Lower GI I Flashcards Preview

Histology Exam III Material > Lower GI I > Flashcards

Flashcards in Lower GI I Deck (47):
1

Layers of the intestinal wall (from inside to outside)

-Mucosa with lamina propria and muscularis mucosa
- Submucosa
- Muscularis layers
-Serosa

2

Histologic Characteristics of Duodenum

-Villi with wide spatulate or "leaflike" distal shape

- Deep crypts of Lieberkuhn

- Brunner's glands with excretory ducts in submucosa

3

Crypts of Lieberkuhn are _______ ______ glands within the _________

simple tubular glands, intestinal mucosa

4

Crypts of lieberkuhn open between adjacent ______ and extend to ________ _______

villi, muscularis mucosa

5

Cell of the crypts of Lieberkuhn

Goblet cells
Enterocytes
Paneth cells
Enteroendocrine cells

6

Enterocytes are _______ epithelial cells

columnar

7

Characteristics of Enterocytes

-Basal nucleus, perinuclear Golgi, apical brush border

- Produce disaccharidases

- Involved in absorption of proteins, carbohydrates, and lipids

- Enzymes present on apical brush border are important in carbohydrate digestion

- Produce enteropeptidase (enterokinase) which is necessary for the activation of pancreatic zymogens and proenzymes

8

Enterocytes produce

Disaccharidases and enteropeptidase (enterokinase)

9

______ is produced by enterocytes and necessary for the activation of pancreatic zymogens and proenzymes

Enteropeptidase (enterokinase)

10

Characteristics of Paneth cells

-Basal crypt cells
- Prominent eosinophilic granules
- Produce lysozyme to control intestinal flora

11

basal crypt cells with prominent eosinophilic granules

Paneth cells

12

Characteristics of Enteroendocrine cells

-Stain with chromium (chromaffin)
- Agyrophilic (respond to silver stains)
- Produce peptide hormones and serotonin
- May produce pancrine or autocrine secretions
- Analogous to unicellular goblet cells
- formed from endodermal stem cells in all regions of the GI tract

13

Enteroendocrin cells of the crypts of Lieberkuhn produce

peptide hormones and serotonin

14

What are enteroendocrine cells mode of secretion

paracrine or autocrine secretions

15

Brunner glands are found in

submucosa of duodenum

16

Brunner's glands are responsible for

- Formation of bicarbonate and mucus

- Supplements bicarbonate from the pancreas

- Necessary to neutralize gastric acid

17

Histological Characteristics of Jejunum

-Villi longer and more narrow than in Duodenum

- Crypts of Lieberkuhn present

- No glands in submucosa

18

Histologic characteristics of Ileum

-Villi are longer and narrower than in jejunum

-Crypts of Lieberkuhn present

- No glands in submucosa

- Peyer's patches

19

Epithelium of large intestine

- Simple columnar epithelium

- Crypts but no villi

20

Functions of large intestine

-Secretion of mucus for lubrication

- Goblet cell is the prominent cell of the large intestine

- Absorption of fluid

- Formation of fecal mass

- Continuation of digestion initiated in small intestine

21

Location of M cells (antigen-presenting cells)

Ileum

22

The epithelial cells of the GI tract are held together by _______ containing the transmembrane proteins ____ and _____, which function to prevent paracellular transport

occluding junctions, claudins and occludins

23

Characteristics of Paneth Cells

-Basophilic basal cytoplasm

- Supranuclear Golgi complex

- Large, intensely acidophilic apical secretory granules

24

Paneth cells secrete (what are the functions of each secretion)

Lysozyme- increase permeability of bacteria by degrading peptidoglycan goat

- Defensins to increase membrane permeability of target organism

- Tumor necrosis factor- alpha (proinflammatory cytokine)
- may phagocytize some microorganims and help regulate intestinal flora

25

What are the three regions of the small intestine

Duodenum
Jejunum
Ileum

26

______ layer coats intestinal epithelial luminal surface

mucosal

27

The mucosal layer of intestines is secreted by

goblet cells

28

The mucosal layer of intestines is made up of how many layer and what are they

It is made up of 2 layers

- Outer layer contains microorganisms
- Inner layer contains:
- Antimicrobial proteins (from Paneth Cells, Enterocytes, and Goblet cells ) that resist microbial penetration

29

Toll-like receptors are found on the surface of

enterocytes

30

What are toll-like receptors

They are found on the surface of enterocytes
fxn:
- Type of pattern recognition receptor
- Recognize structurally conserved molecules broadly shared by pathogens but distinguish from host molecules (pathogen associated molecular patterns (PAMPs))

31

Explain the immune surveillance system with toll-like receptors

- Antigen binds to toll-like receptor on enterocyte surface
----> B cell-activating factor is produced
-------> B cells in lamina propria mature into plasma cells (antibodies)

32

Explain the immune surveillance system with M cells

-Antigen is taken up by M (microfold) cells associated with Peyer patch in the intestinal mucosa
------> Antigens are transported to lymphocytes located in pockets in folds of M cells
-----------> Antigens are bound to Ig receptors on surface of lymphocytes
----------------> Lymphocytes transfer Ig-bound antigen to dendritic cells in lamina propria
-------------------> Dendritic cells interact with T cells in lamina propria to activate immune response

33

The bulk of the body's immune defenses is centered in the

GALT (gut associated lymphatic tissue)

34

Components of GALT

- Transitory aggregations of lymphocytes, neutrophils, eosinophils
- Permanent structures:
- Appendix
- Peyer's patches
- Mesenteric lymph nodes

35

The antigen-presenting cells (APCs) and macrophages of Peyer's patches phagocytize the antigen and present it to ____ and ______ cells as well as _______

helper and cytoxic T cells as well as B lymphocytes

36

what is the function of M cells

Associated with Peyer's patches
- sample particular antigen and present it to antigen-presenting cells in the underlying lamina propria

37

What are Peyer's Patches

- A permanent GALT found in the ileum
- Dome-shaped lymphoid structures
- Contain B- and T-cell dependent area
-Possess high endothelial venules (HEVs), which facilitate entrance of lymphocytes into lymphoid organs form the bloodstream

38

The primary immunoglobulin produced by GALT is ____

IgA (secretory IgA, slgA)

39

IgA is synthesized and secreted by _____ cells in the lamina proper of the gut and picked up at the ____ surface of enterocytes and transported across the cell

plasma, Basal

40

while in the enterocyte, slgA is linked to a protein called ______ that inhibits degradation of the saga by proteolytic enzymes in the GI lumen

Secretory component

41

Secretory IgA, unlike IgG, does not stimulate the _______ but function by

complement system, but functions by coating microorganisms, thus inhibiting microorganisms binding to the epithelium

42

Rapid cell turnover is a ______ mechanism used by the GI epithelium

Protective (particularly true of stomach and small intestine)

43

Lining of most GI tract is replaced every ____ days

5

44

New cells of the small intestine are formed in

the crypts from undifferentiated cells

45

new cells in the esophagus and anus

are formed in the basal layer of stratified epithelium and migrate through sub-basal levels to be sloughed off into the lumen

46

Proliferative compartment of large intestine is found in the

base of the crypts

47

Stem cells are found in what part of the stomach and differentiate into

-stem cells are found in the neck of the gastric glands
- differentiate into
- surface and neck mucus cells (turn over most rapidy)
- Enteroendocrine cells
- Parietal cells
- Chief cells