Lecture 34: Lower GI Histology

Question 1

Duodenum

Answer 1

Villi: spatulate/leaf-like
Deep crypts of Lieberkuhn
Brunner’s glands present

Question 2

Jejunum

Answer 2

Villi: long and narrow
Crypts of Lieberkuhn present
NO submucosal glands

Question 3

Ileum

Answer 3

Villi: long and narrow, rounded at the tip
Crypts of Lieberkuhn present
NO submucosal glands

Question 4

Crypts of Lieberkuhn

Answer 4

Simple tubular glands with intestinal mucosa; open between adjacent villi and extend to muscularis mucosa

Question 5

Goblet cells

Answer 5

Secrete mucus, stem cells

Question 6

Enterocytes

Answer 6

Columnar epithelial cells with basal nuclei, perinuclear Golgi, and apical brush border. Produce dissacharidases, enteropeptidases, and other enzymes which digest different types of food molecules and activate zymogens

Question 7

Paneth cells

Answer 7

Basal crypt cells with eosinophilic granules; secrete lysozyme, defensins, and tumor necrosis factor alpha; may phagocytize some microorganisms to help regulate intestinal flora

Question 8

Enteroendocrine cells

Answer 8

Stain with chromium, silver; produce peptide hormones and serotonin; may produce paracrine or autocrine secretions

Question 9

Brunner’s glands

Answer 9

Form bicarbonate and mucus to neutralize gastric acid; found in the submucosa of the duodenum

Question 10

What are the functions of the large intestine?

Answer 10

Secrete mucous/lubrication, absorption of fluid, formation of fecal mass, continuation of digestion

Question 11

Occluding/tight junctions of GI tract

Answer 11

Protective mechanism that prevents toxic material from seeping back through gut wall and into lamina propria (which would cause infection)

Question 12

Inner mucosal layer secreted by goblet cells

Answer 12

Contains antimicrobial proteins which resist microbial penetration

Question 13

Rapid cell turnover

Answer 13

Protective mechanism that replaces cells lost in GI tract due to hostile environment

Question 14

What are toll-like receptors?

Answer 14

Pattern recognition receptor which recognizes structurally conserved molecules broadly shared by pathogens (PAMPs); located on enterocytes

Question 15

What is IgA’s role in defense of the gut tract?

Answer 15

Primary immunoglobulin released by GALT; IgA directly coats microorganisms, inhibiting them from binding to epithelium

Question 16

Role of M cells in defense of gut tract

Answer 16

Sample particulate antigen and present to antigen presenting cells in underlying lamina propria

Question 17

GALT

Answer 17

Gut Associated Lymphoid Tissue; contains aggregation of lymphocytes, eosinophils, neutrophils; contain appendix, Peyer’s patches, mesenteric lymph nodes

Question 18

Peyer’s patches

Answer 18

Dome shaped lymphoid structures under mucosal surface with B and T-cell dependent areas and many HEVs

Question 19

Which of the following best describes the olfactory mucosa?

A. Stratified columnar epithelium with goblet cells and a distinct basement membrane
B. Simple ciliated columnar epithelium with goblet cells and a distinct basement membrane
C. Stratified, non-keratinized epithelium lacking goblet cells with thick basement membrane
D. Pseudostratified ciliated columnar epithelium lacking goblet cells with no distinct basement membrane

Answer 19

D. Pseudostratified ciliated columnar epithelium lacking goblet cells with no distinct basement membrane

Question 20

Which of the following is NOT a necessary part of the respiratory membrane?

A. pneumocyte I
B. basal lamina of pneumocyte I
C. dust cells
D. basal lamina of endothelial cell
E. endothelial cell

Answer 20

C. dust cells

Question 21

Which of the following is characteristic of an arteriole?

A. Thick tunica adventitia and large lumen
B. Thick tunica media in relation to size of lumen
C. Thin tunica media and relatively large lumen
D. Large blood-filled lumen
E. Large amounts of elastic fibers in tunica media

Answer 21

B. Thick tunica media in relation to size of lumen

Question 22

Where in the body of a normal, healthy individual would you expect most erythrophagocytosis to be occurring?

A. Marginal zone of spleen
B. Medulla of thymus
C. Hematopoietic cord in bone marrow
D. Cords of Billroth in spleen
E. Paratrabecular sinus in lymph node

Answer 22

D. Cords of Billroth in spleen

Question 23

Which of the following sequences best describes the flow of RBCs through the spleen?

A. Trabecular arteries, central arteries, splenic arteries, penicillus, venous sinuses
B. Splenic artery, central arteries, trabecular arteries, venous sinuses, penicilus
C. Trabecular arteries, splenic arteries, central arteries, penicillus, venous sinuses
D. Splenic artery, trabecular arteries, central arteries, penicillus, venous sinuses

Answer 23

D. Splenic artery, trabecular arteries, central arteries, penicillus, venous sinuses

Question 24

The simple cuboidal epithelium of this portion of the kidney tubule is composed of cells in the form of truncated pyramids which are characterized by basal striations that mark the location of the mitochondria

A. Proximal convoluted tubule
B. Descending thin segment of loop of Henle
C. Ascending thick segment of loop of Henle
D. Distal convoluted tubules
E. Collecting ducts

Answer 24

A. Proximal convoluted tubule

Question 25

Renin is secreted by which of the following?

A. Liver
B. Macula densa
C. Atrial cells of heart
D. Mesangial cells
E. Juxtaglomerular cells

Answer 25

E. Juxtaglomerular cells