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Flashcards in Histo of SI and LI Deck (27):
1

SI structure and function

complete chemical digestion
neutralize acidic chyme
segmentation contractions
absorb majority of nutrients
secrete mucous
secrete CCK, VIP and secretin

2

chyme

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

3

plicae circulares

permanent folds of mucosa and submucosa
begin in the duodenum distinct in the jejunum disappear in mid ileum

4

intestinal villi

finger like projections of the mucosa covering the entire surface of the SI
increase SA

5

intestinal glands

crypts of Lieberkuhn simple tubular glands that increase the intestinal surface area
invaginations of the mucosa b/w adjacent intestinal villi
absorptive, goblet, Paneth and enteroendocrine cells

6

microvilli

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

7

submucosa and muscaris externa

muscularis mucosa - boundary b/w mucosa and submucosa
muscularis externa - responsible for segmentation and peristalis
serosa - thin layer of loose CT covered by visceral peritoneum

8

segmentation

pattern of annular contraction of smooth m layers which mixes the chyme

9

peristalsis

contents advance along intestine when proximal contraction is coordinated with relaxation below

10

microcirculation of SI

intestinal submucosa
villus capillary plexus supplies intestinal villus
pericryptal capillary plexus supplies the lower half of the crypts

11

lacteals

convey chyle from the intestine to the lymphatic circulating and to the thoracic duct and then to the systemic blood circulation

12

duodenum

Brunner's glands
few goblet cells
leaf like villi

13

jejunum

plicae circulares
irregular villi
more goblet cells
no brunner's glands and no peyers patches

14

ileum

many lymphoid nodules (peyer's patches) in LP and submucosa
finger like villi
most goblet cells

15

absorptive cells/enterocytes

apical domain w/ brush border
microvilli contain carbohydrate breakdown enzymes
carrier proteins bring carbohydrates into cell

16

goblet cells

mucus secreting cells throughout enterocytes of intestinal epithelium
secrete glycoproteins
protect against bacterial invasion

17

paneth cells

secrete antimicrobial proteins to limit bacteria enterocyte contact
kill bacteria directly

18

protection of SI

goblet cells - gel like blanket
tight junctions b/w enterocytes
Peyer's patches in epithelium
IgA produced by plasma cells
Paneth cells - inactivation of microbial cells
acidity of gastric juice
propulsion

19

IBD

defect in the protective system accounts for inflammatory bowel diseases
infiltration of neutrophils
inflammation
accumulation of lymphocytes

20

mucosa of large intestine

lined by simple columnar epithelium formed by enterocytes and abundant goblet cells
enterocytes have short apical microvilli - transport of ions and water

21

mucosa of colon

straight tubular glands or crypts are characteristic of the mucosa of the colon

22

enterocytes of LI

simple columnar epithelium
short apical microvilli
effected by aldosterone
goblet cells secrete mucus to lubricate the mucosal surface

23

glands of Lieberkuhn

contain goblet cells, enteroendocrine cells, and stem cells
NO paneth cells

24

taenia coli

fused bundles of the outer smooth m layer
contraction produce haustra

25

appendix

thickening of wall due to accumulations of lymphoid tissue

26

ano-rectal junction

simple columnar epithelium is replaced by stratified squamous epithelium
inner circular layer of smooth m thickens to form the internal anal sphincter

27

ano rectal junction after pectinate line

lined by keratinizing stratifies squamous epithelium
contains sebaceous and sweat glands
external anal sphincter formed by skeletal m