Histo of SI and LI

Question 1

SI structure and function

Answer 1

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

Question 2

chyme

Answer 2

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

Question 3

plicae circulares

Answer 3

permanent folds of mucosa and submucosa

begin in the duodenum distinct in the jejunum disappear in mid ileum

Question 4

intestinal villi

Answer 4

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

Question 5

intestinal glands

Answer 5

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

Question 6

microvilli

Answer 6

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

Question 7

submucosa and muscaris externa

Answer 7

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

Question 8

segmentation

Answer 8

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

Question 9

peristalsis

Answer 9

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

Question 10

microcirculation of SI

Answer 10

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

Question 11

lacteals

Answer 11

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

Question 12

duodenum

Answer 12

Brunner’s glands
few goblet cells
leaf like villi

Question 13

jejunum

Answer 13

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

Question 14

ileum

Answer 14

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

Question 15

absorptive cells/enterocytes

Answer 15

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

Question 16

goblet cells

Answer 16

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

Question 17

paneth cells

Answer 17

secrete antimicrobial proteins to limit bacteria enterocyte contact
kill bacteria directly

Question 18

protection of SI

Answer 18

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

Question 19

IBD

Answer 19

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

Question 20

mucosa of large intestine

Answer 20

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

Question 21

mucosa of colon

Answer 21

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

Question 22

enterocytes of LI

Answer 22

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

Question 23

glands of Lieberkuhn

Answer 23

contain goblet cells, enteroendocrine cells, and stem cells

NO paneth cells

Question 24

taenia coli

Answer 24

fused bundles of the outer smooth m layer

contraction produce haustra

Question 25

appendix

Answer 25

thickening of wall due to accumulations of lymphoid tissue

Question 26

ano-rectal junction

Answer 26

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

Question 27

ano rectal junction after pectinate line

Answer 27

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