Digestive System

Question 1

Describe the Oral Cavity

Answer 1

• lips, cheeks, palate, pharynx, and tongue
• lined by stratified squamous epithelium
• lamina propria of connective tissue
• no submucosa
• dental pad in ruminants with keratinized layer

Question 2

Describe the Tongue

Answer 2

• covered by mucosa of stratified squamous epithelium
• keratinized on dorsal side, and have papillae
• main component is skeletal muscle in three directions
• lamina propria of loose CT and glands
• no submucosa

Question 3

What are the hard structures of the tooth, and what cells produce each?

Answer 3

• enamel covers external surface, produced by ameloblasts
• dentin is beneath enamel, produced by odontoblast
• cementum, produced by cementoblasts

Question 4

What are the soft tissues of the tooth, and what cells produce each?

Answer 4

• tooth pulp is loose CT and nerves in the center of the tooth, derived from neural crest cells
• periodontal ligament holds onto the tooth, produced by fibroblasts

Question 5

What are the possible tunics in generic tubular organs?

Answer 5

• tunica mucosa: epithelium, lamina propria, and muscularis mucosa
• tunica submucosa
• tunica muscularis: inner circular and outer longitudinal
• tunica serosa: lined by mesothelium, adventitia is adhered to another tissue

Question 6

Describe the layers of the esophagus

Answer 6

• mucosa: stratified squamous, loose CT, and muscularis mucosae
• submucosa: mucous glands
• muscularis: two layers of skeletal and/or smooth muscle
• adventitia: loost CT without mesothelium, most of esohpagus
• some is serosa, continuous with peritoneum

Question 7

What type of epithelium lines the forestomachs in the ruminant?

Answer 7

• stratified squamous

- keratinized in reticulum

Question 8

What type of epithelium lines the gastric glands?

Answer 8

simple columnar

Question 9

What are the types of gastric glands?

Answer 9

• cardiac: mucous
• proper gastric: parietal and chief cells
• pyloric: mucous

Question 10

What are the glandular regions and the components of them?

Answer 10

• cardiac: mucous glands and few parietal cells
• fundic: proper gastric glands; parietal and chief cells
• pyloric: mucous glands and G cells

Question 11

What is produced by each of these cells?

Parietal, Chief, and G cells

Answer 11

• parietal: HCl (hydrochloric acid)
• Chief: pepsinogen
• G: gastrin

Question 12

Describe Chief cells

Answer 12

• basophilic, granular cytoplasm
• dense, basally located nucleus
• also called peptic cells
• secrete pepsinogen

Question 13

Describe Parietal cells

Answer 13

• acidophilic
• centrally located nucleus
• large and rounds cells
• secrete HCl and intrinsic factor

Question 14

What type of epithelium lines the intestines?

Answer 14

simple columnar with goblet cells, enteroendocrine cells, and paneth cells

Question 15

What are the features of the small intestine?

Answer 15

• plicae, villi, and microvilli
• villi with crypts of Lieberkahn and lacteals
• submucosal glands in duodenum
• Peyers patches in jejunum and ileum

Question 16

What are the features of the large intestine?

Answer 16

• no villi
• absorbs H2) and secreted mucous
• longer crypts
• pigs and horses have taenia

Question 17

Describe the location and features of Anal Sacs

Answer 17

• paired sacs located lateral and below the anus, between the internal and external sphincters
• lined by keratinized stratified squamous epithelium

Question 18

What type of glands are the Anal Glands?

Answer 18

• apocrine in dogs

- apocrine and sebaceous in cats

Question 19

What type of glands are the Circumanal Glands?

Answer 19

• sebaceous in the upper portion

- non-sebaceous (hepatoid glands) in the lower portion

Question 20

What is the secretory unit of a gland?

Answer 20

adenomere

Question 21

What is the space of Disse?

Answer 21

site of exchange between blood and hepatocyte

Question 22

What is the function of the hepatocyte?

Answer 22

stores lipids and carbohydrates as triglycerides and glycogen

Question 23

Describe a hepatic lobule

Answer 23

• hexagonal shape
• central vein in center
• portal triads at edges
• blood flows towards central vein, bile flows towards portal triads
• Kupffer cells (macrophages) adjacent to sinusoids

Question 24

What is a portal lobule?

Answer 24

• physiological unit of the liver

- triangular area with portal triad in center

Question 25

Describe the zones of the hepatic acinus

Answer 25

Zone 1: perilobular, high O2, nutrients, and pathogen exposure
Zone 2: moderate O2, nutrients, and pathogen exposure
Zone 3: centrilobular (nearest to central vein), low O2, nutrients, and pathogen exposure

Question 26

Describe the Gallbladder

Answer 26

• stores bile from cystic duct
• abundant mucosal folds
• simple columnar epithelium with microvili
• no lamina mucularis mucosae
• serosa surround most of organ

Question 27

Describe the stroma of the pancreas

Answer 27

• thin CT capsule and trabeculae with blood vessels, nerves, and lymph vessels

Question 28

Describe the endocrine aspect of the pancreas

Answer 28

• 5% of parenchyma
• islets of Langerhan
• mostly B cells producing insulin

Question 29

Describe the exocrine aspect of the pancreas

Answer 29

• 95% of parenchyma
• tubuloacinar secretory units
• drain into intercalated ducts lined by cuboidal cells
• interlobular ducts are not striated
• zymogen granules
• serous acinus