go back up

Question 9

Function of crypts of Lieberkuhn

Answer 9

formed by mucosa and increase surface area

Question 10

What are the cells of the crypts

Answer 10

absorptive, goblet, Paneth, enteroendocrine

Question 11

What cell makes up the brush border

Answer 11

microvilli

Question 12

Where is the muscularis mucosa located

Answer 12

between the mucosa and the submucosa

Question 13

What are the two layers of the muscularis mucosa

Answer 13

muscularis externa and serosa

Question 14

What is the muscularis externa

Answer 14

responsible for segmentation and peristalsis

Question 15

What is the serosa

Answer 15

loose CT covered by visceral peritoneum

Question 16

Mesothelioma

Answer 16

aggressive form of cancer that attacks the mesothelium of the pericardial, pleural, or peritoneal cavity

Question 17

Segmentation

Answer 17

pattern of annular contraction of the smooth muscle layers in the walls of SI

Question 18

What mechanism is segmentation controlled by

Answer 18

ANS

Question 19

Where does the main distribution of blood and lymph flow occur?

Answer 19

the intestinal submucosa

Question 20

2 capillary networks of the submucosal plexus

Answer 20

villus capillary plexus and pericryptal capillary plexus

Question 21

What is the function of the 2 capillary networks of the submucosal plexus

Answer 21

sends nerves into the villi

Question 22

Where are lacteals found?

Answer 22

in the core of the villus

Question 23

Function of lacteals

Answer 23

lymphatic mechanism and give rise to small lymphatic vessels and this will flow into the portal vein

Question 24

Where is chyle made

Answer 24

lacteal

Question 25

Function of chyle

Answer 25

lymph containing lipids absorbed from a meal from intestine to lymphatic circulation and to thoracic duct and into systemic blood circulation

Question 26

Innervation for motility

Answer 26

ANS through submucosal and myenteric plexi

Question 27

Innervation for extrinsic input

Answer 27

from CNS thru parasym and sympath nerve trugs

Question 28

Histologic difference for duodenum

Answer 28

Brunner's glands in submucosa, few goblet cells

Question 29

Histologic difference for jejunum

Answer 29

Well-developed plicae circulares | No Brunner's glands and no peyer's patches

Question 30

Histologic differences for ileum

Answer 30

Peyer's patches in laminia propria and submucosa

Question 31

What are peyer's patches

Answer 31

lymphoid nodules

Question 32

Function of absorptive cells/enterocytes

Answer 32

contain intramembranous enzymes (lactase, maltase, sucrase) for carb digestion

Question 33

Explain Lactose intolerance involving enterocytes

Answer 33

if you can't make lactase with enterocytes, can't breakdown and absorb lactose

Question 34

Function of goblet cells

Answer 34

mucus-secreting cells

Question 35

What is the secretory product of goblet cells

Answer 35

glycoproteins

Question 36

What is the function of mucus hydrates

Answer 36

form protective gel to shield from bacteria

Question 37

Function of enteroendocrine cells

Answer 37

secrete peptides

Question 38

Peptides secreted by enteroendocrine cells

Answer 38

gastrin, secretin, CCK

Question 39

Function of gastrin

Answer 39

stimulate gastic motility, HCl, and insulin

Question 40

Function of secretin

Answer 40

stimulate pancreatic bicarbonate secretion and enhance insulin secretion

Question 41

Function of CCK

Answer 41

act on pyloic sphincter to slow emptying, stimulate release of bile and pancreatic enzymes

Question 42

Function of Paneth Cells

Answer 42

secrete antimicrobial proteins to prevent bacterial contact and kill bacteria via enzymatic degradation

Question 43

What are cells that protect the small intestine

Answer 43

goblet cell, tight junctions, peyer's patches, IgA, acidity, peristalsis

Question 44

What happens when the protective system of the small intestine occurs

Answer 44

IBD or Crohn's Disease

Question 45

How does IBD occur?

Answer 45

damage to protective mechanism of SI, infiltration of neutrophils, destruction of intestinal glands, accumulation of lymphocytes

Question 46

What are major complications of IBD

Answer 46

intestinal lumen fibrosis, formation ofo fistulas

Question 47

What is Fecal Microbiota Transplant

Answer 47

fecal matter collected from doner, mixed with saline, and put back into person with problem

Question 48

What is the purpose of fecal microbiota transplant

Answer 48

replace good bacteria that has been killed or suppressed causing bad bacteria to overpopulate the colon

Question 49

Major function of the enterocytes in large intestine

Answer 49

transport of ions and water

Question 50

What type of cells line the large intestine

Answer 50

simple columnar epithelium and lots of goblet cells

Question 51

T/F There is an abundace of plicae circulares and intestinal villi in the large intestine

Answer 51

F, plicae circulares and intestinal villi are not found in the large intestine

Question 52

T/F Crypts of Lieberkuhn are characteristics of the large intestine

Answer 52

True

Question 53

What is the function of goblet cells

Answer 53

lubricate the mucosal surface

Question 54

Function of aldosterone on enterocytes

Answer 54

increase the number of Na+ channels and absorption of Na+

Question 55

What is in the glands of Lieberkuhn in large intestine

Answer 55

goblet cells, enteroendocrine cells, and stem cells

Question 56

What are the taeniae coli

Answer 56

- characteristic feature of the large intestine | - formed by fused bundles of outer smooth muscle layer

Question 57

How are the haustra formed?

Answer 57

by contraction of the taeniae coli and circular smooth muscle layer

Question 58

Main function of appendix

Answer 58

lots of lymphoid tissue, no goblet cells, vault for good bacteria that you can use to reboot the system

Question 59

Epithelium of the rectum

Answer 59

keratinized with two regions - upper and lower

Question 60

What epithelial change occurs at the ano-rectal junction

Answer 60

simple columnar epithelium is replaced by stratified squamous epithelium and inner circular layer thickens to form internal anal sphincter

Question 61

What type of pain is felt if you have dilation above the pectinate line?

Answer 61

visceral pains- not a lot of pain felt

Question 62

What type of pain is felt if you have dilation below the pectinate line?

Answer 62

somatic pain- skeletal muscle which causes pain

Question 63

Importantance of polyps in colorectal tumors

Answer 63

depending on where the polyps and cancer are- determines where the cancer will metastisize (ex. inferior mesenteric if sigmoid colon or L colic flexure.. superior mesenteric if R colic flexure)