Intestines

Question 1

Portions of small intestine

Answer 1

. Duodenum
. Jejunum
. Ileum

Question 2

Pelican circulares

Answer 2

. Visible naked eye folds 
. Formed by mucosa and submucosa 
. Most abundant in jejunum 
. Disappear in distal ileum 
. Inc. surface area of small intestine

Question 3

Villi

Answer 3

Finger-like projections of epithelium and lamina propria into lumen

Question 4

Crypts of Lieberkuhn

Answer 4

. Btw villi
. Epithelium deepens into lamina propria and forms tubular glands
. Extend to muscularis mucosae

Question 5

Cells of epithelial lining

Answer 5

. Enterocytes 
. Goblet cells 
. Enteroendocrine cells 
. Stem cells 
. Paneth cells 
. M (microfold) cells

Question 6

Enterocytes

Answer 6

. Tall absorptive cells forming simple columnar epithelium
. Covered w/ micovilli forming brush border covered w/ glycocalyx
. Joined by terminal bars
. Absorb nutrients from lumen of small intestine

Question 7

Lacteal

Answer 7

Hold lipids at core of villus in small intestine

Question 8

Goblet cells

Answer 8

. Basally located nucleus
. Apical side w/ secretory granules
. Granules w/ glycoprotein
. Secretes onto luminal surface to lubricate and protect lining
. Joined to enterocytes via tight junctions

Question 9

Enteroendocrine cells

Answer 9

. Scarce on surface 
. Clear cytoplasm w/ round nucleus 
. Basally located granules 
. Secrete into vascular system 
. Gastrin, secretin, CCK, somatostatin, glucagon-like substance, gastric-inhibitory peptide, and motilin

Question 10

Stem cells in small intestine

Answer 10

. Seen in bases of crypts

. Replenish epithelial cells every 4-5 days

Question 11

Paneth cells

Answer 11

. Many in bases of crypts in ileum
. Exocrine cells w/ large eosinophilia granules in apical cytoplasm
. Produce lysozyme and anti-microbial factors

Question 12

M (microfold) cells

Answer 12

. Specialized epithelial cells
. Seen in ileum
. Overlie peyer’s patches
. Form membrane invaginations where intraepithelial lymphocytes and antigen presenting cells are found
. Facilitate presentation of food antigens to immune cells of peyers patches

Question 13

Lamina propria in small intestine

Answer 13

Loose CT w/ blood and lymph vessels and nerve fibers

. Makes core of each villus

Question 14

Muscularis mucosae in small intestine

Answer 14

. Inner circular and outer longitudinal smooth muscle extending into villi facilitating rhythmic movements

Question 15

Submucosa in small intestine

Answer 15

. CT rich in collagen and elastic fibers
. Meissner’s plexus present
. Duodenum: brunner’s glands
. Ileum: peyer’s patches of lymph

Question 16

Muscularis mucosae in small intestine

Answer 16

. Auerbach’s plexus inbetween outer longitudinal and inner circular layers of smooth muscle

Question 17

Outer layer in duodenum

Answer 17

Adventitia

Question 18

Outer layer in jejunum and ileum

Answer 18

Serosa

Question 19

Mesenteric intestine

Answer 19

. Jejunum and ileum because they are invested in mesentery proper

Question 20

Duodenum unique characteristics

Answer 20

. Villi broad and leaf-shaped

. Brunner’s glands

Question 21

Brunner’s glands

Answer 21

Coiled tubular glands that open into intestinal glands

. Produce alkaline mucous secretion protecting intestinal lining and neutralizes stomach acid

Question 22

Jejunum unique characteristics

Answer 22

. finger-shaped villi

. Plicae circulares taller and thicker than ileum

Question 23

Ileum unique characteristics

Answer 23

. Shorter villi than jejunum
.more goblets
. GALT in lamina propria
. Payer’s patches

Question 24

Payer’s patches

Answer 24

. Accumulations of lymphoid tissue that extend from mucosa into submucosa

Question 25

Total absorptive area of small intestine

Answer 25

200 m2

Question 26

Celiac disease

Answer 26

. Autoimmune . Loss of villous architecture, looks similar to colon . Caused by autoimmune damage to epithelial cells from gluten sensitivity . CD8+ T-cells on surface and CD4+ T cells and lamina propria

Question 27

Mucosa of large intestine

Answer 27

. Lacks villi . Has glands of Lieberkuhn into lamina propria containing goblet cells, stem cells, and neuroedocrine (enteroendocrine) cells . Simple columnar epithelium w/ absorptive cells and goblet cells . Lamina propria w/ lymph tissue . Normal muscularis mucosae

Question 28

Submucosa in large intestine

Answer 28

. Dense CT | . No glands

Question 29

Muscularis externa in large intestine

Answer 29

. Outer longitudinal layer discontinuous making taeniae coli . Myenteric plexus lies between 2 muscle layers

Question 30

Parts of large intestine covered by serosa

Answer 30

. Cecum . Transverse . Sigmoid . Partly ascending and descending colon and rectum

Question 31

Parts of large intestine covered partially by adventitia

Answer 31

. Ascending colon . Descending colon . Rectum

Question 32

Appendices epiploica

Answer 32

. Serosa of large intestine containing pendulous lobules PAF fat

Question 33

Appendix

Answer 33

. Basic architecture of large intestine . Tons of lymphoid tissue in mucosa and submucosa . Mucosal glands shorter and less densely packed than large intestine

Question 34

Recto-anal junction

Answer 34

. At lower end of rectum . Rectal columns of Morgagni: mucosa thrown into longitudinal folds . Columns meet inferiorly to form anal valves (pectinate line)

Question 35

Changes seen in recto-anal junction

Answer 35

. Epithelium goes from simple columnar to SSNK . Muscularis mucosa breaks up and no distinction btw lamina propria and submucosa . Combined lamina-propria submucosal layer contains large thin-walled veins . Inn circle of muscularis externa enlarges to form internal anal sphincter

Question 36

Adenocarcinoma

Answer 36

. Develops from benign adenomatous polyps in mucosal epithelium . Polyps occur in epithelium of rectum, sigmoid colon, or distal descending colon . More common in low-fiber diets . Screenings: colonoscopy or sigmoidoscopy . Fecal occult blood from mucosal bleeding when cancer invades deeply into mucosa