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

GI System Midterm > Histology of the Lower GI Tract (Small and Large Intestine) > Flashcards

Flashcards in Histology of the Lower GI Tract (Small and Large Intestine) Deck (63):
1

What can the small intestine secrete

CCK, VIP, secretin

2

Chyme

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

3

Villi of the small intestine

- folds of mucosa projecting into the lumen
- increase absorptive surface area

4

4 degrees of folding in SI

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

5

Where in the SI are the plicae circularis most prevelant

duodenum

6

Where in the SI are the plicae circularis least prevelant

ileum

7

Function of intestinal villi of SI

increase surface area
form crypts of Lieberkuhn

8

How do the plicae and the villi increase the surface area

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

9

Function of crypts of Lieberkuhn

formed by mucosa and increase surface area

10

What are the cells of the crypts

absorptive, goblet, Paneth, enteroendocrine

11

What cell makes up the brush border

microvilli

12

Where is the muscularis mucosa located

between the mucosa and the submucosa

13

What are the two layers of the muscularis mucosa

muscularis externa and serosa

14

What is the muscularis externa

responsible for segmentation and peristalsis

15

What is the serosa

loose CT covered by visceral peritoneum

16

Mesothelioma

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

17

Segmentation

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

18

What mechanism is segmentation controlled by

ANS

19

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

the intestinal submucosa

20

2 capillary networks of the submucosal plexus

villus capillary plexus and pericryptal capillary plexus

21

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

sends nerves into the villi

22

Where are lacteals found?

in the core of the villus

23

Function of lacteals

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

24

Where is chyle made

lacteal

25

Function of chyle

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

26

Innervation for motility

ANS through submucosal and myenteric plexi

27

Innervation for extrinsic input

from CNS thru parasym and sympath nerve trugs

28

Histologic difference for duodenum

Brunner's glands in submucosa, few goblet cells

29

Histologic difference for jejunum

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

30

Histologic differences for ileum

Peyer's patches in laminia propria and submucosa

31

What are peyer's patches

lymphoid nodules

32

Function of absorptive cells/enterocytes

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

33

Explain Lactose intolerance involving enterocytes

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

34

Function of goblet cells

mucus-secreting cells

35

What is the secretory product of goblet cells

glycoproteins

36

What is the function of mucus hydrates

form protective gel to shield from bacteria

37

Function of enteroendocrine cells

secrete peptides

38

Peptides secreted by enteroendocrine cells

gastrin, secretin, CCK

39

Function of gastrin

stimulate gastic motility, HCl, and insulin

40

Function of secretin

stimulate pancreatic bicarbonate secretion and enhance insulin secretion

41

Function of CCK

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

42

Function of Paneth Cells

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

43

What are cells that protect the small intestine

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

44

What happens when the protective system of the small intestine occurs

IBD or Crohn's Disease

45

How does IBD occur?

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

46

What are major complications of IBD

intestinal lumen fibrosis, formation ofo fistulas

47

What is Fecal Microbiota Transplant

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

48

What is the purpose of fecal microbiota transplant

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

49

Major function of the enterocytes in large intestine

transport of ions and water

50

What type of cells line the large intestine

simple columnar epithelium and lots of goblet cells

51

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

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

52

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

True

53

What is the function of goblet cells

lubricate the mucosal surface

54

Function of aldosterone on enterocytes

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

55

What is in the glands of Lieberkuhn in large intestine

goblet cells, enteroendocrine cells, and stem cells

56

What are the taeniae coli

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

57

How are the haustra formed?

by contraction of the taeniae coli and circular smooth muscle layer

58

Main function of appendix

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

59

Epithelium of the rectum

keratinized with two regions - upper and lower

60

What epithelial change occurs at the ano-rectal junction

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

61

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

visceral pains- not a lot of pain felt

62

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

somatic pain- skeletal muscle which causes pain

63

Importantance of polyps in colorectal tumors

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)