Histology of Lower GI Tract - Cole Flashcards Preview

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Flashcards in Histology of Lower GI Tract - Cole Deck (30)
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1

What does peristalsis do?

Mixes food with gastric secretions including HCl, pepsinogen, gastric lipase and intrinsic factor to create chyme

2

Structure and function of the small intestine

Chemical digestion
Neutralize acidic chyme from stomach
Use segmentation to mix
Absorb good shit
Secrete mucus
Secrete CCK, VIP and secretin
Longest part of GI

3

What are the four degrees of folding in the small intestine?

1. Plicae circulares
2. Intestinal villi
3. Intestinal glands (Crypts of Liberkuhn)
4. Microvilli on apical surface of enterocytes (brush border)

4

Where are the plicae circulares distinct?

The jejunum
Disappear in the mid-ileum

5

The villi extend into what area and form what things?

Extend into mucosa to form the crypts
Ends at muscularis mucosae
-length depends on distention

6

What is the muscularis externa responsible for?

Segmentation - mix chyme, ANS
Peristalsis - movement, coordinated with relaxation below

7

What is the boundary between the mucosa and submucosa?

Muscularis mucosa

8

What is the main distribution site of blood and lymphatic flow?

The intestinal submucosa

9

Lacteals job

Convey chyle that is packaged in chylomicrons

10

Defining characteristics of duodenum

Brunner's glands (mucus) in submucosa
Relatively few goblet cells
Leaf-like villi

11

Defining characteristics of jejunum

Plicae circulares
Irregular villi
More goblet cells
NO Brunner's glands and Peyer's patches

12

Defining characteristics of ileum

Many lymphoid nodules (Peyer's patches) in LP and submucosa
Finger-like villi
Most goblet cells

13

What part of small intestine has Peyer's patches?

Ileum
-finger-like villi
-most goblet cells

14

Crypts are lined by 4 types of cells types

Enterocytes - absorptive cells
Goblet cells
Paneth cells
Enteroendocrine cells

15

Defining characteristics of Goblet cells

Columnar mucus-secreting
Secretory product - 80% carbs, 20% protein
Forms a protective gel coat to shield from abrasion and bacteria

16

Gastrin

Stimulates gastric motility, HCl and insulin

17

Secretin

Stimulates pancreatic bicarbonate secretion and enhances insulin secretion

18

CCK

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

19

Paneth cells

Secrete antimicrobial proteins
Kill bacteria directly

20

What protects the small intestine?

Gel blanket from goblet cells
Tight junction barrier
Peyer's patches
IgA - neutralizes antigens
Paneth cells that secrete microbial pathogens
Acidity of the gastric juice kills microorganisms
Propulsive movement prevents colonization

21

Defining characteristics of IBD

Defect in the protective stem - terminal ileum
Initial alteration is neutrophils into the crypts
Inflammatory process infiltrates the submucosa and muscularis
Major complications - occlusion by fibrosis and formation of fistulas
Segments affected are separated by normal stretches

22

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

Transport of ions and water
-have short apical microvilli

23

What is the mucosa of the large intestine lined by?

Simple columnar epithelium formed by enterocytes and abundant goblet cells

24

What is not found past the ileocecal valve in the large intestine?

Plicae circulares and intestinal villi

25

What is the big difference between small and large intestine?

Large has no Paneth cells

26

Defining characteristics of large intestine?

Taeniae coli - fused bundles of the outer smooth muscle layer

27

Haustra

Saccular structures on large intestine domed by contraction of taeniae coli and inner circular smooth muscle layer

28

Appendix

Large accumulations of lymphoid tissue in LP and submucosa
Often fatty tissue in submucosa

29

Innervation of rectum

Above pectinate line - endoderm, like viscera
Below - ectoderm, like skin
*why external hemorrhoids hurt like hell

30

Colorectal tumors

Polyp - common > 60
Can be familial adenomatous polyposis