Exam 4: Review Questions Small Intestine

Question 1

Compare the lengths of the Duodenum, Illeum , and the jejunum

Answer 1

Dudodenum smallest at 25 cm, Jejunum Second smallest at 2.5 m, Illeum longest at 3.5 m.

Question 2

Describe the layers of the small intestines going from outside to the inner luminal layer

Answer 2

1) Tunica Serosa 2) Tunica Muscularis ( Outer longitudinal layer, myenteric plexus, inner circular layer) 3) Tunica Submucosa 4) Lamina Muscularis Mucosa Lamina propria, Lamina epithelialis (Tunica Mucosa)

Question 3

Dudodenum Tunica Mucosa (Lamina Epithelialis) Composition

Answer 3

1) Villi to increase surface area 2) Enterocytes (simple columnar epithelium, which contain microvilli which increase absorption capability, replaced every 4-6 days) 3) Goblet Cells (secretes mucous to protect the lining of the G.I tract) replaced every 4-6 days) 4) Neuroendocrine Cells 5) M Cells

Question 4

Neuroendocrine cells

Answer 4

Secrete gastrin motilin, VIP etc.

Question 5

M Cells

Answer 5

modified epithelial cells who cover peyer’s patches endocytose and transport macromolecules and gram-positive bacteria to intraepithelial lymphocytes and other immune cells.

Question 6

Duodenum Tunica Mucosa (Lamina Propria) Composition

Answer 6

1) Reticular, elastic, and loose collagenous elastic fibers. Also have lacteals, blood vessels (absorb small chain fatty acids) , and smooth muscle 2) Lymph follicles (Peyer’s Patches) 3) Cypts of Lieberkuhn 4) Simple columnar epithelium, goblet cells, neuroendocrine cells, and paneth cells

Question 7

Paneth cells

Answer 7

located at the base of the crypts of Lieberkuhn ; eosinophilic granules, secrete antimicrobial substances such as lysozyme.

Question 8

Dudodenum Tunica mucosa (Lamina Muscularis) Composition

Answer 8

Thin layer of both inner circular and outer longtitudinal smooth muscle

Question 9

Crypts of Lieberkun

Answer 9

Glands located at the base of villi that are exposed to the lumen of the duodenum

Question 10

Duodenum Tunica Submucosal arrangement

Answer 10

1) Make of the core of Plica Circulares 2) DCT in humans LCT in domestic animals 3) Contain Brunner’s Glands, Peyer’s patches, adipose cells, blood vessels and Meissner’s plexus 4) Distinct of the duodenum

Question 11

Brunner’s Glands

Answer 11

1) Tubuloalveolar glands 2) Serous and mucous secreting in humans and cats 3) simple columnar epithelium w/goblet cells interspersed

Question 12

Dudodenum Tunica Muscularis

Answer 12

1) Thicker inner circular smooth muscle layer Thinner longitudinal smooth muscle layer 2) Auebach’s or myenteric plexus (parasympathetic ganglia between muscle layers)

Question 13

Duodenum vs. Jejunum

Answer 13

Similar anatomically and histologically with the exception of the presence of Brunner’s glands in the duodenum.

Question 14

Ileum differences

Answer 14

Larger peyer’s patches

Question 15

Cecum

Answer 15

First section of the large intestine in humans, diverticulum of ascending colon in domestic animals

Question 16

Veriform Appendix

Answer 16

Worm like appendage of cecum in humans. Plays an immune function: large numbers of lymphatic nodules that protrude into the submucosa

Question 17

Cecum morphology

Answer 17

same as the duodenum except w/o veriform appendix and doesn’t have lacteals. has smaller versions of peyer’s patches.

Question 18

Rectum

Answer 18

Similar to the colon, which is similar to the ileum. The rectum has a thicker tunica muscularis.

Question 19

Anal Canal

Answer 19

Similar morphology to the colon 1) Subdivided into colorectal, transitional, and squamous zones in humans 2) 4cm in length 3) The lamina muscularis disappears at the level of anal transitional/intermediate zones 3) Thicker inner circular layer of tunica muscularis forms anal sphincter. 4) Technically has a tunica adventitia

Question 20

To be able to describe and diagram in detail, the route a bolus of food will travel as it moves through the digestive system from the lips to the anus.

Answer 20

1) Rima Oris (entrance to the oral cavity w/ labia as a boundary) 2) Oral Cavity 3) Pharynx 4) Esophagus 5) Stomach (Cardia, Fundus, Body, Pylorus) 6) Small intestine (Duodenum, Jejunum, Ileum) 7) Large intestine (Cecum, Ascending colon, Transverse colon, descending colon, sigmoid colon 8) Rectum 9) Anal canal